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-rw-r--r--Doc/library/allos.rst2
-rw-r--r--Doc/library/logging.config.rst657
-rw-r--r--Doc/library/logging.handlers.rst814
-rw-r--r--Doc/library/logging.rst4162
4 files changed, 1790 insertions, 3845 deletions
diff --git a/Doc/library/allos.rst b/Doc/library/allos.rst
index b3ef2b1..bf91717 100644
--- a/Doc/library/allos.rst
+++ b/Doc/library/allos.rst
@@ -19,6 +19,8 @@ but they are available on most other systems as well. Here's an overview:
optparse.rst
getopt.rst
logging.rst
+ logging.config.rst
+ logging.handlers.rst
getpass.rst
curses.rst
curses.ascii.rst
diff --git a/Doc/library/logging.config.rst b/Doc/library/logging.config.rst
new file mode 100644
index 0000000..399d4dc
--- /dev/null
+++ b/Doc/library/logging.config.rst
@@ -0,0 +1,657 @@
+:mod:`logging.config` --- Logging configuration
+===============================================
+
+.. module:: logging.config
+ :synopsis: Configuration of the logging module.
+
+
+.. moduleauthor:: Vinay Sajip <vinay_sajip@red-dove.com>
+.. sectionauthor:: Vinay Sajip <vinay_sajip@red-dove.com>
+
+
+.. _logging-config-api:
+
+Configuration functions
+^^^^^^^^^^^^^^^^^^^^^^^
+
+The following functions configure the logging module. They are located in the
+:mod:`logging.config` module. Their use is optional --- you can configure the
+logging module using these functions or by making calls to the main API (defined
+in :mod:`logging` itself) and defining handlers which are declared either in
+:mod:`logging` or :mod:`logging.handlers`.
+
+.. function:: dictConfig(config)
+
+ Takes the logging configuration from a dictionary. The contents of
+ this dictionary are described in :ref:`logging-config-dictschema`
+ below.
+
+ If an error is encountered during configuration, this function will
+ raise a :exc:`ValueError`, :exc:`TypeError`, :exc:`AttributeError`
+ or :exc:`ImportError` with a suitably descriptive message. The
+ following is a (possibly incomplete) list of conditions which will
+ raise an error:
+
+ * A ``level`` which is not a string or which is a string not
+ corresponding to an actual logging level.
+ * A ``propagate`` value which is not a boolean.
+ * An id which does not have a corresponding destination.
+ * A non-existent handler id found during an incremental call.
+ * An invalid logger name.
+ * Inability to resolve to an internal or external object.
+
+ Parsing is performed by the :class:`DictConfigurator` class, whose
+ constructor is passed the dictionary used for configuration, and
+ has a :meth:`configure` method. The :mod:`logging.config` module
+ has a callable attribute :attr:`dictConfigClass`
+ which is initially set to :class:`DictConfigurator`.
+ You can replace the value of :attr:`dictConfigClass` with a
+ suitable implementation of your own.
+
+ :func:`dictConfig` calls :attr:`dictConfigClass` passing
+ the specified dictionary, and then calls the :meth:`configure` method on
+ the returned object to put the configuration into effect::
+
+ def dictConfig(config):
+ dictConfigClass(config).configure()
+
+ For example, a subclass of :class:`DictConfigurator` could call
+ ``DictConfigurator.__init__()`` in its own :meth:`__init__()`, then
+ set up custom prefixes which would be usable in the subsequent
+ :meth:`configure` call. :attr:`dictConfigClass` would be bound to
+ this new subclass, and then :func:`dictConfig` could be called exactly as
+ in the default, uncustomized state.
+
+.. function:: fileConfig(fname[, defaults])
+
+ Reads the logging configuration from a :mod:`configparser`\-format file named
+ *fname*. This function can be called several times from an application,
+ allowing an end user to select from various pre-canned
+ configurations (if the developer provides a mechanism to present the choices
+ and load the chosen configuration). Defaults to be passed to the ConfigParser
+ can be specified in the *defaults* argument.
+
+
+.. function:: listen(port=DEFAULT_LOGGING_CONFIG_PORT)
+
+ Starts up a socket server on the specified port, and listens for new
+ configurations. If no port is specified, the module's default
+ :const:`DEFAULT_LOGGING_CONFIG_PORT` is used. Logging configurations will be
+ sent as a file suitable for processing by :func:`fileConfig`. Returns a
+ :class:`Thread` instance on which you can call :meth:`start` to start the
+ server, and which you can :meth:`join` when appropriate. To stop the server,
+ call :func:`stopListening`.
+
+ To send a configuration to the socket, read in the configuration file and
+ send it to the socket as a string of bytes preceded by a four-byte length
+ string packed in binary using ``struct.pack('>L', n)``.
+
+
+.. function:: stopListening()
+
+ Stops the listening server which was created with a call to :func:`listen`.
+ This is typically called before calling :meth:`join` on the return value from
+ :func:`listen`.
+
+
+.. _logging-config-dictschema:
+
+Configuration dictionary schema
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Describing a logging configuration requires listing the various
+objects to create and the connections between them; for example, you
+may create a handler named 'console' and then say that the logger
+named 'startup' will send its messages to the 'console' handler.
+These objects aren't limited to those provided by the :mod:`logging`
+module because you might write your own formatter or handler class.
+The parameters to these classes may also need to include external
+objects such as ``sys.stderr``. The syntax for describing these
+objects and connections is defined in :ref:`logging-config-dict-connections`
+below.
+
+Dictionary Schema Details
+"""""""""""""""""""""""""
+
+The dictionary passed to :func:`dictConfig` must contain the following
+keys:
+
+* *version* - to be set to an integer value representing the schema
+ version. The only valid value at present is 1, but having this key
+ allows the schema to evolve while still preserving backwards
+ compatibility.
+
+All other keys are optional, but if present they will be interpreted
+as described below. In all cases below where a 'configuring dict' is
+mentioned, it will be checked for the special ``'()'`` key to see if a
+custom instantiation is required. If so, the mechanism described in
+:ref:`logging-config-dict-userdef` below is used to create an instance;
+otherwise, the context is used to determine what to instantiate.
+
+* *formatters* - the corresponding value will be a dict in which each
+ key is a formatter id and each value is a dict describing how to
+ configure the corresponding Formatter instance.
+
+ The configuring dict is searched for keys ``format`` and ``datefmt``
+ (with defaults of ``None``) and these are used to construct a
+ :class:`logging.Formatter` instance.
+
+* *filters* - the corresponding value will be a dict in which each key
+ is a filter id and each value is a dict describing how to configure
+ the corresponding Filter instance.
+
+ The configuring dict is searched for the key ``name`` (defaulting to the
+ empty string) and this is used to construct a :class:`logging.Filter`
+ instance.
+
+* *handlers* - the corresponding value will be a dict in which each
+ key is a handler id and each value is a dict describing how to
+ configure the corresponding Handler instance.
+
+ The configuring dict is searched for the following keys:
+
+ * ``class`` (mandatory). This is the fully qualified name of the
+ handler class.
+
+ * ``level`` (optional). The level of the handler.
+
+ * ``formatter`` (optional). The id of the formatter for this
+ handler.
+
+ * ``filters`` (optional). A list of ids of the filters for this
+ handler.
+
+ All *other* keys are passed through as keyword arguments to the
+ handler's constructor. For example, given the snippet::
+
+ handlers:
+ console:
+ class : logging.StreamHandler
+ formatter: brief
+ level : INFO
+ filters: [allow_foo]
+ stream : ext://sys.stdout
+ file:
+ class : logging.handlers.RotatingFileHandler
+ formatter: precise
+ filename: logconfig.log
+ maxBytes: 1024
+ backupCount: 3
+
+ the handler with id ``console`` is instantiated as a
+ :class:`logging.StreamHandler`, using ``sys.stdout`` as the underlying
+ stream. The handler with id ``file`` is instantiated as a
+ :class:`logging.handlers.RotatingFileHandler` with the keyword arguments
+ ``filename='logconfig.log', maxBytes=1024, backupCount=3``.
+
+* *loggers* - the corresponding value will be a dict in which each key
+ is a logger name and each value is a dict describing how to
+ configure the corresponding Logger instance.
+
+ The configuring dict is searched for the following keys:
+
+ * ``level`` (optional). The level of the logger.
+
+ * ``propagate`` (optional). The propagation setting of the logger.
+
+ * ``filters`` (optional). A list of ids of the filters for this
+ logger.
+
+ * ``handlers`` (optional). A list of ids of the handlers for this
+ logger.
+
+ The specified loggers will be configured according to the level,
+ propagation, filters and handlers specified.
+
+* *root* - this will be the configuration for the root logger.
+ Processing of the configuration will be as for any logger, except
+ that the ``propagate`` setting will not be applicable.
+
+* *incremental* - whether the configuration is to be interpreted as
+ incremental to the existing configuration. This value defaults to
+ ``False``, which means that the specified configuration replaces the
+ existing configuration with the same semantics as used by the
+ existing :func:`fileConfig` API.
+
+ If the specified value is ``True``, the configuration is processed
+ as described in the section on :ref:`logging-config-dict-incremental`.
+
+* *disable_existing_loggers* - whether any existing loggers are to be
+ disabled. This setting mirrors the parameter of the same name in
+ :func:`fileConfig`. If absent, this parameter defaults to ``True``.
+ This value is ignored if *incremental* is ``True``.
+
+.. _logging-config-dict-incremental:
+
+Incremental Configuration
+"""""""""""""""""""""""""
+
+It is difficult to provide complete flexibility for incremental
+configuration. For example, because objects such as filters
+and formatters are anonymous, once a configuration is set up, it is
+not possible to refer to such anonymous objects when augmenting a
+configuration.
+
+Furthermore, there is not a compelling case for arbitrarily altering
+the object graph of loggers, handlers, filters, formatters at
+run-time, once a configuration is set up; the verbosity of loggers and
+handlers can be controlled just by setting levels (and, in the case of
+loggers, propagation flags). Changing the object graph arbitrarily in
+a safe way is problematic in a multi-threaded environment; while not
+impossible, the benefits are not worth the complexity it adds to the
+implementation.
+
+Thus, when the ``incremental`` key of a configuration dict is present
+and is ``True``, the system will completely ignore any ``formatters`` and
+``filters`` entries, and process only the ``level``
+settings in the ``handlers`` entries, and the ``level`` and
+``propagate`` settings in the ``loggers`` and ``root`` entries.
+
+Using a value in the configuration dict lets configurations to be sent
+over the wire as pickled dicts to a socket listener. Thus, the logging
+verbosity of a long-running application can be altered over time with
+no need to stop and restart the application.
+
+.. _logging-config-dict-connections:
+
+Object connections
+""""""""""""""""""
+
+The schema describes a set of logging objects - loggers,
+handlers, formatters, filters - which are connected to each other in
+an object graph. Thus, the schema needs to represent connections
+between the objects. For example, say that, once configured, a
+particular logger has attached to it a particular handler. For the
+purposes of this discussion, we can say that the logger represents the
+source, and the handler the destination, of a connection between the
+two. Of course in the configured objects this is represented by the
+logger holding a reference to the handler. In the configuration dict,
+this is done by giving each destination object an id which identifies
+it unambiguously, and then using the id in the source object's
+configuration to indicate that a connection exists between the source
+and the destination object with that id.
+
+So, for example, consider the following YAML snippet::
+
+ formatters:
+ brief:
+ # configuration for formatter with id 'brief' goes here
+ precise:
+ # configuration for formatter with id 'precise' goes here
+ handlers:
+ h1: #This is an id
+ # configuration of handler with id 'h1' goes here
+ formatter: brief
+ h2: #This is another id
+ # configuration of handler with id 'h2' goes here
+ formatter: precise
+ loggers:
+ foo.bar.baz:
+ # other configuration for logger 'foo.bar.baz'
+ handlers: [h1, h2]
+
+(Note: YAML used here because it's a little more readable than the
+equivalent Python source form for the dictionary.)
+
+The ids for loggers are the logger names which would be used
+programmatically to obtain a reference to those loggers, e.g.
+``foo.bar.baz``. The ids for Formatters and Filters can be any string
+value (such as ``brief``, ``precise`` above) and they are transient,
+in that they are only meaningful for processing the configuration
+dictionary and used to determine connections between objects, and are
+not persisted anywhere when the configuration call is complete.
+
+The above snippet indicates that logger named ``foo.bar.baz`` should
+have two handlers attached to it, which are described by the handler
+ids ``h1`` and ``h2``. The formatter for ``h1`` is that described by id
+``brief``, and the formatter for ``h2`` is that described by id
+``precise``.
+
+
+.. _logging-config-dict-userdef:
+
+User-defined objects
+""""""""""""""""""""
+
+The schema supports user-defined objects for handlers, filters and
+formatters. (Loggers do not need to have different types for
+different instances, so there is no support in this configuration
+schema for user-defined logger classes.)
+
+Objects to be configured are described by dictionaries
+which detail their configuration. In some places, the logging system
+will be able to infer from the context how an object is to be
+instantiated, but when a user-defined object is to be instantiated,
+the system will not know how to do this. In order to provide complete
+flexibility for user-defined object instantiation, the user needs
+to provide a 'factory' - a callable which is called with a
+configuration dictionary and which returns the instantiated object.
+This is signalled by an absolute import path to the factory being
+made available under the special key ``'()'``. Here's a concrete
+example::
+
+ formatters:
+ brief:
+ format: '%(message)s'
+ default:
+ format: '%(asctime)s %(levelname)-8s %(name)-15s %(message)s'
+ datefmt: '%Y-%m-%d %H:%M:%S'
+ custom:
+ (): my.package.customFormatterFactory
+ bar: baz
+ spam: 99.9
+ answer: 42
+
+The above YAML snippet defines three formatters. The first, with id
+``brief``, is a standard :class:`logging.Formatter` instance with the
+specified format string. The second, with id ``default``, has a
+longer format and also defines the time format explicitly, and will
+result in a :class:`logging.Formatter` initialized with those two format
+strings. Shown in Python source form, the ``brief`` and ``default``
+formatters have configuration sub-dictionaries::
+
+ {
+ 'format' : '%(message)s'
+ }
+
+and::
+
+ {
+ 'format' : '%(asctime)s %(levelname)-8s %(name)-15s %(message)s',
+ 'datefmt' : '%Y-%m-%d %H:%M:%S'
+ }
+
+respectively, and as these dictionaries do not contain the special key
+``'()'``, the instantiation is inferred from the context: as a result,
+standard :class:`logging.Formatter` instances are created. The
+configuration sub-dictionary for the third formatter, with id
+``custom``, is::
+
+ {
+ '()' : 'my.package.customFormatterFactory',
+ 'bar' : 'baz',
+ 'spam' : 99.9,
+ 'answer' : 42
+ }
+
+and this contains the special key ``'()'``, which means that
+user-defined instantiation is wanted. In this case, the specified
+factory callable will be used. If it is an actual callable it will be
+used directly - otherwise, if you specify a string (as in the example)
+the actual callable will be located using normal import mechanisms.
+The callable will be called with the **remaining** items in the
+configuration sub-dictionary as keyword arguments. In the above
+example, the formatter with id ``custom`` will be assumed to be
+returned by the call::
+
+ my.package.customFormatterFactory(bar='baz', spam=99.9, answer=42)
+
+The key ``'()'`` has been used as the special key because it is not a
+valid keyword parameter name, and so will not clash with the names of
+the keyword arguments used in the call. The ``'()'`` also serves as a
+mnemonic that the corresponding value is a callable.
+
+
+.. _logging-config-dict-externalobj:
+
+Access to external objects
+""""""""""""""""""""""""""
+
+There are times where a configuration needs to refer to objects
+external to the configuration, for example ``sys.stderr``. If the
+configuration dict is constructed using Python code, this is
+straightforward, but a problem arises when the configuration is
+provided via a text file (e.g. JSON, YAML). In a text file, there is
+no standard way to distinguish ``sys.stderr`` from the literal string
+``'sys.stderr'``. To facilitate this distinction, the configuration
+system looks for certain special prefixes in string values and
+treat them specially. For example, if the literal string
+``'ext://sys.stderr'`` is provided as a value in the configuration,
+then the ``ext://`` will be stripped off and the remainder of the
+value processed using normal import mechanisms.
+
+The handling of such prefixes is done in a way analogous to protocol
+handling: there is a generic mechanism to look for prefixes which
+match the regular expression ``^(?P<prefix>[a-z]+)://(?P<suffix>.*)$``
+whereby, if the ``prefix`` is recognised, the ``suffix`` is processed
+in a prefix-dependent manner and the result of the processing replaces
+the string value. If the prefix is not recognised, then the string
+value will be left as-is.
+
+
+.. _logging-config-dict-internalobj:
+
+Access to internal objects
+""""""""""""""""""""""""""
+
+As well as external objects, there is sometimes also a need to refer
+to objects in the configuration. This will be done implicitly by the
+configuration system for things that it knows about. For example, the
+string value ``'DEBUG'`` for a ``level`` in a logger or handler will
+automatically be converted to the value ``logging.DEBUG``, and the
+``handlers``, ``filters`` and ``formatter`` entries will take an
+object id and resolve to the appropriate destination object.
+
+However, a more generic mechanism is needed for user-defined
+objects which are not known to the :mod:`logging` module. For
+example, consider :class:`logging.handlers.MemoryHandler`, which takes
+a ``target`` argument which is another handler to delegate to. Since
+the system already knows about this class, then in the configuration,
+the given ``target`` just needs to be the object id of the relevant
+target handler, and the system will resolve to the handler from the
+id. If, however, a user defines a ``my.package.MyHandler`` which has
+an ``alternate`` handler, the configuration system would not know that
+the ``alternate`` referred to a handler. To cater for this, a generic
+resolution system allows the user to specify::
+
+ handlers:
+ file:
+ # configuration of file handler goes here
+
+ custom:
+ (): my.package.MyHandler
+ alternate: cfg://handlers.file
+
+The literal string ``'cfg://handlers.file'`` will be resolved in an
+analogous way to strings with the ``ext://`` prefix, but looking
+in the configuration itself rather than the import namespace. The
+mechanism allows access by dot or by index, in a similar way to
+that provided by ``str.format``. Thus, given the following snippet::
+
+ handlers:
+ email:
+ class: logging.handlers.SMTPHandler
+ mailhost: localhost
+ fromaddr: my_app@domain.tld
+ toaddrs:
+ - support_team@domain.tld
+ - dev_team@domain.tld
+ subject: Houston, we have a problem.
+
+in the configuration, the string ``'cfg://handlers'`` would resolve to
+the dict with key ``handlers``, the string ``'cfg://handlers.email``
+would resolve to the dict with key ``email`` in the ``handlers`` dict,
+and so on. The string ``'cfg://handlers.email.toaddrs[1]`` would
+resolve to ``'dev_team.domain.tld'`` and the string
+``'cfg://handlers.email.toaddrs[0]'`` would resolve to the value
+``'support_team@domain.tld'``. The ``subject`` value could be accessed
+using either ``'cfg://handlers.email.subject'`` or, equivalently,
+``'cfg://handlers.email[subject]'``. The latter form only needs to be
+used if the key contains spaces or non-alphanumeric characters. If an
+index value consists only of decimal digits, access will be attempted
+using the corresponding integer value, falling back to the string
+value if needed.
+
+Given a string ``cfg://handlers.myhandler.mykey.123``, this will
+resolve to ``config_dict['handlers']['myhandler']['mykey']['123']``.
+If the string is specified as ``cfg://handlers.myhandler.mykey[123]``,
+the system will attempt to retrieve the value from
+``config_dict['handlers']['myhandler']['mykey'][123]``, and fall back
+to ``config_dict['handlers']['myhandler']['mykey']['123']`` if that
+fails.
+
+.. _logging-config-fileformat:
+
+Configuration file format
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The configuration file format understood by :func:`fileConfig` is based on
+:mod:`configparser` functionality. The file must contain sections called
+``[loggers]``, ``[handlers]`` and ``[formatters]`` which identify by name the
+entities of each type which are defined in the file. For each such entity, there
+is a separate section which identifies how that entity is configured. Thus, for
+a logger named ``log01`` in the ``[loggers]`` section, the relevant
+configuration details are held in a section ``[logger_log01]``. Similarly, a
+handler called ``hand01`` in the ``[handlers]`` section will have its
+configuration held in a section called ``[handler_hand01]``, while a formatter
+called ``form01`` in the ``[formatters]`` section will have its configuration
+specified in a section called ``[formatter_form01]``. The root logger
+configuration must be specified in a section called ``[logger_root]``.
+
+Examples of these sections in the file are given below. ::
+
+ [loggers]
+ keys=root,log02,log03,log04,log05,log06,log07
+
+ [handlers]
+ keys=hand01,hand02,hand03,hand04,hand05,hand06,hand07,hand08,hand09
+
+ [formatters]
+ keys=form01,form02,form03,form04,form05,form06,form07,form08,form09
+
+The root logger must specify a level and a list of handlers. An example of a
+root logger section is given below. ::
+
+ [logger_root]
+ level=NOTSET
+ handlers=hand01
+
+The ``level`` entry can be one of ``DEBUG, INFO, WARNING, ERROR, CRITICAL`` or
+``NOTSET``. For the root logger only, ``NOTSET`` means that all messages will be
+logged. Level values are :func:`eval`\ uated in the context of the ``logging``
+package's namespace.
+
+The ``handlers`` entry is a comma-separated list of handler names, which must
+appear in the ``[handlers]`` section. These names must appear in the
+``[handlers]`` section and have corresponding sections in the configuration
+file.
+
+For loggers other than the root logger, some additional information is required.
+This is illustrated by the following example. ::
+
+ [logger_parser]
+ level=DEBUG
+ handlers=hand01
+ propagate=1
+ qualname=compiler.parser
+
+The ``level`` and ``handlers`` entries are interpreted as for the root logger,
+except that if a non-root logger's level is specified as ``NOTSET``, the system
+consults loggers higher up the hierarchy to determine the effective level of the
+logger. The ``propagate`` entry is set to 1 to indicate that messages must
+propagate to handlers higher up the logger hierarchy from this logger, or 0 to
+indicate that messages are **not** propagated to handlers up the hierarchy. The
+``qualname`` entry is the hierarchical channel name of the logger, that is to
+say the name used by the application to get the logger.
+
+Sections which specify handler configuration are exemplified by the following.
+::
+
+ [handler_hand01]
+ class=StreamHandler
+ level=NOTSET
+ formatter=form01
+ args=(sys.stdout,)
+
+The ``class`` entry indicates the handler's class (as determined by :func:`eval`
+in the ``logging`` package's namespace). The ``level`` is interpreted as for
+loggers, and ``NOTSET`` is taken to mean 'log everything'.
+
+The ``formatter`` entry indicates the key name of the formatter for this
+handler. If blank, a default formatter (``logging._defaultFormatter``) is used.
+If a name is specified, it must appear in the ``[formatters]`` section and have
+a corresponding section in the configuration file.
+
+The ``args`` entry, when :func:`eval`\ uated in the context of the ``logging``
+package's namespace, is the list of arguments to the constructor for the handler
+class. Refer to the constructors for the relevant handlers, or to the examples
+below, to see how typical entries are constructed. ::
+
+ [handler_hand02]
+ class=FileHandler
+ level=DEBUG
+ formatter=form02
+ args=('python.log', 'w')
+
+ [handler_hand03]
+ class=handlers.SocketHandler
+ level=INFO
+ formatter=form03
+ args=('localhost', handlers.DEFAULT_TCP_LOGGING_PORT)
+
+ [handler_hand04]
+ class=handlers.DatagramHandler
+ level=WARN
+ formatter=form04
+ args=('localhost', handlers.DEFAULT_UDP_LOGGING_PORT)
+
+ [handler_hand05]
+ class=handlers.SysLogHandler
+ level=ERROR
+ formatter=form05
+ args=(('localhost', handlers.SYSLOG_UDP_PORT), handlers.SysLogHandler.LOG_USER)
+
+ [handler_hand06]
+ class=handlers.NTEventLogHandler
+ level=CRITICAL
+ formatter=form06
+ args=('Python Application', '', 'Application')
+
+ [handler_hand07]
+ class=handlers.SMTPHandler
+ level=WARN
+ formatter=form07
+ args=('localhost', 'from@abc', ['user1@abc', 'user2@xyz'], 'Logger Subject')
+
+ [handler_hand08]
+ class=handlers.MemoryHandler
+ level=NOTSET
+ formatter=form08
+ target=
+ args=(10, ERROR)
+
+ [handler_hand09]
+ class=handlers.HTTPHandler
+ level=NOTSET
+ formatter=form09
+ args=('localhost:9022', '/log', 'GET')
+
+Sections which specify formatter configuration are typified by the following. ::
+
+ [formatter_form01]
+ format=F1 %(asctime)s %(levelname)s %(message)s
+ datefmt=
+ class=logging.Formatter
+
+The ``format`` entry is the overall format string, and the ``datefmt`` entry is
+the :func:`strftime`\ -compatible date/time format string. If empty, the
+package substitutes ISO8601 format date/times, which is almost equivalent to
+specifying the date format string ``'%Y-%m-%d %H:%M:%S'``. The ISO8601 format
+also specifies milliseconds, which are appended to the result of using the above
+format string, with a comma separator. An example time in ISO8601 format is
+``2003-01-23 00:29:50,411``.
+
+The ``class`` entry is optional. It indicates the name of the formatter's class
+(as a dotted module and class name.) This option is useful for instantiating a
+:class:`Formatter` subclass. Subclasses of :class:`Formatter` can present
+exception tracebacks in an expanded or condensed format.
+
+.. seealso::
+
+ Module :mod:`logging`
+ API reference for the logging module.
+
+ Module :mod:`logging.handlers`
+ Useful handlers included with the logging module.
+
+
diff --git a/Doc/library/logging.handlers.rst b/Doc/library/logging.handlers.rst
new file mode 100644
index 0000000..a2e1be8
--- /dev/null
+++ b/Doc/library/logging.handlers.rst
@@ -0,0 +1,814 @@
+:mod:`logging.handlers` --- Logging handlers
+============================================
+
+.. module:: logging.handlers
+ :synopsis: Handlers for the logging module.
+
+
+.. moduleauthor:: Vinay Sajip <vinay_sajip@red-dove.com>
+.. sectionauthor:: Vinay Sajip <vinay_sajip@red-dove.com>
+
+The following useful handlers are provided in the package.
+
+.. currentmodule:: logging
+
+.. _stream-handler:
+
+StreamHandler
+^^^^^^^^^^^^^
+
+The :class:`StreamHandler` class, located in the core :mod:`logging` package,
+sends logging output to streams such as *sys.stdout*, *sys.stderr* or any
+file-like object (or, more precisely, any object which supports :meth:`write`
+and :meth:`flush` methods).
+
+
+.. class:: StreamHandler(stream=None)
+
+ Returns a new instance of the :class:`StreamHandler` class. If *stream* is
+ specified, the instance will use it for logging output; otherwise, *sys.stderr*
+ will be used.
+
+
+ .. method:: emit(record)
+
+ If a formatter is specified, it is used to format the record. The record
+ is then written to the stream with a trailing newline. If exception
+ information is present, it is formatted using
+ :func:`traceback.print_exception` and appended to the stream.
+
+
+ .. method:: flush()
+
+ Flushes the stream by calling its :meth:`flush` method. Note that the
+ :meth:`close` method is inherited from :class:`Handler` and so does
+ no output, so an explicit :meth:`flush` call may be needed at times.
+
+.. versionchanged:: 3.2
+ The ``StreamHandler`` class now has a ``terminator`` attribute, default
+ value ``'\n'``, which is used as the terminator when writing a formatted
+ record to a stream. If you don't want this newline termination, you can
+ set the handler instance's ``terminator`` attribute to the empty string.
+
+.. _file-handler:
+
+FileHandler
+^^^^^^^^^^^
+
+The :class:`FileHandler` class, located in the core :mod:`logging` package,
+sends logging output to a disk file. It inherits the output functionality from
+:class:`StreamHandler`.
+
+
+.. class:: FileHandler(filename, mode='a', encoding=None, delay=False)
+
+ Returns a new instance of the :class:`FileHandler` class. The specified file is
+ opened and used as the stream for logging. If *mode* is not specified,
+ :const:`'a'` is used. If *encoding* is not *None*, it is used to open the file
+ with that encoding. If *delay* is true, then file opening is deferred until the
+ first call to :meth:`emit`. By default, the file grows indefinitely.
+
+
+ .. method:: close()
+
+ Closes the file.
+
+
+ .. method:: emit(record)
+
+ Outputs the record to the file.
+
+
+.. _null-handler:
+
+NullHandler
+^^^^^^^^^^^
+
+.. versionadded:: 3.1
+
+The :class:`NullHandler` class, located in the core :mod:`logging` package,
+does not do any formatting or output. It is essentially a 'no-op' handler
+for use by library developers.
+
+.. class:: NullHandler()
+
+ Returns a new instance of the :class:`NullHandler` class.
+
+ .. method:: emit(record)
+
+ This method does nothing.
+
+ .. method:: handle(record)
+
+ This method does nothing.
+
+ .. method:: createLock()
+
+ This method returns ``None`` for the lock, since there is no
+ underlying I/O to which access needs to be serialized.
+
+
+See :ref:`library-config` for more information on how to use
+:class:`NullHandler`.
+
+.. _watched-file-handler:
+
+WatchedFileHandler
+^^^^^^^^^^^^^^^^^^
+
+.. currentmodule:: logging.handlers
+
+The :class:`WatchedFileHandler` class, located in the :mod:`logging.handlers`
+module, is a :class:`FileHandler` which watches the file it is logging to. If
+the file changes, it is closed and reopened using the file name.
+
+A file change can happen because of usage of programs such as *newsyslog* and
+*logrotate* which perform log file rotation. This handler, intended for use
+under Unix/Linux, watches the file to see if it has changed since the last emit.
+(A file is deemed to have changed if its device or inode have changed.) If the
+file has changed, the old file stream is closed, and the file opened to get a
+new stream.
+
+This handler is not appropriate for use under Windows, because under Windows
+open log files cannot be moved or renamed - logging opens the files with
+exclusive locks - and so there is no need for such a handler. Furthermore,
+*ST_INO* is not supported under Windows; :func:`stat` always returns zero for
+this value.
+
+
+.. class:: WatchedFileHandler(filename[,mode[, encoding[, delay]]])
+
+ Returns a new instance of the :class:`WatchedFileHandler` class. The specified
+ file is opened and used as the stream for logging. If *mode* is not specified,
+ :const:`'a'` is used. If *encoding* is not *None*, it is used to open the file
+ with that encoding. If *delay* is true, then file opening is deferred until the
+ first call to :meth:`emit`. By default, the file grows indefinitely.
+
+
+ .. method:: emit(record)
+
+ Outputs the record to the file, but first checks to see if the file has
+ changed. If it has, the existing stream is flushed and closed and the
+ file opened again, before outputting the record to the file.
+
+.. _rotating-file-handler:
+
+RotatingFileHandler
+^^^^^^^^^^^^^^^^^^^
+
+The :class:`RotatingFileHandler` class, located in the :mod:`logging.handlers`
+module, supports rotation of disk log files.
+
+
+.. class:: RotatingFileHandler(filename, mode='a', maxBytes=0, backupCount=0, encoding=None, delay=0)
+
+ Returns a new instance of the :class:`RotatingFileHandler` class. The specified
+ file is opened and used as the stream for logging. If *mode* is not specified,
+ ``'a'`` is used. If *encoding* is not *None*, it is used to open the file
+ with that encoding. If *delay* is true, then file opening is deferred until the
+ first call to :meth:`emit`. By default, the file grows indefinitely.
+
+ You can use the *maxBytes* and *backupCount* values to allow the file to
+ :dfn:`rollover` at a predetermined size. When the size is about to be exceeded,
+ the file is closed and a new file is silently opened for output. Rollover occurs
+ whenever the current log file is nearly *maxBytes* in length; if *maxBytes* is
+ zero, rollover never occurs. If *backupCount* is non-zero, the system will save
+ old log files by appending the extensions '.1', '.2' etc., to the filename. For
+ example, with a *backupCount* of 5 and a base file name of :file:`app.log`, you
+ would get :file:`app.log`, :file:`app.log.1`, :file:`app.log.2`, up to
+ :file:`app.log.5`. The file being written to is always :file:`app.log`. When
+ this file is filled, it is closed and renamed to :file:`app.log.1`, and if files
+ :file:`app.log.1`, :file:`app.log.2`, etc. exist, then they are renamed to
+ :file:`app.log.2`, :file:`app.log.3` etc. respectively.
+
+
+ .. method:: doRollover()
+
+ Does a rollover, as described above.
+
+
+ .. method:: emit(record)
+
+ Outputs the record to the file, catering for rollover as described
+ previously.
+
+.. _timed-rotating-file-handler:
+
+TimedRotatingFileHandler
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+The :class:`TimedRotatingFileHandler` class, located in the
+:mod:`logging.handlers` module, supports rotation of disk log files at certain
+timed intervals.
+
+
+.. class:: TimedRotatingFileHandler(filename, when='h', interval=1, backupCount=0, encoding=None, delay=False, utc=False)
+
+ Returns a new instance of the :class:`TimedRotatingFileHandler` class. The
+ specified file is opened and used as the stream for logging. On rotating it also
+ sets the filename suffix. Rotating happens based on the product of *when* and
+ *interval*.
+
+ You can use the *when* to specify the type of *interval*. The list of possible
+ values is below. Note that they are not case sensitive.
+
+ +----------------+-----------------------+
+ | Value | Type of interval |
+ +================+=======================+
+ | ``'S'`` | Seconds |
+ +----------------+-----------------------+
+ | ``'M'`` | Minutes |
+ +----------------+-----------------------+
+ | ``'H'`` | Hours |
+ +----------------+-----------------------+
+ | ``'D'`` | Days |
+ +----------------+-----------------------+
+ | ``'W'`` | Week day (0=Monday) |
+ +----------------+-----------------------+
+ | ``'midnight'`` | Roll over at midnight |
+ +----------------+-----------------------+
+
+ The system will save old log files by appending extensions to the filename.
+ The extensions are date-and-time based, using the strftime format
+ ``%Y-%m-%d_%H-%M-%S`` or a leading portion thereof, depending on the
+ rollover interval.
+
+ When computing the next rollover time for the first time (when the handler
+ is created), the last modification time of an existing log file, or else
+ the current time, is used to compute when the next rotation will occur.
+
+ If the *utc* argument is true, times in UTC will be used; otherwise
+ local time is used.
+
+ If *backupCount* is nonzero, at most *backupCount* files
+ will be kept, and if more would be created when rollover occurs, the oldest
+ one is deleted. The deletion logic uses the interval to determine which
+ files to delete, so changing the interval may leave old files lying around.
+
+ If *delay* is true, then file opening is deferred until the first call to
+ :meth:`emit`.
+
+
+ .. method:: doRollover()
+
+ Does a rollover, as described above.
+
+
+ .. method:: emit(record)
+
+ Outputs the record to the file, catering for rollover as described above.
+
+
+.. _socket-handler:
+
+SocketHandler
+^^^^^^^^^^^^^
+
+The :class:`SocketHandler` class, located in the :mod:`logging.handlers` module,
+sends logging output to a network socket. The base class uses a TCP socket.
+
+
+.. class:: SocketHandler(host, port)
+
+ Returns a new instance of the :class:`SocketHandler` class intended to
+ communicate with a remote machine whose address is given by *host* and *port*.
+
+
+ .. method:: close()
+
+ Closes the socket.
+
+
+ .. method:: emit()
+
+ Pickles the record's attribute dictionary and writes it to the socket in
+ binary format. If there is an error with the socket, silently drops the
+ packet. If the connection was previously lost, re-establishes the
+ connection. To unpickle the record at the receiving end into a
+ :class:`LogRecord`, use the :func:`makeLogRecord` function.
+
+
+ .. method:: handleError()
+
+ Handles an error which has occurred during :meth:`emit`. The most likely
+ cause is a lost connection. Closes the socket so that we can retry on the
+ next event.
+
+
+ .. method:: makeSocket()
+
+ This is a factory method which allows subclasses to define the precise
+ type of socket they want. The default implementation creates a TCP socket
+ (:const:`socket.SOCK_STREAM`).
+
+
+ .. method:: makePickle(record)
+
+ Pickles the record's attribute dictionary in binary format with a length
+ prefix, and returns it ready for transmission across the socket.
+
+ Note that pickles aren't completely secure. If you are concerned about
+ security, you may want to override this method to implement a more secure
+ mechanism. For example, you can sign pickles using HMAC and then verify
+ them on the receiving end, or alternatively you can disable unpickling of
+ global objects on the receiving end.
+
+ .. method:: send(packet)
+
+ Send a pickled string *packet* to the socket. This function allows for
+ partial sends which can happen when the network is busy.
+
+
+.. _datagram-handler:
+
+DatagramHandler
+^^^^^^^^^^^^^^^
+
+The :class:`DatagramHandler` class, located in the :mod:`logging.handlers`
+module, inherits from :class:`SocketHandler` to support sending logging messages
+over UDP sockets.
+
+
+.. class:: DatagramHandler(host, port)
+
+ Returns a new instance of the :class:`DatagramHandler` class intended to
+ communicate with a remote machine whose address is given by *host* and *port*.
+
+
+ .. method:: emit()
+
+ Pickles the record's attribute dictionary and writes it to the socket in
+ binary format. If there is an error with the socket, silently drops the
+ packet. To unpickle the record at the receiving end into a
+ :class:`LogRecord`, use the :func:`makeLogRecord` function.
+
+
+ .. method:: makeSocket()
+
+ The factory method of :class:`SocketHandler` is here overridden to create
+ a UDP socket (:const:`socket.SOCK_DGRAM`).
+
+
+ .. method:: send(s)
+
+ Send a pickled string to a socket.
+
+
+.. _syslog-handler:
+
+SysLogHandler
+^^^^^^^^^^^^^
+
+The :class:`SysLogHandler` class, located in the :mod:`logging.handlers` module,
+supports sending logging messages to a remote or local Unix syslog.
+
+
+.. class:: SysLogHandler(address=('localhost', SYSLOG_UDP_PORT), facility=LOG_USER, socktype=socket.SOCK_DGRAM)
+
+ Returns a new instance of the :class:`SysLogHandler` class intended to
+ communicate with a remote Unix machine whose address is given by *address* in
+ the form of a ``(host, port)`` tuple. If *address* is not specified,
+ ``('localhost', 514)`` is used. The address is used to open a socket. An
+ alternative to providing a ``(host, port)`` tuple is providing an address as a
+ string, for example '/dev/log'. In this case, a Unix domain socket is used to
+ send the message to the syslog. If *facility* is not specified,
+ :const:`LOG_USER` is used. The type of socket opened depends on the
+ *socktype* argument, which defaults to :const:`socket.SOCK_DGRAM` and thus
+ opens a UDP socket. To open a TCP socket (for use with the newer syslog
+ daemons such as rsyslog), specify a value of :const:`socket.SOCK_STREAM`.
+
+ Note that if your server is not listening on UDP port 514,
+ :class:`SysLogHandler` may appear not to work. In that case, check what
+ address you should be using for a domain socket - it's system dependent.
+ For example, on Linux it's usually '/dev/log' but on OS/X it's
+ '/var/run/syslog'. You'll need to check your platform and use the
+ appropriate address (you may need to do this check at runtime if your
+ application needs to run on several platforms). On Windows, you pretty
+ much have to use the UDP option.
+
+ .. versionchanged:: 3.2
+ *socktype* was added.
+
+
+ .. method:: close()
+
+ Closes the socket to the remote host.
+
+
+ .. method:: emit(record)
+
+ The record is formatted, and then sent to the syslog server. If exception
+ information is present, it is *not* sent to the server.
+
+
+ .. method:: encodePriority(facility, priority)
+
+ Encodes the facility and priority into an integer. You can pass in strings
+ or integers - if strings are passed, internal mapping dictionaries are
+ used to convert them to integers.
+
+ The symbolic ``LOG_`` values are defined in :class:`SysLogHandler` and
+ mirror the values defined in the ``sys/syslog.h`` header file.
+
+ **Priorities**
+
+ +--------------------------+---------------+
+ | Name (string) | Symbolic value|
+ +==========================+===============+
+ | ``alert`` | LOG_ALERT |
+ +--------------------------+---------------+
+ | ``crit`` or ``critical`` | LOG_CRIT |
+ +--------------------------+---------------+
+ | ``debug`` | LOG_DEBUG |
+ +--------------------------+---------------+
+ | ``emerg`` or ``panic`` | LOG_EMERG |
+ +--------------------------+---------------+
+ | ``err`` or ``error`` | LOG_ERR |
+ +--------------------------+---------------+
+ | ``info`` | LOG_INFO |
+ +--------------------------+---------------+
+ | ``notice`` | LOG_NOTICE |
+ +--------------------------+---------------+
+ | ``warn`` or ``warning`` | LOG_WARNING |
+ +--------------------------+---------------+
+
+ **Facilities**
+
+ +---------------+---------------+
+ | Name (string) | Symbolic value|
+ +===============+===============+
+ | ``auth`` | LOG_AUTH |
+ +---------------+---------------+
+ | ``authpriv`` | LOG_AUTHPRIV |
+ +---------------+---------------+
+ | ``cron`` | LOG_CRON |
+ +---------------+---------------+
+ | ``daemon`` | LOG_DAEMON |
+ +---------------+---------------+
+ | ``ftp`` | LOG_FTP |
+ +---------------+---------------+
+ | ``kern`` | LOG_KERN |
+ +---------------+---------------+
+ | ``lpr`` | LOG_LPR |
+ +---------------+---------------+
+ | ``mail`` | LOG_MAIL |
+ +---------------+---------------+
+ | ``news`` | LOG_NEWS |
+ +---------------+---------------+
+ | ``syslog`` | LOG_SYSLOG |
+ +---------------+---------------+
+ | ``user`` | LOG_USER |
+ +---------------+---------------+
+ | ``uucp`` | LOG_UUCP |
+ +---------------+---------------+
+ | ``local0`` | LOG_LOCAL0 |
+ +---------------+---------------+
+ | ``local1`` | LOG_LOCAL1 |
+ +---------------+---------------+
+ | ``local2`` | LOG_LOCAL2 |
+ +---------------+---------------+
+ | ``local3`` | LOG_LOCAL3 |
+ +---------------+---------------+
+ | ``local4`` | LOG_LOCAL4 |
+ +---------------+---------------+
+ | ``local5`` | LOG_LOCAL5 |
+ +---------------+---------------+
+ | ``local6`` | LOG_LOCAL6 |
+ +---------------+---------------+
+ | ``local7`` | LOG_LOCAL7 |
+ +---------------+---------------+
+
+ .. method:: mapPriority(levelname)
+
+ Maps a logging level name to a syslog priority name.
+ You may need to override this if you are using custom levels, or
+ if the default algorithm is not suitable for your needs. The
+ default algorithm maps ``DEBUG``, ``INFO``, ``WARNING``, ``ERROR`` and
+ ``CRITICAL`` to the equivalent syslog names, and all other level
+ names to 'warning'.
+
+.. _nt-eventlog-handler:
+
+NTEventLogHandler
+^^^^^^^^^^^^^^^^^
+
+The :class:`NTEventLogHandler` class, located in the :mod:`logging.handlers`
+module, supports sending logging messages to a local Windows NT, Windows 2000 or
+Windows XP event log. Before you can use it, you need Mark Hammond's Win32
+extensions for Python installed.
+
+
+.. class:: NTEventLogHandler(appname, dllname=None, logtype='Application')
+
+ Returns a new instance of the :class:`NTEventLogHandler` class. The *appname* is
+ used to define the application name as it appears in the event log. An
+ appropriate registry entry is created using this name. The *dllname* should give
+ the fully qualified pathname of a .dll or .exe which contains message
+ definitions to hold in the log (if not specified, ``'win32service.pyd'`` is used
+ - this is installed with the Win32 extensions and contains some basic
+ placeholder message definitions. Note that use of these placeholders will make
+ your event logs big, as the entire message source is held in the log. If you
+ want slimmer logs, you have to pass in the name of your own .dll or .exe which
+ contains the message definitions you want to use in the event log). The
+ *logtype* is one of ``'Application'``, ``'System'`` or ``'Security'``, and
+ defaults to ``'Application'``.
+
+
+ .. method:: close()
+
+ At this point, you can remove the application name from the registry as a
+ source of event log entries. However, if you do this, you will not be able
+ to see the events as you intended in the Event Log Viewer - it needs to be
+ able to access the registry to get the .dll name. The current version does
+ not do this.
+
+
+ .. method:: emit(record)
+
+ Determines the message ID, event category and event type, and then logs
+ the message in the NT event log.
+
+
+ .. method:: getEventCategory(record)
+
+ Returns the event category for the record. Override this if you want to
+ specify your own categories. This version returns 0.
+
+
+ .. method:: getEventType(record)
+
+ Returns the event type for the record. Override this if you want to
+ specify your own types. This version does a mapping using the handler's
+ typemap attribute, which is set up in :meth:`__init__` to a dictionary
+ which contains mappings for :const:`DEBUG`, :const:`INFO`,
+ :const:`WARNING`, :const:`ERROR` and :const:`CRITICAL`. If you are using
+ your own levels, you will either need to override this method or place a
+ suitable dictionary in the handler's *typemap* attribute.
+
+
+ .. method:: getMessageID(record)
+
+ Returns the message ID for the record. If you are using your own messages,
+ you could do this by having the *msg* passed to the logger being an ID
+ rather than a format string. Then, in here, you could use a dictionary
+ lookup to get the message ID. This version returns 1, which is the base
+ message ID in :file:`win32service.pyd`.
+
+.. _smtp-handler:
+
+SMTPHandler
+^^^^^^^^^^^
+
+The :class:`SMTPHandler` class, located in the :mod:`logging.handlers` module,
+supports sending logging messages to an email address via SMTP.
+
+
+.. class:: SMTPHandler(mailhost, fromaddr, toaddrs, subject, credentials=None)
+
+ Returns a new instance of the :class:`SMTPHandler` class. The instance is
+ initialized with the from and to addresses and subject line of the email. The
+ *toaddrs* should be a list of strings. To specify a non-standard SMTP port, use
+ the (host, port) tuple format for the *mailhost* argument. If you use a string,
+ the standard SMTP port is used. If your SMTP server requires authentication, you
+ can specify a (username, password) tuple for the *credentials* argument.
+
+
+ .. method:: emit(record)
+
+ Formats the record and sends it to the specified addressees.
+
+
+ .. method:: getSubject(record)
+
+ If you want to specify a subject line which is record-dependent, override
+ this method.
+
+.. _memory-handler:
+
+MemoryHandler
+^^^^^^^^^^^^^
+
+The :class:`MemoryHandler` class, located in the :mod:`logging.handlers` module,
+supports buffering of logging records in memory, periodically flushing them to a
+:dfn:`target` handler. Flushing occurs whenever the buffer is full, or when an
+event of a certain severity or greater is seen.
+
+:class:`MemoryHandler` is a subclass of the more general
+:class:`BufferingHandler`, which is an abstract class. This buffers logging
+records in memory. Whenever each record is added to the buffer, a check is made
+by calling :meth:`shouldFlush` to see if the buffer should be flushed. If it
+should, then :meth:`flush` is expected to do the needful.
+
+
+.. class:: BufferingHandler(capacity)
+
+ Initializes the handler with a buffer of the specified capacity.
+
+
+ .. method:: emit(record)
+
+ Appends the record to the buffer. If :meth:`shouldFlush` returns true,
+ calls :meth:`flush` to process the buffer.
+
+
+ .. method:: flush()
+
+ You can override this to implement custom flushing behavior. This version
+ just zaps the buffer to empty.
+
+
+ .. method:: shouldFlush(record)
+
+ Returns true if the buffer is up to capacity. This method can be
+ overridden to implement custom flushing strategies.
+
+
+.. class:: MemoryHandler(capacity, flushLevel=ERROR, target=None)
+
+ Returns a new instance of the :class:`MemoryHandler` class. The instance is
+ initialized with a buffer size of *capacity*. If *flushLevel* is not specified,
+ :const:`ERROR` is used. If no *target* is specified, the target will need to be
+ set using :meth:`setTarget` before this handler does anything useful.
+
+
+ .. method:: close()
+
+ Calls :meth:`flush`, sets the target to :const:`None` and clears the
+ buffer.
+
+
+ .. method:: flush()
+
+ For a :class:`MemoryHandler`, flushing means just sending the buffered
+ records to the target, if there is one. The buffer is also cleared when
+ this happens. Override if you want different behavior.
+
+
+ .. method:: setTarget(target)
+
+ Sets the target handler for this handler.
+
+
+ .. method:: shouldFlush(record)
+
+ Checks for buffer full or a record at the *flushLevel* or higher.
+
+
+.. _http-handler:
+
+HTTPHandler
+^^^^^^^^^^^
+
+The :class:`HTTPHandler` class, located in the :mod:`logging.handlers` module,
+supports sending logging messages to a Web server, using either ``GET`` or
+``POST`` semantics.
+
+
+.. class:: HTTPHandler(host, url, method='GET', secure=False, credentials=None)
+
+ Returns a new instance of the :class:`HTTPHandler` class. The *host* can be
+ of the form ``host:port``, should you need to use a specific port number.
+ If no *method* is specified, ``GET`` is used. If *secure* is True, an HTTPS
+ connection will be used. If *credentials* is specified, it should be a
+ 2-tuple consisting of userid and password, which will be placed in an HTTP
+ 'Authorization' header using Basic authentication. If you specify
+ credentials, you should also specify secure=True so that your userid and
+ password are not passed in cleartext across the wire.
+
+
+ .. method:: emit(record)
+
+ Sends the record to the Web server as a percent-encoded dictionary.
+
+
+.. _queue-handler:
+
+
+QueueHandler
+^^^^^^^^^^^^
+
+.. versionadded:: 3.2
+
+The :class:`QueueHandler` class, located in the :mod:`logging.handlers` module,
+supports sending logging messages to a queue, such as those implemented in the
+:mod:`queue` or :mod:`multiprocessing` modules.
+
+Along with the :class:`QueueListener` class, :class:`QueueHandler` can be used
+to let handlers do their work on a separate thread from the one which does the
+logging. This is important in Web applications and also other service
+applications where threads servicing clients need to respond as quickly as
+possible, while any potentially slow operations (such as sending an email via
+:class:`SMTPHandler`) are done on a separate thread.
+
+.. class:: QueueHandler(queue)
+
+ Returns a new instance of the :class:`QueueHandler` class. The instance is
+ initialized with the queue to send messages to. The queue can be any queue-
+ like object; it's used as-is by the :meth:`enqueue` method, which needs
+ to know how to send messages to it.
+
+
+ .. method:: emit(record)
+
+ Enqueues the result of preparing the LogRecord.
+
+ .. method:: prepare(record)
+
+ Prepares a record for queuing. The object returned by this
+ method is enqueued.
+
+ The base implementation formats the record to merge the message
+ and arguments, and removes unpickleable items from the record
+ in-place.
+
+ You might want to override this method if you want to convert
+ the record to a dict or JSON string, or send a modified copy
+ of the record while leaving the original intact.
+
+ .. method:: enqueue(record)
+
+ Enqueues the record on the queue using ``put_nowait()``; you may
+ want to override this if you want to use blocking behaviour, or a
+ timeout, or a customised queue implementation.
+
+
+
+.. queue-listener:
+
+QueueListener
+^^^^^^^^^^^^^
+
+.. versionadded:: 3.2
+
+The :class:`QueueListener` class, located in the :mod:`logging.handlers`
+module, supports receiving logging messages from a queue, such as those
+implemented in the :mod:`queue` or :mod:`multiprocessing` modules. The
+messages are received from a queue in an internal thread and passed, on
+the same thread, to one or more handlers for processing. While
+:class:`QueueListener` is not itself a handler, it is documented here
+because it works hand-in-hand with :class:`QueueHandler`.
+
+Along with the :class:`QueueHandler` class, :class:`QueueListener` can be used
+to let handlers do their work on a separate thread from the one which does the
+logging. This is important in Web applications and also other service
+applications where threads servicing clients need to respond as quickly as
+possible, while any potentially slow operations (such as sending an email via
+:class:`SMTPHandler`) are done on a separate thread.
+
+.. class:: QueueListener(queue, *handlers)
+
+ Returns a new instance of the :class:`QueueListener` class. The instance is
+ initialized with the queue to send messages to and a list of handlers which
+ will handle entries placed on the queue. The queue can be any queue-
+ like object; it's passed as-is to the :meth:`dequeue` method, which needs
+ to know how to get messages from it.
+
+ .. method:: dequeue(block)
+
+ Dequeues a record and return it, optionally blocking.
+
+ The base implementation uses ``get()``. You may want to override this
+ method if you want to use timeouts or work with custom queue
+ implementations.
+
+ .. method:: prepare(record)
+
+ Prepare a record for handling.
+
+ This implementation just returns the passed-in record. You may want to
+ override this method if you need to do any custom marshalling or
+ manipulation of the record before passing it to the handlers.
+
+ .. method:: handle(record)
+
+ Handle a record.
+
+ This just loops through the handlers offering them the record
+ to handle. The actual object passed to the handlers is that which
+ is returned from :meth:`prepare`.
+
+ .. method:: start()
+
+ Starts the listener.
+
+ This starts up a background thread to monitor the queue for
+ LogRecords to process.
+
+ .. method:: stop()
+
+ Stops the listener.
+
+ This asks the thread to terminate, and then waits for it to do so.
+ Note that if you don't call this before your application exits, there
+ may be some records still left on the queue, which won't be processed.
+
+
+.. seealso::
+
+ Module :mod:`logging`
+ API reference for the logging module.
+
+ Module :mod:`logging.config`
+ Configuration API for the logging module.
+
+
diff --git a/Doc/library/logging.rst b/Doc/library/logging.rst
index 25a2549..4eb39d4 100644
--- a/Doc/library/logging.rst
+++ b/Doc/library/logging.rst
@@ -11,6 +11,16 @@
.. index:: pair: Errors; logging
+.. sidebar:: Important
+
+ The tutorials have been moved to the HOWTO section:
+
+ * :ref:`Basic Tutorial <logging-basic-tutorial>`
+ * :ref:`Advanced Tutorial <logging-advanced-tutorial>`
+ * :ref:`Logging Cookbook <logging-cookbook>`
+
+
+
This module defines functions and classes which implement a flexible event
logging system for applications and libraries.
@@ -19,326 +29,13 @@ is that all Python modules can participate in logging, so your application log
can include your own messages integrated with messages from third-party
modules.
+The module provides a lot of functionality and flexibility. If you are
+unfamiliar with logging, the best way to get to grips with it is to see the
+tutorials (see the links on the right). This page contains the API reference
+information.
-Logging tutorial
-----------------
-
-Logging is a means of tracking events that happen when some software runs. The
-software's developer adds logging calls to their code to indicate that certain
-events have occurred. An event is described by a descriptive message which can
-optionally contain variable data (i.e. data that is potentially different for
-each occurrence of the event). Events also have an importance which the
-developer ascribes to the event; the importance can also be called the *level*
-or *severity*.
-
-When to use logging
-^^^^^^^^^^^^^^^^^^^
-
-Logging provides a set of convenience functions for simple logging usage. These
-are :func:`debug`, :func:`info`, :func:`warning`, :func:`error` and
-:func:`critical`. To determine when to use logging, see the table below, which
-states, for each of a set of common tasks, the best tool to use for it.
-
-+-------------------------------------+--------------------------------------+
-| Task you want to perform | The best tool for the task |
-+=====================================+======================================+
-| Display console output for ordinary | :func:`print` |
-| usage of a command line script or | |
-| program | |
-+-------------------------------------+--------------------------------------+
-| Report events that occur during | :func:`logging.info` (or |
-| normal operation of a program (e.g. | :func:`logging.debug` for very |
-| for status monitoring or fault | detailed output for diagnostic |
-| investigation) | purposes) |
-+-------------------------------------+--------------------------------------+
-| Issue a warning regarding a | :func:`warnings.warn` in library |
-| particular runtime event | code if the issue is avoidable and |
-| | the client application should be |
-| | modified to eliminate the warning |
-| | |
-| | :func:`logging.warning` if there is |
-| | nothing the client application can do|
-| | about the situation, but the event |
-| | should still be noted |
-+-------------------------------------+--------------------------------------+
-| Report an error regarding a | Raise an exception |
-| particular runtime event | |
-+-------------------------------------+--------------------------------------+
-| Report suppression of an error | :func:`logging.error`, |
-| without raising an exception (e.g. | :func:`logging.exception` or |
-| error handler in a long-running | :func:`logging.critical` as |
-| server process) | appropriate for the specific error |
-| | and application domain |
-+-------------------------------------+--------------------------------------+
-
-The logging functions are named after the level or severity of the events
-they are used to track. The standard levels and their applicability are
-described below (in increasing order of severity):
-
-+--------------+---------------------------------------------+
-| Level | When it's used |
-+==============+=============================================+
-| ``DEBUG`` | Detailed information, typically of interest |
-| | only when diagnosing problems. |
-+--------------+---------------------------------------------+
-| ``INFO`` | Confirmation that things are working as |
-| | expected. |
-+--------------+---------------------------------------------+
-| ``WARNING`` | An indication that something unexpected |
-| | happened, or indicative of some problem in |
-| | the near future (e.g. 'disk space low'). |
-| | The software is still working as expected. |
-+--------------+---------------------------------------------+
-| ``ERROR`` | Due to a more serious problem, the software |
-| | has not been able to perform some function. |
-+--------------+---------------------------------------------+
-| ``CRITICAL`` | A serious error, indicating that the program|
-| | itself may be unable to continue running. |
-+--------------+---------------------------------------------+
-
-The default level is ``WARNING``, which means that only events of this level
-and above will be tracked, unless the logging package is configured to do
-otherwise.
-
-Events that are tracked can be handled in different ways. The simplest way of
-handling tracked events is to print them to the console. Another common way
-is to write them to a disk file.
-
-
-.. _minimal-example:
-
-A simple example
-^^^^^^^^^^^^^^^^
-
-A very simple example is::
-
- import logging
- logging.warning('Watch out!') # will print a message to the console
- logging.info('I told you so') # will not print anything
-
-If you type these lines into a script and run it, you'll see::
-
- WARNING:root:Watch out!
-
-printed out on the console. The ``INFO`` message doesn't appear because the
-default level is ``WARNING``. The printed message includes the indication of
-the level and the description of the event provided in the logging call, i.e.
-'Watch out!'. Don't worry about the 'root' part for now: it will be explained
-later. The actual output can be formatted quite flexibly if you need that;
-formatting options will also be explained later.
-
-
-Logging to a file
-^^^^^^^^^^^^^^^^^
-
-A very common situation is that of recording logging events in a file, so let's
-look at that next::
-
- import logging
- logging.basicConfig(filename='example.log',level=logging.DEBUG)
- logging.debug('This message should go to the log file')
- logging.info('So should this')
- logging.warning('And this, too')
-
-And now if we open the file and look at what we have, we should find the log
-messages::
-
- DEBUG:root:This message should go to the log file
- INFO:root:So should this
- WARNING:root:And this, too
-
-This example also shows how you can set the logging level which acts as the
-threshold for tracking. In this case, because we set the threshold to
-``DEBUG``, all of the messages were printed.
-
-If you want to set the logging level from a command-line option such as::
-
- --log=INFO
-
-and you have the value of the parameter passed for ``--log`` in some variable
-*loglevel*, you can use::
-
- getattr(logging, loglevel.upper())
-
-to get the value which you'll pass to :func:`basicConfig` via the *level*
-argument. You may want to error check any user input value, perhaps as in the
-following example::
-
- # assuming loglevel is bound to the string value obtained from the
- # command line argument. Convert to upper case to allow the user to
- # specify --log=DEBUG or --log=debug
- numeric_level = getattr(logging, loglevel.upper(), None)
- if not isinstance(numeric_level, int):
- raise ValueError('Invalid log level: %s' % loglevel)
- logging.basicConfig(level=numeric_level, ...)
-
-The call to :func:`basicConfig` should come *before* any calls to :func:`debug`,
-:func:`info` etc. As it's intended as a one-off simple configuration facility,
-only the first call will actually do anything: subsequent calls are effectively
-no-ops.
-
-If you run the above script several times, the messages from successive runs
-are appended to the file *example.log*. If you want each run to start afresh,
-not remembering the messages from earlier runs, you can specify the *filemode*
-argument, by changing the call in the above example to::
-
- logging.basicConfig(filename='example.log', filemode='w', level=logging.DEBUG)
-
-The output will be the same as before, but the log file is no longer appended
-to, so the messages from earlier runs are lost.
-
-
-Logging from multiple modules
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-If your program consists of multiple modules, here's an example of how you
-could organize logging in it::
-
- # myapp.py
- import logging
- import mylib
-
- def main():
- logging.basicConfig(filename='myapp.log', level=logging.INFO)
- logging.info('Started')
- mylib.do_something()
- logging.info('Finished')
-
- if __name__ == '__main__':
- main()
-
-::
-
- # mylib.py
- import logging
-
- def do_something():
- logging.info('Doing something')
-
-If you run *myapp.py*, you should see this in *myapp.log*::
-
- INFO:root:Started
- INFO:root:Doing something
- INFO:root:Finished
-
-which is hopefully what you were expecting to see. You can generalize this to
-multiple modules, using the pattern in *mylib.py*. Note that for this simple
-usage pattern, you won't know, by looking in the log file, *where* in your
-application your messages came from, apart from looking at the event
-description. If you want to track the location of your messages, you'll need
-to refer to the documentation beyond the tutorial level - see
-:ref:`more-advanced-logging`.
-
-
-Logging variable data
-^^^^^^^^^^^^^^^^^^^^^
-
-To log variable data, use a format string for the event description message and
-append the variable data as arguments. For example::
-
- import logging
- logging.warning('%s before you %s', 'Look', 'leap!')
-
-will display::
-
- WARNING:root:Look before you leap!
-
-As you can see, merging of variable data into the event description message
-uses the old, %-style of string formatting. This is for backwards
-compatibility: the logging package pre-dates newer formatting options such as
-:meth:`str.format` and :class:`string.Template`. These newer formatting
-options *are* supported, but exploring them is outside the scope of this
-tutorial.
-
-
-Changing the format of displayed messages
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-To change the format which is used to display messages, you need to
-specify the format you want to use::
-
- import logging
- logging.basicConfig(format='%(levelname)s:%(message)s', level=logging.DEBUG)
- logging.debug('This message should appear on the console')
- logging.info('So should this')
- logging.warning('And this, too')
-
-which would print::
-
- DEBUG:This message should appear on the console
- INFO:So should this
- WARNING:And this, too
-
-Notice that the 'root' which appeared in earlier examples has disappeared. For
-a full set of things that can appear in format strings, you can refer to the
-documentation for :ref:`logrecord-attributes`, but for simple usage, you just
-need the *levelname* (severity), *message* (event description, including
-variable data) and perhaps to display when the event occurred. This is
-described in the next section.
-
-
-Displaying the date/time in messages
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-To display the date and time of an event, you would place '%(asctime)s' in
-your format string::
-
- import logging
- logging.basicConfig(format='%(asctime)s %(message)s')
- logging.warning('is when this event was logged.')
-
-which should print something like this::
-
- 2010-12-12 11:41:42,612 is when this event was logged.
-
-The default format for date/time display (shown above) is ISO8601. If you need
-more control over the formatting of the date/time, provide a *datefmt*
-argument to ``basicConfig``, as in this example::
-
- import logging
- logging.basicConfig(format='%(asctime)s %(message)s', datefmt='%m/%d/%Y %I:%M:%S %p')
- logging.warning('is when this event was logged.')
-
-which would display something like this::
-
- 12/12/2010 11:46:36 AM is when this event was logged.
-
-The format of the *datefmt* argument is the same as supported by
-:func:`time.strftime`.
-
-
-Er...that's it for the basics
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-That concludes the basic tutorial. It should be enough to get you up and
-running with logging. There's a lot more that the logging package offers, but
-to get the best out of it, you'll need to invest a little more of your time in
-reading the following sections. If you're ready for that, grab some of your
-favourite beverage and carry on.
-
-If your logging needs are simple, then use the above examples to incorporate
-logging into your own scripts, and if you run into problems or don't
-understand something, please post a question on the comp.lang.python Usenet
-group (available at http://groups.google.com/group/comp.lang.python) and you
-should receive help before too long.
-
-Still here? There's no need to read the whole of the logging documentation in
-linear fashion, top to bottom (there's quite a lot of it still to come). You
-can carry on reading the next few sections, which provide a slightly more
-advanced/in-depth tutorial than the basic one above. After that, you can
-take a look at the topics in the sidebar to see if there's something that
-especially interests you, and click on a topic to see more detail. Although
-some of the topics do follow on from each other, there are a few that can just
-stand alone.
-
-
-.. _more-advanced-logging:
-
-More advanced logging
----------------------
-
-The logging library takes a modular approach and offers several categories
-of components: loggers, handlers, filters, and formatters.
+The basic classes defined by the module, together with their functions, are
+listed below.
* Loggers expose the interface that application code directly uses.
* Handlers send the log records (created by loggers) to the appropriate
@@ -347,916 +44,6 @@ of components: loggers, handlers, filters, and formatters.
to output.
* Formatters specify the layout of log records in the final output.
-Logging is performed by calling methods on instances of the :class:`Logger`
-class (hereafter called :dfn:`loggers`). Each instance has a name, and they are
-conceptually arranged in a namespace hierarchy using dots (periods) as
-separators. For example, a logger named 'scan' is the parent of loggers
-'scan.text', 'scan.html' and 'scan.pdf'. Logger names can be anything you want,
-and indicate the area of an application in which a logged message originates.
-
-A good convention to use when naming loggers is to use a module-level logger,
-in each module which uses logging, named as follows::
-
- logger = logging.getLogger(__name__)
-
-This means that logger names track the package/module hierarchy, and it's
-intuitively obvious where events are logged just from the logger name.
-
-The root of the hierarchy of loggers is called the root logger. That's the
-logger used by the functions :func:`debug`, :func:`info`, :func:`warning`,
-:func:`error` and :func:`critical`, which just call the same-named method of
-the root logger. The functions and the methods have the same signatures. The
-root logger's name is printed as 'root' in the logged output.
-
-It is, of course, possible to log messages to different destinations. Support
-is included in the package for writing log messages to files, HTTP GET/POST
-locations, email via SMTP, generic sockets, queues, or OS-specific logging
-mechanisms such as syslog or the Windows NT event log. Destinations are served
-by :dfn:`handler` classes. You can create your own log destination class if
-you have special requirements not met by any of the built-in handler classes.
-
-By default, no destination is set for any logging messages. You can specify
-a destination (such as console or file) by using :func:`basicConfig` as in the
-tutorial examples. If you call the functions :func:`debug`, :func:`info`,
-:func:`warning`, :func:`error` and :func:`critical`, they will check to see
-if no destination is set; and if one is not set, they will set a destination
-of the console (``sys.stderr``) and a default format for the displayed
-message before delegating to the root logger to do the actual message output.
-
-The default format set by :func:`basicConfig` for messages is::
-
- severity:logger name:message
-
-You can change this by passing a format string to :func:`basicConfig` with the
-*format* keyword argument. For all options regarding how a format string is
-constructed, see :ref:`formatter-objects`.
-
-
-Loggers
-^^^^^^^
-
-:class:`Logger` objects have a threefold job. First, they expose several
-methods to application code so that applications can log messages at runtime.
-Second, logger objects determine which log messages to act upon based upon
-severity (the default filtering facility) or filter objects. Third, logger
-objects pass along relevant log messages to all interested log handlers.
-
-The most widely used methods on logger objects fall into two categories:
-configuration and message sending.
-
-These are the most common configuration methods:
-
-* :meth:`Logger.setLevel` specifies the lowest-severity log message a logger
- will handle, where debug is the lowest built-in severity level and critical
- is the highest built-in severity. For example, if the severity level is
- INFO, the logger will handle only INFO, WARNING, ERROR, and CRITICAL messages
- and will ignore DEBUG messages.
-
-* :meth:`Logger.addHandler` and :meth:`Logger.removeHandler` add and remove
- handler objects from the logger object. Handlers are covered in more detail
- in :ref:`handler-basic`.
-
-* :meth:`Logger.addFilter` and :meth:`Logger.removeFilter` add and remove filter
- objects from the logger object. Filters are covered in more detail in
- :ref:`filter`.
-
-You don't need to always call these methods on every logger you create. See the
-last two paragraphs in this section.
-
-With the logger object configured, the following methods create log messages:
-
-* :meth:`Logger.debug`, :meth:`Logger.info`, :meth:`Logger.warning`,
- :meth:`Logger.error`, and :meth:`Logger.critical` all create log records with
- a message and a level that corresponds to their respective method names. The
- message is actually a format string, which may contain the standard string
- substitution syntax of :const:`%s`, :const:`%d`, :const:`%f`, and so on. The
- rest of their arguments is a list of objects that correspond with the
- substitution fields in the message. With regard to :const:`**kwargs`, the
- logging methods care only about a keyword of :const:`exc_info` and use it to
- determine whether to log exception information.
-
-* :meth:`Logger.exception` creates a log message similar to
- :meth:`Logger.error`. The difference is that :meth:`Logger.exception` dumps a
- stack trace along with it. Call this method only from an exception handler.
-
-* :meth:`Logger.log` takes a log level as an explicit argument. This is a
- little more verbose for logging messages than using the log level convenience
- methods listed above, but this is how to log at custom log levels.
-
-:func:`getLogger` returns a reference to a logger instance with the specified
-name if it is provided, or ``root`` if not. The names are period-separated
-hierarchical structures. Multiple calls to :func:`getLogger` with the same name
-will return a reference to the same logger object. Loggers that are further
-down in the hierarchical list are children of loggers higher up in the list.
-For example, given a logger with a name of ``foo``, loggers with names of
-``foo.bar``, ``foo.bar.baz``, and ``foo.bam`` are all descendants of ``foo``.
-
-Loggers have a concept of *effective level*. If a level is not explicitly set
-on a logger, the level of its parent is used instead as its effective level.
-If the parent has no explicit level set, *its* parent is examined, and so on -
-all ancestors are searched until an explicitly set level is found. The root
-logger always has an explicit level set (``WARNING`` by default). When deciding
-whether to process an event, the effective level of the logger is used to
-determine whether the event is passed to the logger's handlers.
-
-Child loggers propagate messages up to the handlers associated with their
-ancestor loggers. Because of this, it is unnecessary to define and configure
-handlers for all the loggers an application uses. It is sufficient to
-configure handlers for a top-level logger and create child loggers as needed.
-(You can, however, turn off propagation by setting the *propagate*
-attribute of a logger to *False*.)
-
-
-.. _handler-basic:
-
-Handlers
-^^^^^^^^
-
-:class:`Handler` objects are responsible for dispatching the appropriate log
-messages (based on the log messages' severity) to the handler's specified
-destination. Logger objects can add zero or more handler objects to themselves
-with an :func:`addHandler` method. As an example scenario, an application may
-want to send all log messages to a log file, all log messages of error or higher
-to stdout, and all messages of critical to an email address. This scenario
-requires three individual handlers where each handler is responsible for sending
-messages of a specific severity to a specific location.
-
-The standard library includes quite a few handler types (see
-:ref:`useful-handlers`); the tutorials use mainly :class:`StreamHandler` and
-:class:`FileHandler` in its examples.
-
-There are very few methods in a handler for application developers to concern
-themselves with. The only handler methods that seem relevant for application
-developers who are using the built-in handler objects (that is, not creating
-custom handlers) are the following configuration methods:
-
-* The :meth:`Handler.setLevel` method, just as in logger objects, specifies the
- lowest severity that will be dispatched to the appropriate destination. Why
- are there two :func:`setLevel` methods? The level set in the logger
- determines which severity of messages it will pass to its handlers. The level
- set in each handler determines which messages that handler will send on.
-
-* :func:`setFormatter` selects a Formatter object for this handler to use.
-
-* :func:`addFilter` and :func:`removeFilter` respectively configure and
- deconfigure filter objects on handlers.
-
-Application code should not directly instantiate and use instances of
-:class:`Handler`. Instead, the :class:`Handler` class is a base class that
-defines the interface that all handlers should have and establishes some
-default behavior that child classes can use (or override).
-
-
-Formatters
-^^^^^^^^^^
-
-Formatter objects configure the final order, structure, and contents of the log
-message. Unlike the base :class:`logging.Handler` class, application code may
-instantiate formatter classes, although you could likely subclass the formatter
-if your application needs special behavior. The constructor takes three
-optional arguments -- a message format string, a date format string and a style
-indicator.
-
-.. method:: logging.Formatter.__init__(fmt=None, datefmt=None, style='%')
-
-If there is no message format string, the default is to use the
-raw message. If there is no date format string, the default date format is::
-
- %Y-%m-%d %H:%M:%S
-
-with the milliseconds tacked on at the end. The ``style`` is one of `%`, '{'
-or '$'. If one of these is not specified, then '%' will be used.
-
-If the ``style`` is '%', the message format string uses
-``%(<dictionary key>)s`` styled string substitution; the possible keys are
-documented in :ref:`logrecord-attributes`. If the style is '{', the message
-format string is assumed to be compatible with :meth:`str.format` (using
-keyword arguments), while if the style is '$' then the message format string
-should conform to what is expected by :meth:`string.Template.substitute`.
-
-.. versionchanged:: 3.2
- Added the ``style`` parameter.
-
-The following message format string will log the time in a human-readable
-format, the severity of the message, and the contents of the message, in that
-order::
-
- '%(asctime)s - %(levelname)s - %(message)s'
-
-Formatters use a user-configurable function to convert the creation time of a
-record to a tuple. By default, :func:`time.localtime` is used; to change this
-for a particular formatter instance, set the ``converter`` attribute of the
-instance to a function with the same signature as :func:`time.localtime` or
-:func:`time.gmtime`. To change it for all formatters, for example if you want
-all logging times to be shown in GMT, set the ``converter`` attribute in the
-Formatter class (to ``time.gmtime`` for GMT display).
-
-
-Configuring Logging
-^^^^^^^^^^^^^^^^^^^
-
-Programmers can configure logging in three ways:
-
-1. Creating loggers, handlers, and formatters explicitly using Python
- code that calls the configuration methods listed above.
-2. Creating a logging config file and reading it using the :func:`fileConfig`
- function.
-3. Creating a dictionary of configuration information and passing it
- to the :func:`dictConfig` function.
-
-For the reference documentation on the last two options, see :ref:`config-ref`.
-The following example configures a very simple logger, a console handler, and
-a simple formatter using Python code::
-
- import logging
-
- # create logger
- logger = logging.getLogger('simple_example')
- logger.setLevel(logging.DEBUG)
-
- # create console handler and set level to debug
- ch = logging.StreamHandler()
- ch.setLevel(logging.DEBUG)
-
- # create formatter
- formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
-
- # add formatter to ch
- ch.setFormatter(formatter)
-
- # add ch to logger
- logger.addHandler(ch)
-
- # 'application' code
- logger.debug('debug message')
- logger.info('info message')
- logger.warn('warn message')
- logger.error('error message')
- logger.critical('critical message')
-
-Running this module from the command line produces the following output::
-
- $ python simple_logging_module.py
- 2005-03-19 15:10:26,618 - simple_example - DEBUG - debug message
- 2005-03-19 15:10:26,620 - simple_example - INFO - info message
- 2005-03-19 15:10:26,695 - simple_example - WARNING - warn message
- 2005-03-19 15:10:26,697 - simple_example - ERROR - error message
- 2005-03-19 15:10:26,773 - simple_example - CRITICAL - critical message
-
-The following Python module creates a logger, handler, and formatter nearly
-identical to those in the example listed above, with the only difference being
-the names of the objects::
-
- import logging
- import logging.config
-
- logging.config.fileConfig('logging.conf')
-
- # create logger
- logger = logging.getLogger('simpleExample')
-
- # 'application' code
- logger.debug('debug message')
- logger.info('info message')
- logger.warn('warn message')
- logger.error('error message')
- logger.critical('critical message')
-
-Here is the logging.conf file::
-
- [loggers]
- keys=root,simpleExample
-
- [handlers]
- keys=consoleHandler
-
- [formatters]
- keys=simpleFormatter
-
- [logger_root]
- level=DEBUG
- handlers=consoleHandler
-
- [logger_simpleExample]
- level=DEBUG
- handlers=consoleHandler
- qualname=simpleExample
- propagate=0
-
- [handler_consoleHandler]
- class=StreamHandler
- level=DEBUG
- formatter=simpleFormatter
- args=(sys.stdout,)
-
- [formatter_simpleFormatter]
- format=%(asctime)s - %(name)s - %(levelname)s - %(message)s
- datefmt=
-
-The output is nearly identical to that of the non-config-file-based example::
-
- $ python simple_logging_config.py
- 2005-03-19 15:38:55,977 - simpleExample - DEBUG - debug message
- 2005-03-19 15:38:55,979 - simpleExample - INFO - info message
- 2005-03-19 15:38:56,054 - simpleExample - WARNING - warn message
- 2005-03-19 15:38:56,055 - simpleExample - ERROR - error message
- 2005-03-19 15:38:56,130 - simpleExample - CRITICAL - critical message
-
-You can see that the config file approach has a few advantages over the Python
-code approach, mainly separation of configuration and code and the ability of
-noncoders to easily modify the logging properties.
-
-Note that the class names referenced in config files need to be either relative
-to the logging module, or absolute values which can be resolved using normal
-import mechanisms. Thus, you could use either
-:class:`handlers.WatchedFileHandler` (relative to the logging module) or
-``mypackage.mymodule.MyHandler`` (for a class defined in package ``mypackage``
-and module ``mymodule``, where ``mypackage`` is available on the Python import
-path).
-
-In Python 3.2, a new means of configuring logging has been introduced, using
-dictionaries to hold configuration information. This provides a superset of the
-functionality of the config-file-based approach outlined above, and is the
-recommended configuration method for new applications and deployments. Because
-a Python dictionary is used to hold configuration information, and since you
-can populate that dictionary using different means, you have more options for
-configuration. For example, you can use a configuration file in JSON format,
-or, if you have access to YAML processing functionality, a file in YAML
-format, to populate the configuration dictionary. Or, of course, you can
-construct the dictionary in Python code, receive it in pickled form over a
-socket, or use whatever approach makes sense for your application.
-
-Here's an example of the same configuration as above, in YAML format for
-the new dictionary-based approach::
-
- version: 1
- formatters:
- simple:
- format: format=%(asctime)s - %(name)s - %(levelname)s - %(message)s
- handlers:
- console:
- class: logging.StreamHandler
- level: DEBUG
- formatter: simple
- stream: ext://sys.stdout
- loggers:
- simpleExample:
- level: DEBUG
- handlers: [console]
- propagate: no
- root:
- level: DEBUG
- handlers: [console]
-
-For more information about logging using a dictionary, see
-:ref:`logging-config-api`.
-
-What happens if no configuration is provided
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-If no logging configuration is provided, it is possible to have a situation
-where a logging event needs to be output, but no handlers can be found to
-output the event. The behaviour of the logging package in these
-circumstances is dependent on the Python version.
-
-For versions of Python prior to 3.2, the behaviour is as follows:
-
-* If *logging.raiseExceptions* is *False* (production mode), the event is
- silently dropped.
-
-* If *logging.raiseExceptions* is *True* (development mode), a message
- 'No handlers could be found for logger X.Y.Z' is printed once.
-
-In Python 3.2 and later, the behaviour is as follows:
-
-* The event is output using a 'handler of last resort', stored in
- ``logging.lastResort``. This internal handler is not associated with any
- logger, and acts like a :class:`StreamHandler` which writes the event
- description message to the current value of ``sys.stderr`` (therefore
- respecting any redirections which may be in effect). No formatting is
- done on the message - just the bare event description message is printed.
- The handler's level is set to ``WARNING``, so all events at this and
- greater severities will be output.
-
-To obtain the pre-3.2 behaviour, ``logging.lastResort`` can be set to *None*.
-
-.. _library-config:
-
-Configuring Logging for a Library
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-When developing a library which uses logging, you should take care to
-document how the library uses logging - for example, the names of loggers
-used. Some consideration also needs to be given to its logging configuration.
-If the using application does not use logging, and library code makes logging
-calls, then (as described in the previous section) events of severity
-``WARNING`` and greater will be printed to ``sys.stderr``. This is regarded as
-the best default behaviour.
-
-If for some reason you *don't* want these messages printed in the absence of
-any logging configuration, you can attach a do-nothing handler to the top-level
-logger for your library. This avoids the message being printed, since a handler
-will be always be found for the library's events: it just doesn't produce any
-output. If the library user configures logging for application use, presumably
-that configuration will add some handlers, and if levels are suitably
-configured then logging calls made in library code will send output to those
-handlers, as normal.
-
-A do-nothing handler is included in the logging package: :class:`NullHandler`
-(since Python 3.1). An instance of this handler could be added to the top-level
-logger of the logging namespace used by the library (*if* you want to prevent
-your library's logged events being output to ``sys.stderr`` in the absence of
-logging configuration). If all logging by a library *foo* is done using loggers
-with names matching 'foo.x', 'foo.x.y', etc. then the code::
-
- import logging
- logging.getLogger('foo').addHandler(logging.NullHandler())
-
-should have the desired effect. If an organisation produces a number of
-libraries, then the logger name specified can be 'orgname.foo' rather than
-just 'foo'.
-
-**PLEASE NOTE:** It is strongly advised that you *do not add any handlers other
-than* :class:`NullHandler` *to your library's loggers*. This is because the
-configuration of handlers is the prerogative of the application developer who
-uses your library. The application developer knows their target audience and
-what handlers are most appropriate for their application: if you add handlers
-'under the hood', you might well interfere with their ability to carry out
-unit tests and deliver logs which suit their requirements.
-
-
-Logging Levels
---------------
-
-The numeric values of logging levels are given in the following table. These are
-primarily of interest if you want to define your own levels, and need them to
-have specific values relative to the predefined levels. If you define a level
-with the same numeric value, it overwrites the predefined value; the predefined
-name is lost.
-
-+--------------+---------------+
-| Level | Numeric value |
-+==============+===============+
-| ``CRITICAL`` | 50 |
-+--------------+---------------+
-| ``ERROR`` | 40 |
-+--------------+---------------+
-| ``WARNING`` | 30 |
-+--------------+---------------+
-| ``INFO`` | 20 |
-+--------------+---------------+
-| ``DEBUG`` | 10 |
-+--------------+---------------+
-| ``NOTSET`` | 0 |
-+--------------+---------------+
-
-Levels can also be associated with loggers, being set either by the developer or
-through loading a saved logging configuration. When a logging method is called
-on a logger, the logger compares its own level with the level associated with
-the method call. If the logger's level is higher than the method call's, no
-logging message is actually generated. This is the basic mechanism controlling
-the verbosity of logging output.
-
-Logging messages are encoded as instances of the :class:`LogRecord` class. When
-a logger decides to actually log an event, a :class:`LogRecord` instance is
-created from the logging message.
-
-Logging messages are subjected to a dispatch mechanism through the use of
-:dfn:`handlers`, which are instances of subclasses of the :class:`Handler`
-class. Handlers are responsible for ensuring that a logged message (in the form
-of a :class:`LogRecord`) ends up in a particular location (or set of locations)
-which is useful for the target audience for that message (such as end users,
-support desk staff, system administrators, developers). Handlers are passed
-:class:`LogRecord` instances intended for particular destinations. Each logger
-can have zero, one or more handlers associated with it (via the
-:meth:`addHandler` method of :class:`Logger`). In addition to any handlers
-directly associated with a logger, *all handlers associated with all ancestors
-of the logger* are called to dispatch the message (unless the *propagate* flag
-for a logger is set to a false value, at which point the passing to ancestor
-handlers stops).
-
-Just as for loggers, handlers can have levels associated with them. A handler's
-level acts as a filter in the same way as a logger's level does. If a handler
-decides to actually dispatch an event, the :meth:`emit` method is used to send
-the message to its destination. Most user-defined subclasses of :class:`Handler`
-will need to override this :meth:`emit`.
-
-.. _custom-levels:
-
-Custom Levels
-^^^^^^^^^^^^^
-
-Defining your own levels is possible, but should not be necessary, as the
-existing levels have been chosen on the basis of practical experience.
-However, if you are convinced that you need custom levels, great care should
-be exercised when doing this, and it is possibly *a very bad idea to define
-custom levels if you are developing a library*. That's because if multiple
-library authors all define their own custom levels, there is a chance that
-the logging output from such multiple libraries used together will be
-difficult for the using developer to control and/or interpret, because a
-given numeric value might mean different things for different libraries.
-
-
-.. _useful-handlers:
-
-Useful Handlers
----------------
-
-In addition to the base :class:`Handler` class, many useful subclasses are
-provided:
-
-#. :class:`StreamHandler` instances send messages to streams (file-like
- objects).
-
-#. :class:`FileHandler` instances send messages to disk files.
-
-.. module:: logging.handlers
-
-#. :class:`BaseRotatingHandler` is the base class for handlers that
- rotate log files at a certain point. It is not meant to be instantiated
- directly. Instead, use :class:`RotatingFileHandler` or
- :class:`TimedRotatingFileHandler`.
-
-#. :class:`RotatingFileHandler` instances send messages to disk
- files, with support for maximum log file sizes and log file rotation.
-
-#. :class:`TimedRotatingFileHandler` instances send messages to
- disk files, rotating the log file at certain timed intervals.
-
-#. :class:`SocketHandler` instances send messages to TCP/IP
- sockets.
-
-#. :class:`DatagramHandler` instances send messages to UDP
- sockets.
-
-#. :class:`SMTPHandler` instances send messages to a designated
- email address.
-
-#. :class:`SysLogHandler` instances send messages to a Unix
- syslog daemon, possibly on a remote machine.
-
-#. :class:`NTEventLogHandler` instances send messages to a
- Windows NT/2000/XP event log.
-
-#. :class:`MemoryHandler` instances send messages to a buffer
- in memory, which is flushed whenever specific criteria are met.
-
-#. :class:`HTTPHandler` instances send messages to an HTTP
- server using either ``GET`` or ``POST`` semantics.
-
-#. :class:`WatchedFileHandler` instances watch the file they are
- logging to. If the file changes, it is closed and reopened using the file
- name. This handler is only useful on Unix-like systems; Windows does not
- support the underlying mechanism used.
-
-#. :class:`QueueHandler` instances send messages to a queue, such as
- those implemented in the :mod:`queue` or :mod:`multiprocessing` modules.
-
-.. currentmodule:: logging
-
-#. :class:`NullHandler` instances do nothing with error messages. They are used
- by library developers who want to use logging, but want to avoid the 'No
- handlers could be found for logger XXX' message which can be displayed if
- the library user has not configured logging. See :ref:`library-config` for
- more information.
-
-.. versionadded:: 3.1
- The :class:`NullHandler` class.
-
-.. versionadded:: 3.2
- The :class:`~logging.handlers.QueueHandler` class.
-
-The :class:`NullHandler`, :class:`StreamHandler` and :class:`FileHandler`
-classes are defined in the core logging package. The other handlers are
-defined in a sub- module, :mod:`logging.handlers`. (There is also another
-sub-module, :mod:`logging.config`, for configuration functionality.)
-
-Logged messages are formatted for presentation through instances of the
-:class:`Formatter` class. They are initialized with a format string suitable for
-use with the % operator and a dictionary.
-
-For formatting multiple messages in a batch, instances of
-:class:`BufferingFormatter` can be used. In addition to the format string (which
-is applied to each message in the batch), there is provision for header and
-trailer format strings.
-
-When filtering based on logger level and/or handler level is not enough,
-instances of :class:`Filter` can be added to both :class:`Logger` and
-:class:`Handler` instances (through their :meth:`addFilter` method). Before
-deciding to process a message further, both loggers and handlers consult all
-their filters for permission. If any filter returns a false value, the message
-is not processed further.
-
-The basic :class:`Filter` functionality allows filtering by specific logger
-name. If this feature is used, messages sent to the named logger and its
-children are allowed through the filter, and all others dropped.
-
-Module-Level Functions
-----------------------
-
-In addition to the classes described above, there are a number of module- level
-functions.
-
-
-.. function:: getLogger(name=None)
-
- Return a logger with the specified name or, if name is ``None``, return a
- logger which is the root logger of the hierarchy. If specified, the name is
- typically a dot-separated hierarchical name like *'a'*, *'a.b'* or *'a.b.c.d'*.
- Choice of these names is entirely up to the developer who is using logging.
-
- All calls to this function with a given name return the same logger instance.
- This means that logger instances never need to be passed between different parts
- of an application.
-
-
-.. function:: getLoggerClass()
-
- Return either the standard :class:`Logger` class, or the last class passed to
- :func:`setLoggerClass`. This function may be called from within a new class
- definition, to ensure that installing a customised :class:`Logger` class will
- not undo customisations already applied by other code. For example::
-
- class MyLogger(logging.getLoggerClass()):
- # ... override behaviour here
-
-
-.. function:: getLogRecordFactory()
-
- Return a callable which is used to create a :class:`LogRecord`.
-
- .. versionadded:: 3.2
- This function has been provided, along with :func:`setLogRecordFactory`,
- to allow developers more control over how the :class:`LogRecord`
- representing a logging event is constructed.
-
- See :func:`setLogRecordFactory` for more information about the how the
- factory is called.
-
-.. function:: debug(msg, *args, **kwargs)
-
- Logs a message with level :const:`DEBUG` on the root logger. The *msg* is the
- message format string, and the *args* are the arguments which are merged into
- *msg* using the string formatting operator. (Note that this means that you can
- use keywords in the format string, together with a single dictionary argument.)
-
- There are three keyword arguments in *kwargs* which are inspected: *exc_info*
- which, if it does not evaluate as false, causes exception information to be
- added to the logging message. If an exception tuple (in the format returned by
- :func:`sys.exc_info`) is provided, it is used; otherwise, :func:`sys.exc_info`
- is called to get the exception information.
-
- The second optional keyword argument is *stack_info*, which defaults to
- False. If specified as True, stack information is added to the logging
- message, including the actual logging call. Note that this is not the same
- stack information as that displayed through specifying *exc_info*: The
- former is stack frames from the bottom of the stack up to the logging call
- in the current thread, whereas the latter is information about stack frames
- which have been unwound, following an exception, while searching for
- exception handlers.
-
- You can specify *stack_info* independently of *exc_info*, e.g. to just show
- how you got to a certain point in your code, even when no exceptions were
- raised. The stack frames are printed following a header line which says::
-
- Stack (most recent call last):
-
- This mimics the `Traceback (most recent call last):` which is used when
- displaying exception frames.
-
- The third optional keyword argument is *extra* which can be used to pass a
- dictionary which is used to populate the __dict__ of the LogRecord created for
- the logging event with user-defined attributes. These custom attributes can then
- be used as you like. For example, they could be incorporated into logged
- messages. For example::
-
- FORMAT = '%(asctime)-15s %(clientip)s %(user)-8s %(message)s'
- logging.basicConfig(format=FORMAT)
- d = {'clientip': '192.168.0.1', 'user': 'fbloggs'}
- logging.warning('Protocol problem: %s', 'connection reset', extra=d)
-
- would print something like::
-
- 2006-02-08 22:20:02,165 192.168.0.1 fbloggs Protocol problem: connection reset
-
- The keys in the dictionary passed in *extra* should not clash with the keys used
- by the logging system. (See the :class:`Formatter` documentation for more
- information on which keys are used by the logging system.)
-
- If you choose to use these attributes in logged messages, you need to exercise
- some care. In the above example, for instance, the :class:`Formatter` has been
- set up with a format string which expects 'clientip' and 'user' in the attribute
- dictionary of the LogRecord. If these are missing, the message will not be
- logged because a string formatting exception will occur. So in this case, you
- always need to pass the *extra* dictionary with these keys.
-
- While this might be annoying, this feature is intended for use in specialized
- circumstances, such as multi-threaded servers where the same code executes in
- many contexts, and interesting conditions which arise are dependent on this
- context (such as remote client IP address and authenticated user name, in the
- above example). In such circumstances, it is likely that specialized
- :class:`Formatter`\ s would be used with particular :class:`Handler`\ s.
-
- .. versionadded:: 3.2
- The *stack_info* parameter was added.
-
-.. function:: info(msg, *args, **kwargs)
-
- Logs a message with level :const:`INFO` on the root logger. The arguments are
- interpreted as for :func:`debug`.
-
-
-.. function:: warning(msg, *args, **kwargs)
-
- Logs a message with level :const:`WARNING` on the root logger. The arguments are
- interpreted as for :func:`debug`.
-
-
-.. function:: error(msg, *args, **kwargs)
-
- Logs a message with level :const:`ERROR` on the root logger. The arguments are
- interpreted as for :func:`debug`.
-
-
-.. function:: critical(msg, *args, **kwargs)
-
- Logs a message with level :const:`CRITICAL` on the root logger. The arguments
- are interpreted as for :func:`debug`.
-
-
-.. function:: exception(msg, *args)
-
- Logs a message with level :const:`ERROR` on the root logger. The arguments are
- interpreted as for :func:`debug`. Exception info is added to the logging
- message. This function should only be called from an exception handler.
-
-.. function:: log(level, msg, *args, **kwargs)
-
- Logs a message with level *level* on the root logger. The other arguments are
- interpreted as for :func:`debug`.
-
- PLEASE NOTE: The above module-level functions which delegate to the root
- logger should *not* be used in threads, in versions of Python earlier than
- 2.7.1 and 3.2, unless at least one handler has been added to the root
- logger *before* the threads are started. These convenience functions call
- :func:`basicConfig` to ensure that at least one handler is available; in
- earlier versions of Python, this can (under rare circumstances) lead to
- handlers being added multiple times to the root logger, which can in turn
- lead to multiple messages for the same event.
-
-.. function:: disable(lvl)
-
- Provides an overriding level *lvl* for all loggers which takes precedence over
- the logger's own level. When the need arises to temporarily throttle logging
- output down across the whole application, this function can be useful. Its
- effect is to disable all logging calls of severity *lvl* and below, so that
- if you call it with a value of INFO, then all INFO and DEBUG events would be
- discarded, whereas those of severity WARNING and above would be processed
- according to the logger's effective level.
-
-
-.. function:: addLevelName(lvl, levelName)
-
- Associates level *lvl* with text *levelName* in an internal dictionary, which is
- used to map numeric levels to a textual representation, for example when a
- :class:`Formatter` formats a message. This function can also be used to define
- your own levels. The only constraints are that all levels used must be
- registered using this function, levels should be positive integers and they
- should increase in increasing order of severity.
-
- NOTE: If you are thinking of defining your own levels, please see the section
- on :ref:`custom-levels`.
-
-.. function:: getLevelName(lvl)
-
- Returns the textual representation of logging level *lvl*. If the level is one
- of the predefined levels :const:`CRITICAL`, :const:`ERROR`, :const:`WARNING`,
- :const:`INFO` or :const:`DEBUG` then you get the corresponding string. If you
- have associated levels with names using :func:`addLevelName` then the name you
- have associated with *lvl* is returned. If a numeric value corresponding to one
- of the defined levels is passed in, the corresponding string representation is
- returned. Otherwise, the string 'Level %s' % lvl is returned.
-
-
-.. function:: makeLogRecord(attrdict)
-
- Creates and returns a new :class:`LogRecord` instance whose attributes are
- defined by *attrdict*. This function is useful for taking a pickled
- :class:`LogRecord` attribute dictionary, sent over a socket, and reconstituting
- it as a :class:`LogRecord` instance at the receiving end.
-
-
-.. function:: basicConfig(**kwargs)
-
- Does basic configuration for the logging system by creating a
- :class:`StreamHandler` with a default :class:`Formatter` and adding it to the
- root logger. The functions :func:`debug`, :func:`info`, :func:`warning`,
- :func:`error` and :func:`critical` will call :func:`basicConfig` automatically
- if no handlers are defined for the root logger.
-
- This function does nothing if the root logger already has handlers
- configured for it.
-
- PLEASE NOTE: This function should be called from the main thread
- before other threads are started. In versions of Python prior to
- 2.7.1 and 3.2, if this function is called from multiple threads,
- it is possible (in rare circumstances) that a handler will be added
- to the root logger more than once, leading to unexpected results
- such as messages being duplicated in the log.
-
- The following keyword arguments are supported.
-
- +--------------+---------------------------------------------+
- | Format | Description |
- +==============+=============================================+
- | ``filename`` | Specifies that a FileHandler be created, |
- | | using the specified filename, rather than a |
- | | StreamHandler. |
- +--------------+---------------------------------------------+
- | ``filemode`` | Specifies the mode to open the file, if |
- | | filename is specified (if filemode is |
- | | unspecified, it defaults to 'a'). |
- +--------------+---------------------------------------------+
- | ``format`` | Use the specified format string for the |
- | | handler. |
- +--------------+---------------------------------------------+
- | ``datefmt`` | Use the specified date/time format. |
- +--------------+---------------------------------------------+
- | ``style`` | If ``format`` is specified, use this style |
- | | for the format string. One of '%', '{' or |
- | | '$' for %-formatting, :meth:`str.format` or |
- | | :class:`string.Template` respectively, and |
- | | defaulting to '%' if not specified. |
- +--------------+---------------------------------------------+
- | ``level`` | Set the root logger level to the specified |
- | | level. |
- +--------------+---------------------------------------------+
- | ``stream`` | Use the specified stream to initialize the |
- | | StreamHandler. Note that this argument is |
- | | incompatible with 'filename' - if both are |
- | | present, 'stream' is ignored. |
- +--------------+---------------------------------------------+
-
- .. versionchanged:: 3.2
- The ``style`` argument was added.
-
-
-.. function:: shutdown()
-
- Informs the logging system to perform an orderly shutdown by flushing and
- closing all handlers. This should be called at application exit and no
- further use of the logging system should be made after this call.
-
-
-.. function:: setLoggerClass(klass)
-
- Tells the logging system to use the class *klass* when instantiating a logger.
- The class should define :meth:`__init__` such that only a name argument is
- required, and the :meth:`__init__` should call :meth:`Logger.__init__`. This
- function is typically called before any loggers are instantiated by applications
- which need to use custom logger behavior.
-
-
-.. function:: setLogRecordFactory(factory)
-
- Set a callable which is used to create a :class:`LogRecord`.
-
- :param factory: The factory callable to be used to instantiate a log record.
-
- .. versionadded:: 3.2
- This function has been provided, along with :func:`getLogRecordFactory`, to
- allow developers more control over how the :class:`LogRecord` representing
- a logging event is constructed.
-
- The factory has the following signature:
-
- ``factory(name, level, fn, lno, msg, args, exc_info, func=None, sinfo=None, **kwargs)``
-
- :name: The logger name.
- :level: The logging level (numeric).
- :fn: The full pathname of the file where the logging call was made.
- :lno: The line number in the file where the logging call was made.
- :msg: The logging message.
- :args: The arguments for the logging message.
- :exc_info: An exception tuple, or None.
- :func: The name of the function or method which invoked the logging
- call.
- :sinfo: A stack traceback such as is provided by
- :func:`traceback.print_stack`, showing the call hierarchy.
- :kwargs: Additional keyword arguments.
-
-
-.. seealso::
-
- :pep:`282` - A Logging System
- The proposal which described this feature for inclusion in the Python standard
- library.
-
- `Original Python logging package <http://www.red-dove.com/python_logging.html>`_
- This is the original source for the :mod:`logging` package. The version of the
- package available from this site is suitable for use with Python 1.5.2, 2.1.x
- and 2.2.x, which do not include the :mod:`logging` package in the standard
- library.
.. _logger:
@@ -1486,945 +273,6 @@ instantiated directly, but always through the module-level function
.. versionadded:: 3.2
-.. _basic-example:
-
-Basic example
--------------
-
-The :mod:`logging` package provides a lot of flexibility, and its configuration
-can appear daunting. This section demonstrates that simple use of the logging
-package is possible.
-
-The simplest example shows logging to the console::
-
- import logging
-
- logging.debug('A debug message')
- logging.info('Some information')
- logging.warning('A shot across the bows')
-
-If you run the above script, you'll see this::
-
- WARNING:root:A shot across the bows
-
-Because no particular logger was specified, the system used the root logger. The
-debug and info messages didn't appear because by default, the root logger is
-configured to only handle messages with a severity of WARNING or above. The
-message format is also a configuration default, as is the output destination of
-the messages - ``sys.stderr``. The severity level, the message format and
-destination can be easily changed, as shown in the example below::
-
- import logging
-
- logging.basicConfig(level=logging.DEBUG,
- format='%(asctime)s %(levelname)s %(message)s',
- filename='myapp.log',
- filemode='w')
- logging.debug('A debug message')
- logging.info('Some information')
- logging.warning('A shot across the bows')
-
-The :meth:`basicConfig` method is used to change the configuration defaults,
-which results in output (written to ``myapp.log``) which should look
-something like the following::
-
- 2004-07-02 13:00:08,743 DEBUG A debug message
- 2004-07-02 13:00:08,743 INFO Some information
- 2004-07-02 13:00:08,743 WARNING A shot across the bows
-
-This time, all messages with a severity of DEBUG or above were handled, and the
-format of the messages was also changed, and output went to the specified file
-rather than the console.
-
-.. XXX logging should probably be updated for new string formatting!
-
-Formatting uses the old Python string formatting - see section
-:ref:`old-string-formatting`. The format string takes the following common
-specifiers. For a complete list of specifiers, consult the :class:`Formatter`
-documentation.
-
-+-------------------+-----------------------------------------------+
-| Format | Description |
-+===================+===============================================+
-| ``%(name)s`` | Name of the logger (logging channel). |
-+-------------------+-----------------------------------------------+
-| ``%(levelname)s`` | Text logging level for the message |
-| | (``'DEBUG'``, ``'INFO'``, ``'WARNING'``, |
-| | ``'ERROR'``, ``'CRITICAL'``). |
-+-------------------+-----------------------------------------------+
-| ``%(asctime)s`` | Human-readable time when the |
-| | :class:`LogRecord` was created. By default |
-| | this is of the form '2003-07-08 16:49:45,896' |
-| | (the numbers after the comma are millisecond |
-| | portion of the time). |
-+-------------------+-----------------------------------------------+
-| ``%(message)s`` | The logged message. |
-+-------------------+-----------------------------------------------+
-
-To change the date/time format, you can pass an additional keyword parameter,
-*datefmt*, as in the following::
-
- import logging
-
- logging.basicConfig(level=logging.DEBUG,
- format='%(asctime)s %(levelname)-8s %(message)s',
- datefmt='%a, %d %b %Y %H:%M:%S',
- filename='/temp/myapp.log',
- filemode='w')
- logging.debug('A debug message')
- logging.info('Some information')
- logging.warning('A shot across the bows')
-
-which would result in output like ::
-
- Fri, 02 Jul 2004 13:06:18 DEBUG A debug message
- Fri, 02 Jul 2004 13:06:18 INFO Some information
- Fri, 02 Jul 2004 13:06:18 WARNING A shot across the bows
-
-The date format string follows the requirements of :func:`strftime` - see the
-documentation for the :mod:`time` module.
-
-If, instead of sending logging output to the console or a file, you'd rather use
-a file-like object which you have created separately, you can pass it to
-:func:`basicConfig` using the *stream* keyword argument. Note that if both
-*stream* and *filename* keyword arguments are passed, the *stream* argument is
-ignored.
-
-Of course, you can put variable information in your output. To do this, simply
-have the message be a format string and pass in additional arguments containing
-the variable information, as in the following example::
-
- import logging
-
- logging.basicConfig(level=logging.DEBUG,
- format='%(asctime)s %(levelname)-8s %(message)s',
- datefmt='%a, %d %b %Y %H:%M:%S',
- filename='/temp/myapp.log',
- filemode='w')
- logging.error('Pack my box with %d dozen %s', 5, 'liquor jugs')
-
-which would result in ::
-
- Wed, 21 Jul 2004 15:35:16 ERROR Pack my box with 5 dozen liquor jugs
-
-
-Using file rotation
-^^^^^^^^^^^^^^^^^^^
-
-.. sectionauthor:: Doug Hellmann, Vinay Sajip (changes)
-.. (see <http://blog.doughellmann.com/2007/05/pymotw-logging.html>)
-
-Sometimes you want to let a log file grow to a certain size, then open a new
-file and log to that. You may want to keep a certain number of these files, and
-when that many files have been created, rotate the files so that the number of
-files and the size of the files both remin bounded. For this usage pattern, the
-logging package provides a :class:`RotatingFileHandler`::
-
- import glob
- import logging
- import logging.handlers
-
- LOG_FILENAME = 'logging_rotatingfile_example.out'
-
- # Set up a specific logger with our desired output level
- my_logger = logging.getLogger('MyLogger')
- my_logger.setLevel(logging.DEBUG)
-
- # Add the log message handler to the logger
- handler = logging.handlers.RotatingFileHandler(
- LOG_FILENAME, maxBytes=20, backupCount=5)
-
- my_logger.addHandler(handler)
-
- # Log some messages
- for i in range(20):
- my_logger.debug('i = %d' % i)
-
- # See what files are created
- logfiles = glob.glob('%s*' % LOG_FILENAME)
-
- for filename in logfiles:
- print(filename)
-
-The result should be 6 separate files, each with part of the log history for the
-application::
-
- logging_rotatingfile_example.out
- logging_rotatingfile_example.out.1
- logging_rotatingfile_example.out.2
- logging_rotatingfile_example.out.3
- logging_rotatingfile_example.out.4
- logging_rotatingfile_example.out.5
-
-The most current file is always :file:`logging_rotatingfile_example.out`,
-and each time it reaches the size limit it is renamed with the suffix
-``.1``. Each of the existing backup files is renamed to increment the suffix
-(``.1`` becomes ``.2``, etc.) and the ``.6`` file is erased.
-
-Obviously this example sets the log length much much too small as an extreme
-example. You would want to set *maxBytes* to an appropriate value.
-
-
-The logger, handler, and log message call each specify a level. The log message
-is only emitted if the handler and logger are configured to emit messages of
-that level or lower. For example, if a message is ``CRITICAL``, and the logger
-is set to ``ERROR``, the message is emitted. If a message is a ``WARNING``, and
-the logger is set to produce only ``ERROR``\s, the message is not emitted::
-
- import logging
- import sys
-
- LEVELS = {'debug': logging.DEBUG,
- 'info': logging.INFO,
- 'warning': logging.WARNING,
- 'error': logging.ERROR,
- 'critical': logging.CRITICAL}
-
- if len(sys.argv) > 1:
- level_name = sys.argv[1]
- level = LEVELS.get(level_name, logging.NOTSET)
- logging.basicConfig(level=level)
-
- logging.debug('This is a debug message')
- logging.info('This is an info message')
- logging.warning('This is a warning message')
- logging.error('This is an error message')
- logging.critical('This is a critical error message')
-
-Run the script with an argument like 'debug' or 'warning' to see which messages
-show up at different levels::
-
- $ python logging_level_example.py debug
- DEBUG:root:This is a debug message
- INFO:root:This is an info message
- WARNING:root:This is a warning message
- ERROR:root:This is an error message
- CRITICAL:root:This is a critical error message
-
- $ python logging_level_example.py info
- INFO:root:This is an info message
- WARNING:root:This is a warning message
- ERROR:root:This is an error message
- CRITICAL:root:This is a critical error message
-
-You will notice that these log messages all have ``root`` embedded in them. The
-logging module supports a hierarchy of loggers with different names. An easy
-way to tell where a specific log message comes from is to use a separate logger
-object for each of your modules. Each new logger 'inherits' the configuration
-of its parent, and log messages sent to a logger include the name of that
-logger. Optionally, each logger can be configured differently, so that messages
-from different modules are handled in different ways. Let's look at a simple
-example of how to log from different modules so it is easy to trace the source
-of the message::
-
- import logging
-
- logging.basicConfig(level=logging.WARNING)
-
- logger1 = logging.getLogger('package1.module1')
- logger2 = logging.getLogger('package2.module2')
-
- logger1.warning('This message comes from one module')
- logger2.warning('And this message comes from another module')
-
-And the output::
-
- $ python logging_modules_example.py
- WARNING:package1.module1:This message comes from one module
- WARNING:package2.module2:And this message comes from another module
-
-There are many more options for configuring logging, including different log
-message formatting options, having messages delivered to multiple destinations,
-and changing the configuration of a long-running application on the fly using a
-socket interface. All of these options are covered in depth in the library
-module documentation.
-
-
-.. _multiple-destinations:
-
-Logging to multiple destinations
---------------------------------
-
-Let's say you want to log to console and file with different message formats and
-in differing circumstances. Say you want to log messages with levels of DEBUG
-and higher to file, and those messages at level INFO and higher to the console.
-Let's also assume that the file should contain timestamps, but the console
-messages should not. Here's how you can achieve this::
-
- import logging
-
- # set up logging to file - see previous section for more details
- logging.basicConfig(level=logging.DEBUG,
- format='%(asctime)s %(name)-12s %(levelname)-8s %(message)s',
- datefmt='%m-%d %H:%M',
- filename='/temp/myapp.log',
- filemode='w')
- # define a Handler which writes INFO messages or higher to the sys.stderr
- console = logging.StreamHandler()
- console.setLevel(logging.INFO)
- # set a format which is simpler for console use
- formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s')
- # tell the handler to use this format
- console.setFormatter(formatter)
- # add the handler to the root logger
- logging.getLogger('').addHandler(console)
-
- # Now, we can log to the root logger, or any other logger. First the root...
- logging.info('Jackdaws love my big sphinx of quartz.')
-
- # Now, define a couple of other loggers which might represent areas in your
- # application:
-
- logger1 = logging.getLogger('myapp.area1')
- logger2 = logging.getLogger('myapp.area2')
-
- logger1.debug('Quick zephyrs blow, vexing daft Jim.')
- logger1.info('How quickly daft jumping zebras vex.')
- logger2.warning('Jail zesty vixen who grabbed pay from quack.')
- logger2.error('The five boxing wizards jump quickly.')
-
-When you run this, on the console you will see ::
-
- root : INFO Jackdaws love my big sphinx of quartz.
- myapp.area1 : INFO How quickly daft jumping zebras vex.
- myapp.area2 : WARNING Jail zesty vixen who grabbed pay from quack.
- myapp.area2 : ERROR The five boxing wizards jump quickly.
-
-and in the file you will see something like ::
-
- 10-22 22:19 root INFO Jackdaws love my big sphinx of quartz.
- 10-22 22:19 myapp.area1 DEBUG Quick zephyrs blow, vexing daft Jim.
- 10-22 22:19 myapp.area1 INFO How quickly daft jumping zebras vex.
- 10-22 22:19 myapp.area2 WARNING Jail zesty vixen who grabbed pay from quack.
- 10-22 22:19 myapp.area2 ERROR The five boxing wizards jump quickly.
-
-As you can see, the DEBUG message only shows up in the file. The other messages
-are sent to both destinations.
-
-This example uses console and file handlers, but you can use any number and
-combination of handlers you choose.
-
-.. _logging-exceptions:
-
-Exceptions raised during logging
---------------------------------
-
-The logging package is designed to swallow exceptions which occur while logging
-in production. This is so that errors which occur while handling logging events
-- such as logging misconfiguration, network or other similar errors - do not
-cause the application using logging to terminate prematurely.
-
-:class:`SystemExit` and :class:`KeyboardInterrupt` exceptions are never
-swallowed. Other exceptions which occur during the :meth:`emit` method of a
-:class:`Handler` subclass are passed to its :meth:`handleError` method.
-
-The default implementation of :meth:`handleError` in :class:`Handler` checks
-to see if a module-level variable, :data:`raiseExceptions`, is set. If set, a
-traceback is printed to :data:`sys.stderr`. If not set, the exception is swallowed.
-
-**Note:** The default value of :data:`raiseExceptions` is ``True``. This is because
-during development, you typically want to be notified of any exceptions that
-occur. It's advised that you set :data:`raiseExceptions` to ``False`` for production
-usage.
-
-.. _context-info:
-
-Adding contextual information to your logging output
-----------------------------------------------------
-
-Sometimes you want logging output to contain contextual information in
-addition to the parameters passed to the logging call. For example, in a
-networked application, it may be desirable to log client-specific information
-in the log (e.g. remote client's username, or IP address). Although you could
-use the *extra* parameter to achieve this, it's not always convenient to pass
-the information in this way. While it might be tempting to create
-:class:`Logger` instances on a per-connection basis, this is not a good idea
-because these instances are not garbage collected. While this is not a problem
-in practice, when the number of :class:`Logger` instances is dependent on the
-level of granularity you want to use in logging an application, it could
-be hard to manage if the number of :class:`Logger` instances becomes
-effectively unbounded.
-
-
-Using LoggerAdapters to impart contextual information
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-An easy way in which you can pass contextual information to be output along
-with logging event information is to use the :class:`LoggerAdapter` class.
-This class is designed to look like a :class:`Logger`, so that you can call
-:meth:`debug`, :meth:`info`, :meth:`warning`, :meth:`error`,
-:meth:`exception`, :meth:`critical` and :meth:`log`. These methods have the
-same signatures as their counterparts in :class:`Logger`, so you can use the
-two types of instances interchangeably.
-
-When you create an instance of :class:`LoggerAdapter`, you pass it a
-:class:`Logger` instance and a dict-like object which contains your contextual
-information. When you call one of the logging methods on an instance of
-:class:`LoggerAdapter`, it delegates the call to the underlying instance of
-:class:`Logger` passed to its constructor, and arranges to pass the contextual
-information in the delegated call. Here's a snippet from the code of
-:class:`LoggerAdapter`::
-
- def debug(self, msg, *args, **kwargs):
- """
- Delegate a debug call to the underlying logger, after adding
- contextual information from this adapter instance.
- """
- msg, kwargs = self.process(msg, kwargs)
- self.logger.debug(msg, *args, **kwargs)
-
-The :meth:`process` method of :class:`LoggerAdapter` is where the contextual
-information is added to the logging output. It's passed the message and
-keyword arguments of the logging call, and it passes back (potentially)
-modified versions of these to use in the call to the underlying logger. The
-default implementation of this method leaves the message alone, but inserts
-an 'extra' key in the keyword argument whose value is the dict-like object
-passed to the constructor. Of course, if you had passed an 'extra' keyword
-argument in the call to the adapter, it will be silently overwritten.
-
-The advantage of using 'extra' is that the values in the dict-like object are
-merged into the :class:`LogRecord` instance's __dict__, allowing you to use
-customized strings with your :class:`Formatter` instances which know about
-the keys of the dict-like object. If you need a different method, e.g. if you
-want to prepend or append the contextual information to the message string,
-you just need to subclass :class:`LoggerAdapter` and override :meth:`process`
-to do what you need. Here's an example script which uses this class, which
-also illustrates what dict-like behaviour is needed from an arbitrary
-'dict-like' object for use in the constructor::
-
- import logging
-
- class ConnInfo:
- """
- An example class which shows how an arbitrary class can be used as
- the 'extra' context information repository passed to a LoggerAdapter.
- """
-
- def __getitem__(self, name):
- """
- To allow this instance to look like a dict.
- """
- from random import choice
- if name == 'ip':
- result = choice(['127.0.0.1', '192.168.0.1'])
- elif name == 'user':
- result = choice(['jim', 'fred', 'sheila'])
- else:
- result = self.__dict__.get(name, '?')
- return result
-
- def __iter__(self):
- """
- To allow iteration over keys, which will be merged into
- the LogRecord dict before formatting and output.
- """
- keys = ['ip', 'user']
- keys.extend(self.__dict__.keys())
- return keys.__iter__()
-
- if __name__ == '__main__':
- from random import choice
- levels = (logging.DEBUG, logging.INFO, logging.WARNING, logging.ERROR, logging.CRITICAL)
- a1 = logging.LoggerAdapter(logging.getLogger('a.b.c'),
- { 'ip' : '123.231.231.123', 'user' : 'sheila' })
- logging.basicConfig(level=logging.DEBUG,
- format='%(asctime)-15s %(name)-5s %(levelname)-8s IP: %(ip)-15s User: %(user)-8s %(message)s')
- a1.debug('A debug message')
- a1.info('An info message with %s', 'some parameters')
- a2 = logging.LoggerAdapter(logging.getLogger('d.e.f'), ConnInfo())
- for x in range(10):
- lvl = choice(levels)
- lvlname = logging.getLevelName(lvl)
- a2.log(lvl, 'A message at %s level with %d %s', lvlname, 2, 'parameters')
-
-When this script is run, the output should look something like this::
-
- 2008-01-18 14:49:54,023 a.b.c DEBUG IP: 123.231.231.123 User: sheila A debug message
- 2008-01-18 14:49:54,023 a.b.c INFO IP: 123.231.231.123 User: sheila An info message with some parameters
- 2008-01-18 14:49:54,023 d.e.f CRITICAL IP: 192.168.0.1 User: jim A message at CRITICAL level with 2 parameters
- 2008-01-18 14:49:54,033 d.e.f INFO IP: 192.168.0.1 User: jim A message at INFO level with 2 parameters
- 2008-01-18 14:49:54,033 d.e.f WARNING IP: 192.168.0.1 User: sheila A message at WARNING level with 2 parameters
- 2008-01-18 14:49:54,033 d.e.f ERROR IP: 127.0.0.1 User: fred A message at ERROR level with 2 parameters
- 2008-01-18 14:49:54,033 d.e.f ERROR IP: 127.0.0.1 User: sheila A message at ERROR level with 2 parameters
- 2008-01-18 14:49:54,033 d.e.f WARNING IP: 192.168.0.1 User: sheila A message at WARNING level with 2 parameters
- 2008-01-18 14:49:54,033 d.e.f WARNING IP: 192.168.0.1 User: jim A message at WARNING level with 2 parameters
- 2008-01-18 14:49:54,033 d.e.f INFO IP: 192.168.0.1 User: fred A message at INFO level with 2 parameters
- 2008-01-18 14:49:54,033 d.e.f WARNING IP: 192.168.0.1 User: sheila A message at WARNING level with 2 parameters
- 2008-01-18 14:49:54,033 d.e.f WARNING IP: 127.0.0.1 User: jim A message at WARNING level with 2 parameters
-
-
-.. _filters-contextual:
-
-Using Filters to impart contextual information
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-You can also add contextual information to log output using a user-defined
-:class:`Filter`. ``Filter`` instances are allowed to modify the ``LogRecords``
-passed to them, including adding additional attributes which can then be output
-using a suitable format string, or if needed a custom :class:`Formatter`.
-
-For example in a web application, the request being processed (or at least,
-the interesting parts of it) can be stored in a threadlocal
-(:class:`threading.local`) variable, and then accessed from a ``Filter`` to
-add, say, information from the request - say, the remote IP address and remote
-user's username - to the ``LogRecord``, using the attribute names 'ip' and
-'user' as in the ``LoggerAdapter`` example above. In that case, the same format
-string can be used to get similar output to that shown above. Here's an example
-script::
-
- import logging
- from random import choice
-
- class ContextFilter(logging.Filter):
- """
- This is a filter which injects contextual information into the log.
-
- Rather than use actual contextual information, we just use random
- data in this demo.
- """
-
- USERS = ['jim', 'fred', 'sheila']
- IPS = ['123.231.231.123', '127.0.0.1', '192.168.0.1']
-
- def filter(self, record):
-
- record.ip = choice(ContextFilter.IPS)
- record.user = choice(ContextFilter.USERS)
- return True
-
- if __name__ == '__main__':
- levels = (logging.DEBUG, logging.INFO, logging.WARNING, logging.ERROR, logging.CRITICAL)
- a1 = logging.LoggerAdapter(logging.getLogger('a.b.c'),
- { 'ip' : '123.231.231.123', 'user' : 'sheila' })
- logging.basicConfig(level=logging.DEBUG,
- format='%(asctime)-15s %(name)-5s %(levelname)-8s IP: %(ip)-15s User: %(user)-8s %(message)s')
- a1 = logging.getLogger('a.b.c')
- a2 = logging.getLogger('d.e.f')
-
- f = ContextFilter()
- a1.addFilter(f)
- a2.addFilter(f)
- a1.debug('A debug message')
- a1.info('An info message with %s', 'some parameters')
- for x in range(10):
- lvl = choice(levels)
- lvlname = logging.getLevelName(lvl)
- a2.log(lvl, 'A message at %s level with %d %s', lvlname, 2, 'parameters')
-
-which, when run, produces something like::
-
- 2010-09-06 22:38:15,292 a.b.c DEBUG IP: 123.231.231.123 User: fred A debug message
- 2010-09-06 22:38:15,300 a.b.c INFO IP: 192.168.0.1 User: sheila An info message with some parameters
- 2010-09-06 22:38:15,300 d.e.f CRITICAL IP: 127.0.0.1 User: sheila A message at CRITICAL level with 2 parameters
- 2010-09-06 22:38:15,300 d.e.f ERROR IP: 127.0.0.1 User: jim A message at ERROR level with 2 parameters
- 2010-09-06 22:38:15,300 d.e.f DEBUG IP: 127.0.0.1 User: sheila A message at DEBUG level with 2 parameters
- 2010-09-06 22:38:15,300 d.e.f ERROR IP: 123.231.231.123 User: fred A message at ERROR level with 2 parameters
- 2010-09-06 22:38:15,300 d.e.f CRITICAL IP: 192.168.0.1 User: jim A message at CRITICAL level with 2 parameters
- 2010-09-06 22:38:15,300 d.e.f CRITICAL IP: 127.0.0.1 User: sheila A message at CRITICAL level with 2 parameters
- 2010-09-06 22:38:15,300 d.e.f DEBUG IP: 192.168.0.1 User: jim A message at DEBUG level with 2 parameters
- 2010-09-06 22:38:15,301 d.e.f ERROR IP: 127.0.0.1 User: sheila A message at ERROR level with 2 parameters
- 2010-09-06 22:38:15,301 d.e.f DEBUG IP: 123.231.231.123 User: fred A message at DEBUG level with 2 parameters
- 2010-09-06 22:38:15,301 d.e.f INFO IP: 123.231.231.123 User: fred A message at INFO level with 2 parameters
-
-
-.. _multiple-processes:
-
-Logging to a single file from multiple processes
-------------------------------------------------
-
-Although logging is thread-safe, and logging to a single file from multiple
-threads in a single process *is* supported, logging to a single file from
-*multiple processes* is *not* supported, because there is no standard way to
-serialize access to a single file across multiple processes in Python. If you
-need to log to a single file from multiple processes, one way of doing this is
-to have all the processes log to a :class:`SocketHandler`, and have a separate
-process which implements a socket server which reads from the socket and logs
-to file. (If you prefer, you can dedicate one thread in one of the existing
-processes to perform this function.) The following section documents this
-approach in more detail and includes a working socket receiver which can be
-used as a starting point for you to adapt in your own applications.
-
-If you are using a recent version of Python which includes the
-:mod:`multiprocessing` module, you could write your own handler which uses the
-:class:`Lock` class from this module to serialize access to the file from
-your processes. The existing :class:`FileHandler` and subclasses do not make
-use of :mod:`multiprocessing` at present, though they may do so in the future.
-Note that at present, the :mod:`multiprocessing` module does not provide
-working lock functionality on all platforms (see
-http://bugs.python.org/issue3770).
-
-.. currentmodule:: logging.handlers
-
-Alternatively, you can use a ``Queue`` and a :class:`QueueHandler` to send
-all logging events to one of the processes in your multi-process application.
-The following example script demonstrates how you can do this; in the example
-a separate listener process listens for events sent by other processes and logs
-them according to its own logging configuration. Although the example only
-demonstrates one way of doing it (for example, you may want to use a listener
-thread rather than a separate listener process - the implementation would be
-analogous) it does allow for completely different logging configurations for
-the listener and the other processes in your application, and can be used as
-the basis for code meeting your own specific requirements::
-
- # You'll need these imports in your own code
- import logging
- import logging.handlers
- import multiprocessing
-
- # Next two import lines for this demo only
- from random import choice, random
- import time
-
- #
- # Because you'll want to define the logging configurations for listener and workers, the
- # listener and worker process functions take a configurer parameter which is a callable
- # for configuring logging for that process. These functions are also passed the queue,
- # which they use for communication.
- #
- # In practice, you can configure the listener however you want, but note that in this
- # simple example, the listener does not apply level or filter logic to received records.
- # In practice, you would probably want to do ths logic in the worker processes, to avoid
- # sending events which would be filtered out between processes.
- #
- # The size of the rotated files is made small so you can see the results easily.
- def listener_configurer():
- root = logging.getLogger()
- h = logging.handlers.RotatingFileHandler('/tmp/mptest.log', 'a', 300, 10)
- f = logging.Formatter('%(asctime)s %(processName)-10s %(name)s %(levelname)-8s %(message)s')
- h.setFormatter(f)
- root.addHandler(h)
-
- # This is the listener process top-level loop: wait for logging events
- # (LogRecords)on the queue and handle them, quit when you get a None for a
- # LogRecord.
- def listener_process(queue, configurer):
- configurer()
- while True:
- try:
- record = queue.get()
- if record is None: # We send this as a sentinel to tell the listener to quit.
- break
- logger = logging.getLogger(record.name)
- logger.handle(record) # No level or filter logic applied - just do it!
- except (KeyboardInterrupt, SystemExit):
- raise
- except:
- import sys, traceback
- print >> sys.stderr, 'Whoops! Problem:'
- traceback.print_exc(file=sys.stderr)
-
- # Arrays used for random selections in this demo
-
- LEVELS = [logging.DEBUG, logging.INFO, logging.WARNING,
- logging.ERROR, logging.CRITICAL]
-
- LOGGERS = ['a.b.c', 'd.e.f']
-
- MESSAGES = [
- 'Random message #1',
- 'Random message #2',
- 'Random message #3',
- ]
-
- # The worker configuration is done at the start of the worker process run.
- # Note that on Windows you can't rely on fork semantics, so each process
- # will run the logging configuration code when it starts.
- def worker_configurer(queue):
- h = logging.handlers.QueueHandler(queue) # Just the one handler needed
- root = logging.getLogger()
- root.addHandler(h)
- root.setLevel(logging.DEBUG) # send all messages, for demo; no other level or filter logic applied.
-
- # This is the worker process top-level loop, which just logs ten events with
- # random intervening delays before terminating.
- # The print messages are just so you know it's doing something!
- def worker_process(queue, configurer):
- configurer(queue)
- name = multiprocessing.current_process().name
- print('Worker started: %s' % name)
- for i in range(10):
- time.sleep(random())
- logger = logging.getLogger(choice(LOGGERS))
- level = choice(LEVELS)
- message = choice(MESSAGES)
- logger.log(level, message)
- print('Worker finished: %s' % name)
-
- # Here's where the demo gets orchestrated. Create the queue, create and start
- # the listener, create ten workers and start them, wait for them to finish,
- # then send a None to the queue to tell the listener to finish.
- def main():
- queue = multiprocessing.Queue(-1)
- listener = multiprocessing.Process(target=listener_process,
- args=(queue, listener_configurer))
- listener.start()
- workers = []
- for i in range(10):
- worker = multiprocessing.Process(target=worker_process,
- args=(queue, worker_configurer))
- workers.append(worker)
- worker.start()
- for w in workers:
- w.join()
- queue.put_nowait(None)
- listener.join()
-
- if __name__ == '__main__':
- main()
-
-
-.. currentmodule:: logging
-
-
-.. _network-logging:
-
-Sending and receiving logging events across a network
------------------------------------------------------
-
-Let's say you want to send logging events across a network, and handle them at
-the receiving end. A simple way of doing this is attaching a
-:class:`SocketHandler` instance to the root logger at the sending end::
-
- import logging, logging.handlers
-
- rootLogger = logging.getLogger('')
- rootLogger.setLevel(logging.DEBUG)
- socketHandler = logging.handlers.SocketHandler('localhost',
- logging.handlers.DEFAULT_TCP_LOGGING_PORT)
- # don't bother with a formatter, since a socket handler sends the event as
- # an unformatted pickle
- rootLogger.addHandler(socketHandler)
-
- # Now, we can log to the root logger, or any other logger. First the root...
- logging.info('Jackdaws love my big sphinx of quartz.')
-
- # Now, define a couple of other loggers which might represent areas in your
- # application:
-
- logger1 = logging.getLogger('myapp.area1')
- logger2 = logging.getLogger('myapp.area2')
-
- logger1.debug('Quick zephyrs blow, vexing daft Jim.')
- logger1.info('How quickly daft jumping zebras vex.')
- logger2.warning('Jail zesty vixen who grabbed pay from quack.')
- logger2.error('The five boxing wizards jump quickly.')
-
-At the receiving end, you can set up a receiver using the :mod:`socketserver`
-module. Here is a basic working example::
-
- import pickle
- import logging
- import logging.handlers
- import socketserver
- import struct
-
-
- class LogRecordStreamHandler(socketserver.StreamRequestHandler):
- """Handler for a streaming logging request.
-
- This basically logs the record using whatever logging policy is
- configured locally.
- """
-
- def handle(self):
- """
- Handle multiple requests - each expected to be a 4-byte length,
- followed by the LogRecord in pickle format. Logs the record
- according to whatever policy is configured locally.
- """
- while True:
- chunk = self.connection.recv(4)
- if len(chunk) < 4:
- break
- slen = struct.unpack('>L', chunk)[0]
- chunk = self.connection.recv(slen)
- while len(chunk) < slen:
- chunk = chunk + self.connection.recv(slen - len(chunk))
- obj = self.unPickle(chunk)
- record = logging.makeLogRecord(obj)
- self.handleLogRecord(record)
-
- def unPickle(self, data):
- return pickle.loads(data)
-
- def handleLogRecord(self, record):
- # if a name is specified, we use the named logger rather than the one
- # implied by the record.
- if self.server.logname is not None:
- name = self.server.logname
- else:
- name = record.name
- logger = logging.getLogger(name)
- # N.B. EVERY record gets logged. This is because Logger.handle
- # is normally called AFTER logger-level filtering. If you want
- # to do filtering, do it at the client end to save wasting
- # cycles and network bandwidth!
- logger.handle(record)
-
- class LogRecordSocketReceiver(socketserver.ThreadingTCPServer):
- """
- Simple TCP socket-based logging receiver suitable for testing.
- """
-
- allow_reuse_address = 1
-
- def __init__(self, host='localhost',
- port=logging.handlers.DEFAULT_TCP_LOGGING_PORT,
- handler=LogRecordStreamHandler):
- socketserver.ThreadingTCPServer.__init__(self, (host, port), handler)
- self.abort = 0
- self.timeout = 1
- self.logname = None
-
- def serve_until_stopped(self):
- import select
- abort = 0
- while not abort:
- rd, wr, ex = select.select([self.socket.fileno()],
- [], [],
- self.timeout)
- if rd:
- self.handle_request()
- abort = self.abort
-
- def main():
- logging.basicConfig(
- format='%(relativeCreated)5d %(name)-15s %(levelname)-8s %(message)s')
- tcpserver = LogRecordSocketReceiver()
- print('About to start TCP server...')
- tcpserver.serve_until_stopped()
-
- if __name__ == '__main__':
- main()
-
-First run the server, and then the client. On the client side, nothing is
-printed on the console; on the server side, you should see something like::
-
- About to start TCP server...
- 59 root INFO Jackdaws love my big sphinx of quartz.
- 59 myapp.area1 DEBUG Quick zephyrs blow, vexing daft Jim.
- 69 myapp.area1 INFO How quickly daft jumping zebras vex.
- 69 myapp.area2 WARNING Jail zesty vixen who grabbed pay from quack.
- 69 myapp.area2 ERROR The five boxing wizards jump quickly.
-
-Note that there are some security issues with pickle in some scenarios. If
-these affect you, you can use an alternative serialization scheme by overriding
-the :meth:`makePickle` method and implementing your alternative there, as
-well as adapting the above script to use your alternative serialization.
-
-.. _arbitrary-object-messages:
-
-Using arbitrary objects as messages
------------------------------------
-
-In the preceding sections and examples, it has been assumed that the message
-passed when logging the event is a string. However, this is not the only
-possibility. You can pass an arbitrary object as a message, and its
-:meth:`__str__` method will be called when the logging system needs to convert
-it to a string representation. In fact, if you want to, you can avoid
-computing a string representation altogether - for example, the
-:class:`SocketHandler` emits an event by pickling it and sending it over the
-wire.
-
-Dealing with handlers that block
---------------------------------
-
-.. currentmodule:: logging.handlers
-
-Sometimes you have to get your logging handlers to do their work without
-blocking the thread you’re logging from. This is common in Web applications,
-though of course it also occurs in other scenarios.
-
-A common culprit which demonstrates sluggish behaviour is the
-:class:`SMTPHandler`: sending emails can take a long time, for a
-number of reasons outside the developer’s control (for example, a poorly
-performing mail or network infrastructure). But almost any network-based
-handler can block: Even a :class:`SocketHandler` operation may do a
-DNS query under the hood which is too slow (and this query can be deep in the
-socket library code, below the Python layer, and outside your control).
-
-One solution is to use a two-part approach. For the first part, attach only a
-:class:`QueueHandler` to those loggers which are accessed from
-performance-critical threads. They simply write to their queue, which can be
-sized to a large enough capacity or initialized with no upper bound to their
-size. The write to the queue will typically be accepted quickly, though you
-will probably need to catch the :ref:`queue.Full` exception as a precaution
-in your code. If you are a library developer who has performance-critical
-threads in their code, be sure to document this (together with a suggestion to
-attach only ``QueueHandlers`` to your loggers) for the benefit of other
-developers who will use your code.
-
-The second part of the solution is :class:`QueueListener`, which has been
-designed as the counterpart to :class:`QueueHandler`. A
-:class:`QueueListener` is very simple: it’s passed a queue and some handlers,
-and it fires up an internal thread which listens to its queue for LogRecords
-sent from ``QueueHandlers`` (or any other source of ``LogRecords``, for that
-matter). The ``LogRecords`` are removed from the queue and passed to the
-handlers for processing.
-
-The advantage of having a separate :class:`QueueListener` class is that you
-can use the same instance to service multiple ``QueueHandlers``. This is more
-resource-friendly than, say, having threaded versions of the existing handler
-classes, which would eat up one thread per handler for no particular benefit.
-
-An example of using these two classes follows (imports omitted)::
-
- que = queue.Queue(-1) # no limit on size
- queue_handler = QueueHandler(que)
- handler = logging.StreamHandler()
- listener = QueueListener(que, handler)
- root = logging.getLogger()
- root.addHandler(queue_handler)
- formatter = logging.Formatter('%(threadName)s: %(message)s')
- handler.setFormatter(formatter)
- listener.start()
- # The log output will display the thread which generated
- # the event (the main thread) rather than the internal
- # thread which monitors the internal queue. This is what
- # you want to happen.
- root.warning('Look out!')
- listener.stop()
-
-which, when run, will produce::
-
- MainThread: Look out!
-
-
-Optimization
-------------
-
-Formatting of message arguments is deferred until it cannot be avoided.
-However, computing the arguments passed to the logging method can also be
-expensive, and you may want to avoid doing it if the logger will just throw
-away your event. To decide what to do, you can call the :meth:`isEnabledFor`
-method which takes a level argument and returns true if the event would be
-created by the Logger for that level of call. You can write code like this::
-
- if logger.isEnabledFor(logging.DEBUG):
- logger.debug('Message with %s, %s', expensive_func1(),
- expensive_func2())
-
-so that if the logger's threshold is set above ``DEBUG``, the calls to
-:func:`expensive_func1` and :func:`expensive_func2` are never made.
-
-There are other optimizations which can be made for specific applications which
-need more precise control over what logging information is collected. Here's a
-list of things you can do to avoid processing during logging which you don't
-need:
-
-+-----------------------------------------------+----------------------------------------+
-| What you don't want to collect | How to avoid collecting it |
-+===============================================+========================================+
-| Information about where calls were made from. | Set ``logging._srcfile`` to ``None``. |
-+-----------------------------------------------+----------------------------------------+
-| Threading information. | Set ``logging.logThreads`` to ``0``. |
-+-----------------------------------------------+----------------------------------------+
-| Process information. | Set ``logging.logProcesses`` to ``0``. |
-+-----------------------------------------------+----------------------------------------+
-
-Also note that the core logging module only includes the basic handlers. If
-you don't import :mod:`logging.handlers` and :mod:`logging.config`, they won't
-take up any memory.
.. _handler:
@@ -2532,859 +380,7 @@ subclasses. However, the :meth:`__init__` method in subclasses needs to call
is intended to be implemented by subclasses and so raises a
:exc:`NotImplementedError`.
-
-.. _stream-handler:
-
-StreamHandler
-^^^^^^^^^^^^^
-
-The :class:`StreamHandler` class, located in the core :mod:`logging` package,
-sends logging output to streams such as *sys.stdout*, *sys.stderr* or any
-file-like object (or, more precisely, any object which supports :meth:`write`
-and :meth:`flush` methods).
-
-
-.. currentmodule:: logging
-
-.. class:: StreamHandler(stream=None)
-
- Returns a new instance of the :class:`StreamHandler` class. If *stream* is
- specified, the instance will use it for logging output; otherwise, *sys.stderr*
- will be used.
-
-
- .. method:: emit(record)
-
- If a formatter is specified, it is used to format the record. The record
- is then written to the stream with a trailing newline. If exception
- information is present, it is formatted using
- :func:`traceback.print_exception` and appended to the stream.
-
-
- .. method:: flush()
-
- Flushes the stream by calling its :meth:`flush` method. Note that the
- :meth:`close` method is inherited from :class:`Handler` and so does
- no output, so an explicit :meth:`flush` call may be needed at times.
-
-.. versionchanged:: 3.2
- The ``StreamHandler`` class now has a ``terminator`` attribute, default
- value ``'\n'``, which is used as the terminator when writing a formatted
- record to a stream. If you don't want this newline termination, you can
- set the handler instance's ``terminator`` attribute to the empty string.
-
-.. _file-handler:
-
-FileHandler
-^^^^^^^^^^^
-
-The :class:`FileHandler` class, located in the core :mod:`logging` package,
-sends logging output to a disk file. It inherits the output functionality from
-:class:`StreamHandler`.
-
-
-.. class:: FileHandler(filename, mode='a', encoding=None, delay=False)
-
- Returns a new instance of the :class:`FileHandler` class. The specified file is
- opened and used as the stream for logging. If *mode* is not specified,
- :const:`'a'` is used. If *encoding* is not *None*, it is used to open the file
- with that encoding. If *delay* is true, then file opening is deferred until the
- first call to :meth:`emit`. By default, the file grows indefinitely.
-
-
- .. method:: close()
-
- Closes the file.
-
-
- .. method:: emit(record)
-
- Outputs the record to the file.
-
-
-.. _null-handler:
-
-NullHandler
-^^^^^^^^^^^
-
-.. versionadded:: 3.1
-
-The :class:`NullHandler` class, located in the core :mod:`logging` package,
-does not do any formatting or output. It is essentially a 'no-op' handler
-for use by library developers.
-
-.. class:: NullHandler()
-
- Returns a new instance of the :class:`NullHandler` class.
-
- .. method:: emit(record)
-
- This method does nothing.
-
- .. method:: handle(record)
-
- This method does nothing.
-
- .. method:: createLock()
-
- This method returns ``None`` for the lock, since there is no
- underlying I/O to which access needs to be serialized.
-
-
-See :ref:`library-config` for more information on how to use
-:class:`NullHandler`.
-
-.. _watched-file-handler:
-
-WatchedFileHandler
-^^^^^^^^^^^^^^^^^^
-
-.. currentmodule:: logging.handlers
-
-The :class:`WatchedFileHandler` class, located in the :mod:`logging.handlers`
-module, is a :class:`FileHandler` which watches the file it is logging to. If
-the file changes, it is closed and reopened using the file name.
-
-A file change can happen because of usage of programs such as *newsyslog* and
-*logrotate* which perform log file rotation. This handler, intended for use
-under Unix/Linux, watches the file to see if it has changed since the last emit.
-(A file is deemed to have changed if its device or inode have changed.) If the
-file has changed, the old file stream is closed, and the file opened to get a
-new stream.
-
-This handler is not appropriate for use under Windows, because under Windows
-open log files cannot be moved or renamed - logging opens the files with
-exclusive locks - and so there is no need for such a handler. Furthermore,
-*ST_INO* is not supported under Windows; :func:`stat` always returns zero for
-this value.
-
-
-.. class:: WatchedFileHandler(filename[,mode[, encoding[, delay]]])
-
- Returns a new instance of the :class:`WatchedFileHandler` class. The specified
- file is opened and used as the stream for logging. If *mode* is not specified,
- :const:`'a'` is used. If *encoding* is not *None*, it is used to open the file
- with that encoding. If *delay* is true, then file opening is deferred until the
- first call to :meth:`emit`. By default, the file grows indefinitely.
-
-
- .. method:: emit(record)
-
- Outputs the record to the file, but first checks to see if the file has
- changed. If it has, the existing stream is flushed and closed and the
- file opened again, before outputting the record to the file.
-
-.. _rotating-file-handler:
-
-RotatingFileHandler
-^^^^^^^^^^^^^^^^^^^
-
-The :class:`RotatingFileHandler` class, located in the :mod:`logging.handlers`
-module, supports rotation of disk log files.
-
-
-.. class:: RotatingFileHandler(filename, mode='a', maxBytes=0, backupCount=0, encoding=None, delay=0)
-
- Returns a new instance of the :class:`RotatingFileHandler` class. The specified
- file is opened and used as the stream for logging. If *mode* is not specified,
- ``'a'`` is used. If *encoding* is not *None*, it is used to open the file
- with that encoding. If *delay* is true, then file opening is deferred until the
- first call to :meth:`emit`. By default, the file grows indefinitely.
-
- You can use the *maxBytes* and *backupCount* values to allow the file to
- :dfn:`rollover` at a predetermined size. When the size is about to be exceeded,
- the file is closed and a new file is silently opened for output. Rollover occurs
- whenever the current log file is nearly *maxBytes* in length; if *maxBytes* is
- zero, rollover never occurs. If *backupCount* is non-zero, the system will save
- old log files by appending the extensions '.1', '.2' etc., to the filename. For
- example, with a *backupCount* of 5 and a base file name of :file:`app.log`, you
- would get :file:`app.log`, :file:`app.log.1`, :file:`app.log.2`, up to
- :file:`app.log.5`. The file being written to is always :file:`app.log`. When
- this file is filled, it is closed and renamed to :file:`app.log.1`, and if files
- :file:`app.log.1`, :file:`app.log.2`, etc. exist, then they are renamed to
- :file:`app.log.2`, :file:`app.log.3` etc. respectively.
-
-
- .. method:: doRollover()
-
- Does a rollover, as described above.
-
-
- .. method:: emit(record)
-
- Outputs the record to the file, catering for rollover as described
- previously.
-
-.. _timed-rotating-file-handler:
-
-TimedRotatingFileHandler
-^^^^^^^^^^^^^^^^^^^^^^^^
-
-The :class:`TimedRotatingFileHandler` class, located in the
-:mod:`logging.handlers` module, supports rotation of disk log files at certain
-timed intervals.
-
-
-.. class:: TimedRotatingFileHandler(filename, when='h', interval=1, backupCount=0, encoding=None, delay=False, utc=False)
-
- Returns a new instance of the :class:`TimedRotatingFileHandler` class. The
- specified file is opened and used as the stream for logging. On rotating it also
- sets the filename suffix. Rotating happens based on the product of *when* and
- *interval*.
-
- You can use the *when* to specify the type of *interval*. The list of possible
- values is below. Note that they are not case sensitive.
-
- +----------------+-----------------------+
- | Value | Type of interval |
- +================+=======================+
- | ``'S'`` | Seconds |
- +----------------+-----------------------+
- | ``'M'`` | Minutes |
- +----------------+-----------------------+
- | ``'H'`` | Hours |
- +----------------+-----------------------+
- | ``'D'`` | Days |
- +----------------+-----------------------+
- | ``'W'`` | Week day (0=Monday) |
- +----------------+-----------------------+
- | ``'midnight'`` | Roll over at midnight |
- +----------------+-----------------------+
-
- The system will save old log files by appending extensions to the filename.
- The extensions are date-and-time based, using the strftime format
- ``%Y-%m-%d_%H-%M-%S`` or a leading portion thereof, depending on the
- rollover interval.
-
- When computing the next rollover time for the first time (when the handler
- is created), the last modification time of an existing log file, or else
- the current time, is used to compute when the next rotation will occur.
-
- If the *utc* argument is true, times in UTC will be used; otherwise
- local time is used.
-
- If *backupCount* is nonzero, at most *backupCount* files
- will be kept, and if more would be created when rollover occurs, the oldest
- one is deleted. The deletion logic uses the interval to determine which
- files to delete, so changing the interval may leave old files lying around.
-
- If *delay* is true, then file opening is deferred until the first call to
- :meth:`emit`.
-
-
- .. method:: doRollover()
-
- Does a rollover, as described above.
-
-
- .. method:: emit(record)
-
- Outputs the record to the file, catering for rollover as described above.
-
-
-.. _socket-handler:
-
-SocketHandler
-^^^^^^^^^^^^^
-
-The :class:`SocketHandler` class, located in the :mod:`logging.handlers` module,
-sends logging output to a network socket. The base class uses a TCP socket.
-
-
-.. class:: SocketHandler(host, port)
-
- Returns a new instance of the :class:`SocketHandler` class intended to
- communicate with a remote machine whose address is given by *host* and *port*.
-
-
- .. method:: close()
-
- Closes the socket.
-
-
- .. method:: emit()
-
- Pickles the record's attribute dictionary and writes it to the socket in
- binary format. If there is an error with the socket, silently drops the
- packet. If the connection was previously lost, re-establishes the
- connection. To unpickle the record at the receiving end into a
- :class:`LogRecord`, use the :func:`makeLogRecord` function.
-
-
- .. method:: handleError()
-
- Handles an error which has occurred during :meth:`emit`. The most likely
- cause is a lost connection. Closes the socket so that we can retry on the
- next event.
-
-
- .. method:: makeSocket()
-
- This is a factory method which allows subclasses to define the precise
- type of socket they want. The default implementation creates a TCP socket
- (:const:`socket.SOCK_STREAM`).
-
-
- .. method:: makePickle(record)
-
- Pickles the record's attribute dictionary in binary format with a length
- prefix, and returns it ready for transmission across the socket.
-
- Note that pickles aren't completely secure. If you are concerned about
- security, you may want to override this method to implement a more secure
- mechanism. For example, you can sign pickles using HMAC and then verify
- them on the receiving end, or alternatively you can disable unpickling of
- global objects on the receiving end.
-
- .. method:: send(packet)
-
- Send a pickled string *packet* to the socket. This function allows for
- partial sends which can happen when the network is busy.
-
-
-.. _datagram-handler:
-
-DatagramHandler
-^^^^^^^^^^^^^^^
-
-The :class:`DatagramHandler` class, located in the :mod:`logging.handlers`
-module, inherits from :class:`SocketHandler` to support sending logging messages
-over UDP sockets.
-
-
-.. class:: DatagramHandler(host, port)
-
- Returns a new instance of the :class:`DatagramHandler` class intended to
- communicate with a remote machine whose address is given by *host* and *port*.
-
-
- .. method:: emit()
-
- Pickles the record's attribute dictionary and writes it to the socket in
- binary format. If there is an error with the socket, silently drops the
- packet. To unpickle the record at the receiving end into a
- :class:`LogRecord`, use the :func:`makeLogRecord` function.
-
-
- .. method:: makeSocket()
-
- The factory method of :class:`SocketHandler` is here overridden to create
- a UDP socket (:const:`socket.SOCK_DGRAM`).
-
-
- .. method:: send(s)
-
- Send a pickled string to a socket.
-
-
-.. _syslog-handler:
-
-SysLogHandler
-^^^^^^^^^^^^^
-
-The :class:`SysLogHandler` class, located in the :mod:`logging.handlers` module,
-supports sending logging messages to a remote or local Unix syslog.
-
-
-.. class:: SysLogHandler(address=('localhost', SYSLOG_UDP_PORT), facility=LOG_USER, socktype=socket.SOCK_DGRAM)
-
- Returns a new instance of the :class:`SysLogHandler` class intended to
- communicate with a remote Unix machine whose address is given by *address* in
- the form of a ``(host, port)`` tuple. If *address* is not specified,
- ``('localhost', 514)`` is used. The address is used to open a socket. An
- alternative to providing a ``(host, port)`` tuple is providing an address as a
- string, for example '/dev/log'. In this case, a Unix domain socket is used to
- send the message to the syslog. If *facility* is not specified,
- :const:`LOG_USER` is used. The type of socket opened depends on the
- *socktype* argument, which defaults to :const:`socket.SOCK_DGRAM` and thus
- opens a UDP socket. To open a TCP socket (for use with the newer syslog
- daemons such as rsyslog), specify a value of :const:`socket.SOCK_STREAM`.
-
- Note that if your server is not listening on UDP port 514,
- :class:`SysLogHandler` may appear not to work. In that case, check what
- address you should be using for a domain socket - it's system dependent.
- For example, on Linux it's usually '/dev/log' but on OS/X it's
- '/var/run/syslog'. You'll need to check your platform and use the
- appropriate address (you may need to do this check at runtime if your
- application needs to run on several platforms). On Windows, you pretty
- much have to use the UDP option.
-
- .. versionchanged:: 3.2
- *socktype* was added.
-
-
- .. method:: close()
-
- Closes the socket to the remote host.
-
-
- .. method:: emit(record)
-
- The record is formatted, and then sent to the syslog server. If exception
- information is present, it is *not* sent to the server.
-
-
- .. method:: encodePriority(facility, priority)
-
- Encodes the facility and priority into an integer. You can pass in strings
- or integers - if strings are passed, internal mapping dictionaries are
- used to convert them to integers.
-
- The symbolic ``LOG_`` values are defined in :class:`SysLogHandler` and
- mirror the values defined in the ``sys/syslog.h`` header file.
-
- **Priorities**
-
- +--------------------------+---------------+
- | Name (string) | Symbolic value|
- +==========================+===============+
- | ``alert`` | LOG_ALERT |
- +--------------------------+---------------+
- | ``crit`` or ``critical`` | LOG_CRIT |
- +--------------------------+---------------+
- | ``debug`` | LOG_DEBUG |
- +--------------------------+---------------+
- | ``emerg`` or ``panic`` | LOG_EMERG |
- +--------------------------+---------------+
- | ``err`` or ``error`` | LOG_ERR |
- +--------------------------+---------------+
- | ``info`` | LOG_INFO |
- +--------------------------+---------------+
- | ``notice`` | LOG_NOTICE |
- +--------------------------+---------------+
- | ``warn`` or ``warning`` | LOG_WARNING |
- +--------------------------+---------------+
-
- **Facilities**
-
- +---------------+---------------+
- | Name (string) | Symbolic value|
- +===============+===============+
- | ``auth`` | LOG_AUTH |
- +---------------+---------------+
- | ``authpriv`` | LOG_AUTHPRIV |
- +---------------+---------------+
- | ``cron`` | LOG_CRON |
- +---------------+---------------+
- | ``daemon`` | LOG_DAEMON |
- +---------------+---------------+
- | ``ftp`` | LOG_FTP |
- +---------------+---------------+
- | ``kern`` | LOG_KERN |
- +---------------+---------------+
- | ``lpr`` | LOG_LPR |
- +---------------+---------------+
- | ``mail`` | LOG_MAIL |
- +---------------+---------------+
- | ``news`` | LOG_NEWS |
- +---------------+---------------+
- | ``syslog`` | LOG_SYSLOG |
- +---------------+---------------+
- | ``user`` | LOG_USER |
- +---------------+---------------+
- | ``uucp`` | LOG_UUCP |
- +---------------+---------------+
- | ``local0`` | LOG_LOCAL0 |
- +---------------+---------------+
- | ``local1`` | LOG_LOCAL1 |
- +---------------+---------------+
- | ``local2`` | LOG_LOCAL2 |
- +---------------+---------------+
- | ``local3`` | LOG_LOCAL3 |
- +---------------+---------------+
- | ``local4`` | LOG_LOCAL4 |
- +---------------+---------------+
- | ``local5`` | LOG_LOCAL5 |
- +---------------+---------------+
- | ``local6`` | LOG_LOCAL6 |
- +---------------+---------------+
- | ``local7`` | LOG_LOCAL7 |
- +---------------+---------------+
-
- .. method:: mapPriority(levelname)
-
- Maps a logging level name to a syslog priority name.
- You may need to override this if you are using custom levels, or
- if the default algorithm is not suitable for your needs. The
- default algorithm maps ``DEBUG``, ``INFO``, ``WARNING``, ``ERROR`` and
- ``CRITICAL`` to the equivalent syslog names, and all other level
- names to 'warning'.
-
-.. _nt-eventlog-handler:
-
-NTEventLogHandler
-^^^^^^^^^^^^^^^^^
-
-The :class:`NTEventLogHandler` class, located in the :mod:`logging.handlers`
-module, supports sending logging messages to a local Windows NT, Windows 2000 or
-Windows XP event log. Before you can use it, you need Mark Hammond's Win32
-extensions for Python installed.
-
-
-.. class:: NTEventLogHandler(appname, dllname=None, logtype='Application')
-
- Returns a new instance of the :class:`NTEventLogHandler` class. The *appname* is
- used to define the application name as it appears in the event log. An
- appropriate registry entry is created using this name. The *dllname* should give
- the fully qualified pathname of a .dll or .exe which contains message
- definitions to hold in the log (if not specified, ``'win32service.pyd'`` is used
- - this is installed with the Win32 extensions and contains some basic
- placeholder message definitions. Note that use of these placeholders will make
- your event logs big, as the entire message source is held in the log. If you
- want slimmer logs, you have to pass in the name of your own .dll or .exe which
- contains the message definitions you want to use in the event log). The
- *logtype* is one of ``'Application'``, ``'System'`` or ``'Security'``, and
- defaults to ``'Application'``.
-
-
- .. method:: close()
-
- At this point, you can remove the application name from the registry as a
- source of event log entries. However, if you do this, you will not be able
- to see the events as you intended in the Event Log Viewer - it needs to be
- able to access the registry to get the .dll name. The current version does
- not do this.
-
-
- .. method:: emit(record)
-
- Determines the message ID, event category and event type, and then logs
- the message in the NT event log.
-
-
- .. method:: getEventCategory(record)
-
- Returns the event category for the record. Override this if you want to
- specify your own categories. This version returns 0.
-
-
- .. method:: getEventType(record)
-
- Returns the event type for the record. Override this if you want to
- specify your own types. This version does a mapping using the handler's
- typemap attribute, which is set up in :meth:`__init__` to a dictionary
- which contains mappings for :const:`DEBUG`, :const:`INFO`,
- :const:`WARNING`, :const:`ERROR` and :const:`CRITICAL`. If you are using
- your own levels, you will either need to override this method or place a
- suitable dictionary in the handler's *typemap* attribute.
-
-
- .. method:: getMessageID(record)
-
- Returns the message ID for the record. If you are using your own messages,
- you could do this by having the *msg* passed to the logger being an ID
- rather than a format string. Then, in here, you could use a dictionary
- lookup to get the message ID. This version returns 1, which is the base
- message ID in :file:`win32service.pyd`.
-
-.. _smtp-handler:
-
-SMTPHandler
-^^^^^^^^^^^
-
-The :class:`SMTPHandler` class, located in the :mod:`logging.handlers` module,
-supports sending logging messages to an email address via SMTP.
-
-
-.. class:: SMTPHandler(mailhost, fromaddr, toaddrs, subject, credentials=None)
-
- Returns a new instance of the :class:`SMTPHandler` class. The instance is
- initialized with the from and to addresses and subject line of the email. The
- *toaddrs* should be a list of strings. To specify a non-standard SMTP port, use
- the (host, port) tuple format for the *mailhost* argument. If you use a string,
- the standard SMTP port is used. If your SMTP server requires authentication, you
- can specify a (username, password) tuple for the *credentials* argument.
-
-
- .. method:: emit(record)
-
- Formats the record and sends it to the specified addressees.
-
-
- .. method:: getSubject(record)
-
- If you want to specify a subject line which is record-dependent, override
- this method.
-
-.. _memory-handler:
-
-MemoryHandler
-^^^^^^^^^^^^^
-
-The :class:`MemoryHandler` class, located in the :mod:`logging.handlers` module,
-supports buffering of logging records in memory, periodically flushing them to a
-:dfn:`target` handler. Flushing occurs whenever the buffer is full, or when an
-event of a certain severity or greater is seen.
-
-:class:`MemoryHandler` is a subclass of the more general
-:class:`BufferingHandler`, which is an abstract class. This buffers logging
-records in memory. Whenever each record is added to the buffer, a check is made
-by calling :meth:`shouldFlush` to see if the buffer should be flushed. If it
-should, then :meth:`flush` is expected to do the needful.
-
-
-.. class:: BufferingHandler(capacity)
-
- Initializes the handler with a buffer of the specified capacity.
-
-
- .. method:: emit(record)
-
- Appends the record to the buffer. If :meth:`shouldFlush` returns true,
- calls :meth:`flush` to process the buffer.
-
-
- .. method:: flush()
-
- You can override this to implement custom flushing behavior. This version
- just zaps the buffer to empty.
-
-
- .. method:: shouldFlush(record)
-
- Returns true if the buffer is up to capacity. This method can be
- overridden to implement custom flushing strategies.
-
-
-.. class:: MemoryHandler(capacity, flushLevel=ERROR, target=None)
-
- Returns a new instance of the :class:`MemoryHandler` class. The instance is
- initialized with a buffer size of *capacity*. If *flushLevel* is not specified,
- :const:`ERROR` is used. If no *target* is specified, the target will need to be
- set using :meth:`setTarget` before this handler does anything useful.
-
-
- .. method:: close()
-
- Calls :meth:`flush`, sets the target to :const:`None` and clears the
- buffer.
-
-
- .. method:: flush()
-
- For a :class:`MemoryHandler`, flushing means just sending the buffered
- records to the target, if there is one. The buffer is also cleared when
- this happens. Override if you want different behavior.
-
-
- .. method:: setTarget(target)
-
- Sets the target handler for this handler.
-
-
- .. method:: shouldFlush(record)
-
- Checks for buffer full or a record at the *flushLevel* or higher.
-
-
-.. _http-handler:
-
-HTTPHandler
-^^^^^^^^^^^
-
-The :class:`HTTPHandler` class, located in the :mod:`logging.handlers` module,
-supports sending logging messages to a Web server, using either ``GET`` or
-``POST`` semantics.
-
-
-.. class:: HTTPHandler(host, url, method='GET', secure=False, credentials=None)
-
- Returns a new instance of the :class:`HTTPHandler` class. The *host* can be
- of the form ``host:port``, should you need to use a specific port number.
- If no *method* is specified, ``GET`` is used. If *secure* is True, an HTTPS
- connection will be used. If *credentials* is specified, it should be a
- 2-tuple consisting of userid and password, which will be placed in an HTTP
- 'Authorization' header using Basic authentication. If you specify
- credentials, you should also specify secure=True so that your userid and
- password are not passed in cleartext across the wire.
-
-
- .. method:: emit(record)
-
- Sends the record to the Web server as a percent-encoded dictionary.
-
-
-.. _queue-handler:
-
-
-QueueHandler
-^^^^^^^^^^^^
-
-.. versionadded:: 3.2
-
-The :class:`QueueHandler` class, located in the :mod:`logging.handlers` module,
-supports sending logging messages to a queue, such as those implemented in the
-:mod:`queue` or :mod:`multiprocessing` modules.
-
-Along with the :class:`QueueListener` class, :class:`QueueHandler` can be used
-to let handlers do their work on a separate thread from the one which does the
-logging. This is important in Web applications and also other service
-applications where threads servicing clients need to respond as quickly as
-possible, while any potentially slow operations (such as sending an email via
-:class:`SMTPHandler`) are done on a separate thread.
-
-.. class:: QueueHandler(queue)
-
- Returns a new instance of the :class:`QueueHandler` class. The instance is
- initialized with the queue to send messages to. The queue can be any queue-
- like object; it's used as-is by the :meth:`enqueue` method, which needs
- to know how to send messages to it.
-
-
- .. method:: emit(record)
-
- Enqueues the result of preparing the LogRecord.
-
- .. method:: prepare(record)
-
- Prepares a record for queuing. The object returned by this
- method is enqueued.
-
- The base implementation formats the record to merge the message
- and arguments, and removes unpickleable items from the record
- in-place.
-
- You might want to override this method if you want to convert
- the record to a dict or JSON string, or send a modified copy
- of the record while leaving the original intact.
-
- .. method:: enqueue(record)
-
- Enqueues the record on the queue using ``put_nowait()``; you may
- want to override this if you want to use blocking behaviour, or a
- timeout, or a customised queue implementation.
-
-
-
-.. queue-listener:
-
-QueueListener
-^^^^^^^^^^^^^
-
-.. versionadded:: 3.2
-
-The :class:`QueueListener` class, located in the :mod:`logging.handlers`
-module, supports receiving logging messages from a queue, such as those
-implemented in the :mod:`queue` or :mod:`multiprocessing` modules. The
-messages are received from a queue in an internal thread and passed, on
-the same thread, to one or more handlers for processing. While
-:class:`QueueListener` is not itself a handler, it is documented here
-because it works hand-in-hand with :class:`QueueHandler`.
-
-Along with the :class:`QueueHandler` class, :class:`QueueListener` can be used
-to let handlers do their work on a separate thread from the one which does the
-logging. This is important in Web applications and also other service
-applications where threads servicing clients need to respond as quickly as
-possible, while any potentially slow operations (such as sending an email via
-:class:`SMTPHandler`) are done on a separate thread.
-
-.. class:: QueueListener(queue, *handlers)
-
- Returns a new instance of the :class:`QueueListener` class. The instance is
- initialized with the queue to send messages to and a list of handlers which
- will handle entries placed on the queue. The queue can be any queue-
- like object; it's passed as-is to the :meth:`dequeue` method, which needs
- to know how to get messages from it.
-
- .. method:: dequeue(block)
-
- Dequeues a record and return it, optionally blocking.
-
- The base implementation uses ``get()``. You may want to override this
- method if you want to use timeouts or work with custom queue
- implementations.
-
- .. method:: prepare(record)
-
- Prepare a record for handling.
-
- This implementation just returns the passed-in record. You may want to
- override this method if you need to do any custom marshalling or
- manipulation of the record before passing it to the handlers.
-
- .. method:: handle(record)
-
- Handle a record.
-
- This just loops through the handlers offering them the record
- to handle. The actual object passed to the handlers is that which
- is returned from :meth:`prepare`.
-
- .. method:: start()
-
- Starts the listener.
-
- This starts up a background thread to monitor the queue for
- LogRecords to process.
-
- .. method:: stop()
-
- Stops the listener.
-
- This asks the thread to terminate, and then waits for it to do so.
- Note that if you don't call this before your application exits, there
- may be some records still left on the queue, which won't be processed.
-
-
-.. _zeromq-handlers:
-
-Subclassing QueueHandler
-^^^^^^^^^^^^^^^^^^^^^^^^
-
-You can use a :class:`QueueHandler` subclass to send messages to other kinds
-of queues, for example a ZeroMQ 'publish' socket. In the example below,the
-socket is created separately and passed to the handler (as its 'queue')::
-
- import zmq # using pyzmq, the Python binding for ZeroMQ
- import json # for serializing records portably
-
- ctx = zmq.Context()
- sock = zmq.Socket(ctx, zmq.PUB) # or zmq.PUSH, or other suitable value
- sock.bind('tcp://*:5556') # or wherever
-
- class ZeroMQSocketHandler(QueueHandler):
- def enqueue(self, record):
- data = json.dumps(record.__dict__)
- self.queue.send(data)
-
- handler = ZeroMQSocketHandler(sock)
-
-
-Of course there are other ways of organizing this, for example passing in the
-data needed by the handler to create the socket::
-
- class ZeroMQSocketHandler(QueueHandler):
- def __init__(self, uri, socktype=zmq.PUB, ctx=None):
- self.ctx = ctx or zmq.Context()
- socket = zmq.Socket(self.ctx, socktype)
- socket.bind(uri)
- QueueHandler.__init__(self, socket)
-
- def enqueue(self, record):
- data = json.dumps(record.__dict__)
- self.queue.send(data)
-
- def close(self):
- self.queue.close()
-
-
-Subclassing QueueListener
-^^^^^^^^^^^^^^^^^^^^^^^^^
-
-You can also subclass :class:`QueueListener` to get messages from other kinds
-of queues, for example a ZeroMQ 'subscribe' socket. Here's an example::
-
- class ZeroMQSocketListener(QueueListener):
- def __init__(self, uri, *handlers, **kwargs):
- self.ctx = kwargs.get('ctx') or zmq.Context()
- socket = zmq.Socket(self.ctx, zmq.SUB)
- socket.setsockopt(zmq.SUBSCRIBE, '') # subscribe to everything
- socket.connect(uri)
-
- def dequeue(self):
- msg = self.queue.recv()
- return logging.makeLogRecord(json.loads(msg))
-
+For a list of handlers included as standard, see :mod:`logging.handlers`.
.. _formatter-objects:
@@ -3510,9 +506,6 @@ which has a ``filter`` method with the same semantics.
parameter. The returned value should conform to that returned by
:meth:`~Filter.filter`.
-Other uses for filters
-^^^^^^^^^^^^^^^^^^^^^^
-
Although filters are used primarily to filter records based on more
sophisticated criteria than levels, they get to see every record which is
processed by the handler or logger they're attached to: this can be useful if
@@ -3594,8 +587,8 @@ wire).
.. _logrecord-attributes:
-``LogRecord`` attributes
-^^^^^^^^^^^^^^^^^^^^^^^^
+LogRecord attributes
+--------------------
The LogRecord has a number of attributes, most of which are derived from the
parameters to the constructor. (Note that the names do not always correspond
@@ -3741,858 +734,337 @@ because lock implementations in the :mod:`threading` module are not always
re-entrant, and so cannot be invoked from such signal handlers.
-Integration with the warnings module
-------------------------------------
+Module-Level Functions
+----------------------
-The :func:`captureWarnings` function can be used to integrate :mod:`logging`
-with the :mod:`warnings` module.
+In addition to the classes described above, there are a number of module- level
+functions.
-.. function:: captureWarnings(capture)
- This function is used to turn the capture of warnings by logging on and
- off.
+.. function:: getLogger(name=None)
- If *capture* is ``True``, warnings issued by the :mod:`warnings` module will
- be redirected to the logging system. Specifically, a warning will be
- formatted using :func:`warnings.formatwarning` and the resulting string
- logged to a logger named 'py.warnings' with a severity of `WARNING`.
+ Return a logger with the specified name or, if name is ``None``, return a
+ logger which is the root logger of the hierarchy. If specified, the name is
+ typically a dot-separated hierarchical name like *'a'*, *'a.b'* or *'a.b.c.d'*.
+ Choice of these names is entirely up to the developer who is using logging.
- If *capture* is ``False``, the redirection of warnings to the logging system
- will stop, and warnings will be redirected to their original destinations
- (i.e. those in effect before `captureWarnings(True)` was called).
+ All calls to this function with a given name return the same logger instance.
+ This means that logger instances never need to be passed between different parts
+ of an application.
-.. _config-ref:
+.. function:: getLoggerClass()
-Configuration
--------------
+ Return either the standard :class:`Logger` class, or the last class passed to
+ :func:`setLoggerClass`. This function may be called from within a new class
+ definition, to ensure that installing a customised :class:`Logger` class will
+ not undo customisations already applied by other code. For example::
+ class MyLogger(logging.getLoggerClass()):
+ # ... override behaviour here
-.. _logging-config-api:
-Configuration functions
-^^^^^^^^^^^^^^^^^^^^^^^
+.. function:: getLogRecordFactory()
-The following functions configure the logging module. They are located in the
-:mod:`logging.config` module. Their use is optional --- you can configure the
-logging module using these functions or by making calls to the main API (defined
-in :mod:`logging` itself) and defining handlers which are declared either in
-:mod:`logging` or :mod:`logging.handlers`.
+ Return a callable which is used to create a :class:`LogRecord`.
-.. function:: dictConfig(config)
+ .. versionadded:: 3.2
+ This function has been provided, along with :func:`setLogRecordFactory`,
+ to allow developers more control over how the :class:`LogRecord`
+ representing a logging event is constructed.
- Takes the logging configuration from a dictionary. The contents of
- this dictionary are described in :ref:`logging-config-dictschema`
- below.
+ See :func:`setLogRecordFactory` for more information about the how the
+ factory is called.
- If an error is encountered during configuration, this function will
- raise a :exc:`ValueError`, :exc:`TypeError`, :exc:`AttributeError`
- or :exc:`ImportError` with a suitably descriptive message. The
- following is a (possibly incomplete) list of conditions which will
- raise an error:
+.. function:: debug(msg, *args, **kwargs)
- * A ``level`` which is not a string or which is a string not
- corresponding to an actual logging level.
- * A ``propagate`` value which is not a boolean.
- * An id which does not have a corresponding destination.
- * A non-existent handler id found during an incremental call.
- * An invalid logger name.
- * Inability to resolve to an internal or external object.
+ Logs a message with level :const:`DEBUG` on the root logger. The *msg* is the
+ message format string, and the *args* are the arguments which are merged into
+ *msg* using the string formatting operator. (Note that this means that you can
+ use keywords in the format string, together with a single dictionary argument.)
- Parsing is performed by the :class:`DictConfigurator` class, whose
- constructor is passed the dictionary used for configuration, and
- has a :meth:`configure` method. The :mod:`logging.config` module
- has a callable attribute :attr:`dictConfigClass`
- which is initially set to :class:`DictConfigurator`.
- You can replace the value of :attr:`dictConfigClass` with a
- suitable implementation of your own.
+ There are three keyword arguments in *kwargs* which are inspected: *exc_info*
+ which, if it does not evaluate as false, causes exception information to be
+ added to the logging message. If an exception tuple (in the format returned by
+ :func:`sys.exc_info`) is provided, it is used; otherwise, :func:`sys.exc_info`
+ is called to get the exception information.
- :func:`dictConfig` calls :attr:`dictConfigClass` passing
- the specified dictionary, and then calls the :meth:`configure` method on
- the returned object to put the configuration into effect::
+ The second optional keyword argument is *stack_info*, which defaults to
+ False. If specified as True, stack information is added to the logging
+ message, including the actual logging call. Note that this is not the same
+ stack information as that displayed through specifying *exc_info*: The
+ former is stack frames from the bottom of the stack up to the logging call
+ in the current thread, whereas the latter is information about stack frames
+ which have been unwound, following an exception, while searching for
+ exception handlers.
- def dictConfig(config):
- dictConfigClass(config).configure()
+ You can specify *stack_info* independently of *exc_info*, e.g. to just show
+ how you got to a certain point in your code, even when no exceptions were
+ raised. The stack frames are printed following a header line which says::
- For example, a subclass of :class:`DictConfigurator` could call
- ``DictConfigurator.__init__()`` in its own :meth:`__init__()`, then
- set up custom prefixes which would be usable in the subsequent
- :meth:`configure` call. :attr:`dictConfigClass` would be bound to
- this new subclass, and then :func:`dictConfig` could be called exactly as
- in the default, uncustomized state.
+ Stack (most recent call last):
-.. function:: fileConfig(fname[, defaults])
+ This mimics the `Traceback (most recent call last):` which is used when
+ displaying exception frames.
- Reads the logging configuration from a :mod:`configparser`\-format file named
- *fname*. This function can be called several times from an application,
- allowing an end user to select from various pre-canned
- configurations (if the developer provides a mechanism to present the choices
- and load the chosen configuration). Defaults to be passed to the ConfigParser
- can be specified in the *defaults* argument.
+ The third optional keyword argument is *extra* which can be used to pass a
+ dictionary which is used to populate the __dict__ of the LogRecord created for
+ the logging event with user-defined attributes. These custom attributes can then
+ be used as you like. For example, they could be incorporated into logged
+ messages. For example::
+ FORMAT = '%(asctime)-15s %(clientip)s %(user)-8s %(message)s'
+ logging.basicConfig(format=FORMAT)
+ d = {'clientip': '192.168.0.1', 'user': 'fbloggs'}
+ logging.warning('Protocol problem: %s', 'connection reset', extra=d)
-.. function:: listen(port=DEFAULT_LOGGING_CONFIG_PORT)
+ would print something like::
- Starts up a socket server on the specified port, and listens for new
- configurations. If no port is specified, the module's default
- :const:`DEFAULT_LOGGING_CONFIG_PORT` is used. Logging configurations will be
- sent as a file suitable for processing by :func:`fileConfig`. Returns a
- :class:`Thread` instance on which you can call :meth:`start` to start the
- server, and which you can :meth:`join` when appropriate. To stop the server,
- call :func:`stopListening`.
-
- To send a configuration to the socket, read in the configuration file and
- send it to the socket as a string of bytes preceded by a four-byte length
- string packed in binary using ``struct.pack('>L', n)``.
-
-
-.. function:: stopListening()
-
- Stops the listening server which was created with a call to :func:`listen`.
- This is typically called before calling :meth:`join` on the return value from
- :func:`listen`.
+ 2006-02-08 22:20:02,165 192.168.0.1 fbloggs Protocol problem: connection reset
+ The keys in the dictionary passed in *extra* should not clash with the keys used
+ by the logging system. (See the :class:`Formatter` documentation for more
+ information on which keys are used by the logging system.)
-.. _logging-config-dictschema:
+ If you choose to use these attributes in logged messages, you need to exercise
+ some care. In the above example, for instance, the :class:`Formatter` has been
+ set up with a format string which expects 'clientip' and 'user' in the attribute
+ dictionary of the LogRecord. If these are missing, the message will not be
+ logged because a string formatting exception will occur. So in this case, you
+ always need to pass the *extra* dictionary with these keys.
-Configuration dictionary schema
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ While this might be annoying, this feature is intended for use in specialized
+ circumstances, such as multi-threaded servers where the same code executes in
+ many contexts, and interesting conditions which arise are dependent on this
+ context (such as remote client IP address and authenticated user name, in the
+ above example). In such circumstances, it is likely that specialized
+ :class:`Formatter`\ s would be used with particular :class:`Handler`\ s.
-Describing a logging configuration requires listing the various
-objects to create and the connections between them; for example, you
-may create a handler named 'console' and then say that the logger
-named 'startup' will send its messages to the 'console' handler.
-These objects aren't limited to those provided by the :mod:`logging`
-module because you might write your own formatter or handler class.
-The parameters to these classes may also need to include external
-objects such as ``sys.stderr``. The syntax for describing these
-objects and connections is defined in :ref:`logging-config-dict-connections`
-below.
-
-Dictionary Schema Details
-"""""""""""""""""""""""""
-
-The dictionary passed to :func:`dictConfig` must contain the following
-keys:
-
-* *version* - to be set to an integer value representing the schema
- version. The only valid value at present is 1, but having this key
- allows the schema to evolve while still preserving backwards
- compatibility.
-
-All other keys are optional, but if present they will be interpreted
-as described below. In all cases below where a 'configuring dict' is
-mentioned, it will be checked for the special ``'()'`` key to see if a
-custom instantiation is required. If so, the mechanism described in
-:ref:`logging-config-dict-userdef` below is used to create an instance;
-otherwise, the context is used to determine what to instantiate.
-
-* *formatters* - the corresponding value will be a dict in which each
- key is a formatter id and each value is a dict describing how to
- configure the corresponding Formatter instance.
+ .. versionadded:: 3.2
+ The *stack_info* parameter was added.
- The configuring dict is searched for keys ``format`` and ``datefmt``
- (with defaults of ``None``) and these are used to construct a
- :class:`logging.Formatter` instance.
-
-* *filters* - the corresponding value will be a dict in which each key
- is a filter id and each value is a dict describing how to configure
- the corresponding Filter instance.
-
- The configuring dict is searched for the key ``name`` (defaulting to the
- empty string) and this is used to construct a :class:`logging.Filter`
- instance.
-
-* *handlers* - the corresponding value will be a dict in which each
- key is a handler id and each value is a dict describing how to
- configure the corresponding Handler instance.
+.. function:: info(msg, *args, **kwargs)
- The configuring dict is searched for the following keys:
-
- * ``class`` (mandatory). This is the fully qualified name of the
- handler class.
-
- * ``level`` (optional). The level of the handler.
+ Logs a message with level :const:`INFO` on the root logger. The arguments are
+ interpreted as for :func:`debug`.
- * ``formatter`` (optional). The id of the formatter for this
- handler.
- * ``filters`` (optional). A list of ids of the filters for this
- handler.
+.. function:: warning(msg, *args, **kwargs)
- All *other* keys are passed through as keyword arguments to the
- handler's constructor. For example, given the snippet::
-
- handlers:
- console:
- class : logging.StreamHandler
- formatter: brief
- level : INFO
- filters: [allow_foo]
- stream : ext://sys.stdout
- file:
- class : logging.handlers.RotatingFileHandler
- formatter: precise
- filename: logconfig.log
- maxBytes: 1024
- backupCount: 3
-
- the handler with id ``console`` is instantiated as a
- :class:`logging.StreamHandler`, using ``sys.stdout`` as the underlying
- stream. The handler with id ``file`` is instantiated as a
- :class:`logging.handlers.RotatingFileHandler` with the keyword arguments
- ``filename='logconfig.log', maxBytes=1024, backupCount=3``.
-
-* *loggers* - the corresponding value will be a dict in which each key
- is a logger name and each value is a dict describing how to
- configure the corresponding Logger instance.
-
- The configuring dict is searched for the following keys:
-
- * ``level`` (optional). The level of the logger.
-
- * ``propagate`` (optional). The propagation setting of the logger.
-
- * ``filters`` (optional). A list of ids of the filters for this
- logger.
-
- * ``handlers`` (optional). A list of ids of the handlers for this
- logger.
-
- The specified loggers will be configured according to the level,
- propagation, filters and handlers specified.
-
-* *root* - this will be the configuration for the root logger.
- Processing of the configuration will be as for any logger, except
- that the ``propagate`` setting will not be applicable.
-
-* *incremental* - whether the configuration is to be interpreted as
- incremental to the existing configuration. This value defaults to
- ``False``, which means that the specified configuration replaces the
- existing configuration with the same semantics as used by the
- existing :func:`fileConfig` API.
-
- If the specified value is ``True``, the configuration is processed
- as described in the section on :ref:`logging-config-dict-incremental`.
-
-* *disable_existing_loggers* - whether any existing loggers are to be
- disabled. This setting mirrors the parameter of the same name in
- :func:`fileConfig`. If absent, this parameter defaults to ``True``.
- This value is ignored if *incremental* is ``True``.
-
-.. _logging-config-dict-incremental:
-
-Incremental Configuration
-"""""""""""""""""""""""""
-
-It is difficult to provide complete flexibility for incremental
-configuration. For example, because objects such as filters
-and formatters are anonymous, once a configuration is set up, it is
-not possible to refer to such anonymous objects when augmenting a
-configuration.
-
-Furthermore, there is not a compelling case for arbitrarily altering
-the object graph of loggers, handlers, filters, formatters at
-run-time, once a configuration is set up; the verbosity of loggers and
-handlers can be controlled just by setting levels (and, in the case of
-loggers, propagation flags). Changing the object graph arbitrarily in
-a safe way is problematic in a multi-threaded environment; while not
-impossible, the benefits are not worth the complexity it adds to the
-implementation.
-
-Thus, when the ``incremental`` key of a configuration dict is present
-and is ``True``, the system will completely ignore any ``formatters`` and
-``filters`` entries, and process only the ``level``
-settings in the ``handlers`` entries, and the ``level`` and
-``propagate`` settings in the ``loggers`` and ``root`` entries.
-
-Using a value in the configuration dict lets configurations to be sent
-over the wire as pickled dicts to a socket listener. Thus, the logging
-verbosity of a long-running application can be altered over time with
-no need to stop and restart the application.
-
-.. _logging-config-dict-connections:
-
-Object connections
-""""""""""""""""""
-
-The schema describes a set of logging objects - loggers,
-handlers, formatters, filters - which are connected to each other in
-an object graph. Thus, the schema needs to represent connections
-between the objects. For example, say that, once configured, a
-particular logger has attached to it a particular handler. For the
-purposes of this discussion, we can say that the logger represents the
-source, and the handler the destination, of a connection between the
-two. Of course in the configured objects this is represented by the
-logger holding a reference to the handler. In the configuration dict,
-this is done by giving each destination object an id which identifies
-it unambiguously, and then using the id in the source object's
-configuration to indicate that a connection exists between the source
-and the destination object with that id.
-
-So, for example, consider the following YAML snippet::
-
- formatters:
- brief:
- # configuration for formatter with id 'brief' goes here
- precise:
- # configuration for formatter with id 'precise' goes here
- handlers:
- h1: #This is an id
- # configuration of handler with id 'h1' goes here
- formatter: brief
- h2: #This is another id
- # configuration of handler with id 'h2' goes here
- formatter: precise
- loggers:
- foo.bar.baz:
- # other configuration for logger 'foo.bar.baz'
- handlers: [h1, h2]
-
-(Note: YAML used here because it's a little more readable than the
-equivalent Python source form for the dictionary.)
-
-The ids for loggers are the logger names which would be used
-programmatically to obtain a reference to those loggers, e.g.
-``foo.bar.baz``. The ids for Formatters and Filters can be any string
-value (such as ``brief``, ``precise`` above) and they are transient,
-in that they are only meaningful for processing the configuration
-dictionary and used to determine connections between objects, and are
-not persisted anywhere when the configuration call is complete.
-
-The above snippet indicates that logger named ``foo.bar.baz`` should
-have two handlers attached to it, which are described by the handler
-ids ``h1`` and ``h2``. The formatter for ``h1`` is that described by id
-``brief``, and the formatter for ``h2`` is that described by id
-``precise``.
-
-
-.. _logging-config-dict-userdef:
-
-User-defined objects
-""""""""""""""""""""
-
-The schema supports user-defined objects for handlers, filters and
-formatters. (Loggers do not need to have different types for
-different instances, so there is no support in this configuration
-schema for user-defined logger classes.)
-
-Objects to be configured are described by dictionaries
-which detail their configuration. In some places, the logging system
-will be able to infer from the context how an object is to be
-instantiated, but when a user-defined object is to be instantiated,
-the system will not know how to do this. In order to provide complete
-flexibility for user-defined object instantiation, the user needs
-to provide a 'factory' - a callable which is called with a
-configuration dictionary and which returns the instantiated object.
-This is signalled by an absolute import path to the factory being
-made available under the special key ``'()'``. Here's a concrete
-example::
-
- formatters:
- brief:
- format: '%(message)s'
- default:
- format: '%(asctime)s %(levelname)-8s %(name)-15s %(message)s'
- datefmt: '%Y-%m-%d %H:%M:%S'
- custom:
- (): my.package.customFormatterFactory
- bar: baz
- spam: 99.9
- answer: 42
-
-The above YAML snippet defines three formatters. The first, with id
-``brief``, is a standard :class:`logging.Formatter` instance with the
-specified format string. The second, with id ``default``, has a
-longer format and also defines the time format explicitly, and will
-result in a :class:`logging.Formatter` initialized with those two format
-strings. Shown in Python source form, the ``brief`` and ``default``
-formatters have configuration sub-dictionaries::
-
- {
- 'format' : '%(message)s'
- }
-
-and::
-
- {
- 'format' : '%(asctime)s %(levelname)-8s %(name)-15s %(message)s',
- 'datefmt' : '%Y-%m-%d %H:%M:%S'
- }
-
-respectively, and as these dictionaries do not contain the special key
-``'()'``, the instantiation is inferred from the context: as a result,
-standard :class:`logging.Formatter` instances are created. The
-configuration sub-dictionary for the third formatter, with id
-``custom``, is::
-
- {
- '()' : 'my.package.customFormatterFactory',
- 'bar' : 'baz',
- 'spam' : 99.9,
- 'answer' : 42
- }
-
-and this contains the special key ``'()'``, which means that
-user-defined instantiation is wanted. In this case, the specified
-factory callable will be used. If it is an actual callable it will be
-used directly - otherwise, if you specify a string (as in the example)
-the actual callable will be located using normal import mechanisms.
-The callable will be called with the **remaining** items in the
-configuration sub-dictionary as keyword arguments. In the above
-example, the formatter with id ``custom`` will be assumed to be
-returned by the call::
-
- my.package.customFormatterFactory(bar='baz', spam=99.9, answer=42)
-
-The key ``'()'`` has been used as the special key because it is not a
-valid keyword parameter name, and so will not clash with the names of
-the keyword arguments used in the call. The ``'()'`` also serves as a
-mnemonic that the corresponding value is a callable.
-
-
-.. _logging-config-dict-externalobj:
-
-Access to external objects
-""""""""""""""""""""""""""
-
-There are times where a configuration needs to refer to objects
-external to the configuration, for example ``sys.stderr``. If the
-configuration dict is constructed using Python code, this is
-straightforward, but a problem arises when the configuration is
-provided via a text file (e.g. JSON, YAML). In a text file, there is
-no standard way to distinguish ``sys.stderr`` from the literal string
-``'sys.stderr'``. To facilitate this distinction, the configuration
-system looks for certain special prefixes in string values and
-treat them specially. For example, if the literal string
-``'ext://sys.stderr'`` is provided as a value in the configuration,
-then the ``ext://`` will be stripped off and the remainder of the
-value processed using normal import mechanisms.
-
-The handling of such prefixes is done in a way analogous to protocol
-handling: there is a generic mechanism to look for prefixes which
-match the regular expression ``^(?P<prefix>[a-z]+)://(?P<suffix>.*)$``
-whereby, if the ``prefix`` is recognised, the ``suffix`` is processed
-in a prefix-dependent manner and the result of the processing replaces
-the string value. If the prefix is not recognised, then the string
-value will be left as-is.
-
-
-.. _logging-config-dict-internalobj:
-
-Access to internal objects
-""""""""""""""""""""""""""
-
-As well as external objects, there is sometimes also a need to refer
-to objects in the configuration. This will be done implicitly by the
-configuration system for things that it knows about. For example, the
-string value ``'DEBUG'`` for a ``level`` in a logger or handler will
-automatically be converted to the value ``logging.DEBUG``, and the
-``handlers``, ``filters`` and ``formatter`` entries will take an
-object id and resolve to the appropriate destination object.
-
-However, a more generic mechanism is needed for user-defined
-objects which are not known to the :mod:`logging` module. For
-example, consider :class:`logging.handlers.MemoryHandler`, which takes
-a ``target`` argument which is another handler to delegate to. Since
-the system already knows about this class, then in the configuration,
-the given ``target`` just needs to be the object id of the relevant
-target handler, and the system will resolve to the handler from the
-id. If, however, a user defines a ``my.package.MyHandler`` which has
-an ``alternate`` handler, the configuration system would not know that
-the ``alternate`` referred to a handler. To cater for this, a generic
-resolution system allows the user to specify::
-
- handlers:
- file:
- # configuration of file handler goes here
-
- custom:
- (): my.package.MyHandler
- alternate: cfg://handlers.file
-
-The literal string ``'cfg://handlers.file'`` will be resolved in an
-analogous way to strings with the ``ext://`` prefix, but looking
-in the configuration itself rather than the import namespace. The
-mechanism allows access by dot or by index, in a similar way to
-that provided by ``str.format``. Thus, given the following snippet::
-
- handlers:
- email:
- class: logging.handlers.SMTPHandler
- mailhost: localhost
- fromaddr: my_app@domain.tld
- toaddrs:
- - support_team@domain.tld
- - dev_team@domain.tld
- subject: Houston, we have a problem.
-
-in the configuration, the string ``'cfg://handlers'`` would resolve to
-the dict with key ``handlers``, the string ``'cfg://handlers.email``
-would resolve to the dict with key ``email`` in the ``handlers`` dict,
-and so on. The string ``'cfg://handlers.email.toaddrs[1]`` would
-resolve to ``'dev_team.domain.tld'`` and the string
-``'cfg://handlers.email.toaddrs[0]'`` would resolve to the value
-``'support_team@domain.tld'``. The ``subject`` value could be accessed
-using either ``'cfg://handlers.email.subject'`` or, equivalently,
-``'cfg://handlers.email[subject]'``. The latter form only needs to be
-used if the key contains spaces or non-alphanumeric characters. If an
-index value consists only of decimal digits, access will be attempted
-using the corresponding integer value, falling back to the string
-value if needed.
-
-Given a string ``cfg://handlers.myhandler.mykey.123``, this will
-resolve to ``config_dict['handlers']['myhandler']['mykey']['123']``.
-If the string is specified as ``cfg://handlers.myhandler.mykey[123]``,
-the system will attempt to retrieve the value from
-``config_dict['handlers']['myhandler']['mykey'][123]``, and fall back
-to ``config_dict['handlers']['myhandler']['mykey']['123']`` if that
-fails.
-
-.. _logging-config-fileformat:
-
-Configuration file format
-^^^^^^^^^^^^^^^^^^^^^^^^^
-
-The configuration file format understood by :func:`fileConfig` is based on
-:mod:`configparser` functionality. The file must contain sections called
-``[loggers]``, ``[handlers]`` and ``[formatters]`` which identify by name the
-entities of each type which are defined in the file. For each such entity, there
-is a separate section which identifies how that entity is configured. Thus, for
-a logger named ``log01`` in the ``[loggers]`` section, the relevant
-configuration details are held in a section ``[logger_log01]``. Similarly, a
-handler called ``hand01`` in the ``[handlers]`` section will have its
-configuration held in a section called ``[handler_hand01]``, while a formatter
-called ``form01`` in the ``[formatters]`` section will have its configuration
-specified in a section called ``[formatter_form01]``. The root logger
-configuration must be specified in a section called ``[logger_root]``.
-
-Examples of these sections in the file are given below. ::
-
- [loggers]
- keys=root,log02,log03,log04,log05,log06,log07
-
- [handlers]
- keys=hand01,hand02,hand03,hand04,hand05,hand06,hand07,hand08,hand09
-
- [formatters]
- keys=form01,form02,form03,form04,form05,form06,form07,form08,form09
-
-The root logger must specify a level and a list of handlers. An example of a
-root logger section is given below. ::
-
- [logger_root]
- level=NOTSET
- handlers=hand01
-
-The ``level`` entry can be one of ``DEBUG, INFO, WARNING, ERROR, CRITICAL`` or
-``NOTSET``. For the root logger only, ``NOTSET`` means that all messages will be
-logged. Level values are :func:`eval`\ uated in the context of the ``logging``
-package's namespace.
-
-The ``handlers`` entry is a comma-separated list of handler names, which must
-appear in the ``[handlers]`` section. These names must appear in the
-``[handlers]`` section and have corresponding sections in the configuration
-file.
-
-For loggers other than the root logger, some additional information is required.
-This is illustrated by the following example. ::
-
- [logger_parser]
- level=DEBUG
- handlers=hand01
- propagate=1
- qualname=compiler.parser
-
-The ``level`` and ``handlers`` entries are interpreted as for the root logger,
-except that if a non-root logger's level is specified as ``NOTSET``, the system
-consults loggers higher up the hierarchy to determine the effective level of the
-logger. The ``propagate`` entry is set to 1 to indicate that messages must
-propagate to handlers higher up the logger hierarchy from this logger, or 0 to
-indicate that messages are **not** propagated to handlers up the hierarchy. The
-``qualname`` entry is the hierarchical channel name of the logger, that is to
-say the name used by the application to get the logger.
-
-Sections which specify handler configuration are exemplified by the following.
-::
-
- [handler_hand01]
- class=StreamHandler
- level=NOTSET
- formatter=form01
- args=(sys.stdout,)
-
-The ``class`` entry indicates the handler's class (as determined by :func:`eval`
-in the ``logging`` package's namespace). The ``level`` is interpreted as for
-loggers, and ``NOTSET`` is taken to mean 'log everything'.
-
-The ``formatter`` entry indicates the key name of the formatter for this
-handler. If blank, a default formatter (``logging._defaultFormatter``) is used.
-If a name is specified, it must appear in the ``[formatters]`` section and have
-a corresponding section in the configuration file.
-
-The ``args`` entry, when :func:`eval`\ uated in the context of the ``logging``
-package's namespace, is the list of arguments to the constructor for the handler
-class. Refer to the constructors for the relevant handlers, or to the examples
-below, to see how typical entries are constructed. ::
-
- [handler_hand02]
- class=FileHandler
- level=DEBUG
- formatter=form02
- args=('python.log', 'w')
-
- [handler_hand03]
- class=handlers.SocketHandler
- level=INFO
- formatter=form03
- args=('localhost', handlers.DEFAULT_TCP_LOGGING_PORT)
-
- [handler_hand04]
- class=handlers.DatagramHandler
- level=WARN
- formatter=form04
- args=('localhost', handlers.DEFAULT_UDP_LOGGING_PORT)
-
- [handler_hand05]
- class=handlers.SysLogHandler
- level=ERROR
- formatter=form05
- args=(('localhost', handlers.SYSLOG_UDP_PORT), handlers.SysLogHandler.LOG_USER)
-
- [handler_hand06]
- class=handlers.NTEventLogHandler
- level=CRITICAL
- formatter=form06
- args=('Python Application', '', 'Application')
-
- [handler_hand07]
- class=handlers.SMTPHandler
- level=WARN
- formatter=form07
- args=('localhost', 'from@abc', ['user1@abc', 'user2@xyz'], 'Logger Subject')
-
- [handler_hand08]
- class=handlers.MemoryHandler
- level=NOTSET
- formatter=form08
- target=
- args=(10, ERROR)
-
- [handler_hand09]
- class=handlers.HTTPHandler
- level=NOTSET
- formatter=form09
- args=('localhost:9022', '/log', 'GET')
-
-Sections which specify formatter configuration are typified by the following. ::
-
- [formatter_form01]
- format=F1 %(asctime)s %(levelname)s %(message)s
- datefmt=
- class=logging.Formatter
-
-The ``format`` entry is the overall format string, and the ``datefmt`` entry is
-the :func:`strftime`\ -compatible date/time format string. If empty, the
-package substitutes ISO8601 format date/times, which is almost equivalent to
-specifying the date format string ``'%Y-%m-%d %H:%M:%S'``. The ISO8601 format
-also specifies milliseconds, which are appended to the result of using the above
-format string, with a comma separator. An example time in ISO8601 format is
-``2003-01-23 00:29:50,411``.
-
-The ``class`` entry is optional. It indicates the name of the formatter's class
-(as a dotted module and class name.) This option is useful for instantiating a
-:class:`Formatter` subclass. Subclasses of :class:`Formatter` can present
-exception tracebacks in an expanded or condensed format.
-
-
-Configuration server example
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Here is an example of a module using the logging configuration server::
-
- import logging
- import logging.config
- import time
- import os
-
- # read initial config file
- logging.config.fileConfig('logging.conf')
-
- # create and start listener on port 9999
- t = logging.config.listen(9999)
- t.start()
-
- logger = logging.getLogger('simpleExample')
-
- try:
- # loop through logging calls to see the difference
- # new configurations make, until Ctrl+C is pressed
- while True:
- logger.debug('debug message')
- logger.info('info message')
- logger.warn('warn message')
- logger.error('error message')
- logger.critical('critical message')
- time.sleep(5)
- except KeyboardInterrupt:
- # cleanup
- logging.config.stopListening()
- t.join()
-
-And here is a script that takes a filename and sends that file to the server,
-properly preceded with the binary-encoded length, as the new logging
-configuration::
-
- #!/usr/bin/env python
- import socket, sys, struct
-
- data_to_send = open(sys.argv[1], 'r').read()
-
- HOST = 'localhost'
- PORT = 9999
- s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
- print('connecting...')
- s.connect((HOST, PORT))
- print('sending config...')
- s.send(struct.pack('>L', len(data_to_send)))
- s.send(data_to_send)
- s.close()
- print('complete')
-
-
-More examples
--------------
+ Logs a message with level :const:`WARNING` on the root logger. The arguments are
+ interpreted as for :func:`debug`.
+
+
+.. function:: error(msg, *args, **kwargs)
+
+ Logs a message with level :const:`ERROR` on the root logger. The arguments are
+ interpreted as for :func:`debug`.
+
+
+.. function:: critical(msg, *args, **kwargs)
+
+ Logs a message with level :const:`CRITICAL` on the root logger. The arguments
+ are interpreted as for :func:`debug`.
+
+
+.. function:: exception(msg, *args)
+
+ Logs a message with level :const:`ERROR` on the root logger. The arguments are
+ interpreted as for :func:`debug`. Exception info is added to the logging
+ message. This function should only be called from an exception handler.
+
+.. function:: log(level, msg, *args, **kwargs)
+
+ Logs a message with level *level* on the root logger. The other arguments are
+ interpreted as for :func:`debug`.
+
+ PLEASE NOTE: The above module-level functions which delegate to the root
+ logger should *not* be used in threads, in versions of Python earlier than
+ 2.7.1 and 3.2, unless at least one handler has been added to the root
+ logger *before* the threads are started. These convenience functions call
+ :func:`basicConfig` to ensure that at least one handler is available; in
+ earlier versions of Python, this can (under rare circumstances) lead to
+ handlers being added multiple times to the root logger, which can in turn
+ lead to multiple messages for the same event.
+
+.. function:: disable(lvl)
+
+ Provides an overriding level *lvl* for all loggers which takes precedence over
+ the logger's own level. When the need arises to temporarily throttle logging
+ output down across the whole application, this function can be useful. Its
+ effect is to disable all logging calls of severity *lvl* and below, so that
+ if you call it with a value of INFO, then all INFO and DEBUG events would be
+ discarded, whereas those of severity WARNING and above would be processed
+ according to the logger's effective level.
+
+
+.. function:: addLevelName(lvl, levelName)
+
+ Associates level *lvl* with text *levelName* in an internal dictionary, which is
+ used to map numeric levels to a textual representation, for example when a
+ :class:`Formatter` formats a message. This function can also be used to define
+ your own levels. The only constraints are that all levels used must be
+ registered using this function, levels should be positive integers and they
+ should increase in increasing order of severity.
+
+ NOTE: If you are thinking of defining your own levels, please see the section
+ on :ref:`custom-levels`.
+
+.. function:: getLevelName(lvl)
+
+ Returns the textual representation of logging level *lvl*. If the level is one
+ of the predefined levels :const:`CRITICAL`, :const:`ERROR`, :const:`WARNING`,
+ :const:`INFO` or :const:`DEBUG` then you get the corresponding string. If you
+ have associated levels with names using :func:`addLevelName` then the name you
+ have associated with *lvl* is returned. If a numeric value corresponding to one
+ of the defined levels is passed in, the corresponding string representation is
+ returned. Otherwise, the string 'Level %s' % lvl is returned.
+
+
+.. function:: makeLogRecord(attrdict)
+
+ Creates and returns a new :class:`LogRecord` instance whose attributes are
+ defined by *attrdict*. This function is useful for taking a pickled
+ :class:`LogRecord` attribute dictionary, sent over a socket, and reconstituting
+ it as a :class:`LogRecord` instance at the receiving end.
+
+
+.. function:: basicConfig(**kwargs)
+
+ Does basic configuration for the logging system by creating a
+ :class:`StreamHandler` with a default :class:`Formatter` and adding it to the
+ root logger. The functions :func:`debug`, :func:`info`, :func:`warning`,
+ :func:`error` and :func:`critical` will call :func:`basicConfig` automatically
+ if no handlers are defined for the root logger.
+
+ This function does nothing if the root logger already has handlers
+ configured for it.
+
+ PLEASE NOTE: This function should be called from the main thread
+ before other threads are started. In versions of Python prior to
+ 2.7.1 and 3.2, if this function is called from multiple threads,
+ it is possible (in rare circumstances) that a handler will be added
+ to the root logger more than once, leading to unexpected results
+ such as messages being duplicated in the log.
+
+ The following keyword arguments are supported.
+
+ +--------------+---------------------------------------------+
+ | Format | Description |
+ +==============+=============================================+
+ | ``filename`` | Specifies that a FileHandler be created, |
+ | | using the specified filename, rather than a |
+ | | StreamHandler. |
+ +--------------+---------------------------------------------+
+ | ``filemode`` | Specifies the mode to open the file, if |
+ | | filename is specified (if filemode is |
+ | | unspecified, it defaults to 'a'). |
+ +--------------+---------------------------------------------+
+ | ``format`` | Use the specified format string for the |
+ | | handler. |
+ +--------------+---------------------------------------------+
+ | ``datefmt`` | Use the specified date/time format. |
+ +--------------+---------------------------------------------+
+ | ``style`` | If ``format`` is specified, use this style |
+ | | for the format string. One of '%', '{' or |
+ | | '$' for %-formatting, :meth:`str.format` or |
+ | | :class:`string.Template` respectively, and |
+ | | defaulting to '%' if not specified. |
+ +--------------+---------------------------------------------+
+ | ``level`` | Set the root logger level to the specified |
+ | | level. |
+ +--------------+---------------------------------------------+
+ | ``stream`` | Use the specified stream to initialize the |
+ | | StreamHandler. Note that this argument is |
+ | | incompatible with 'filename' - if both are |
+ | | present, 'stream' is ignored. |
+ +--------------+---------------------------------------------+
+
+ .. versionchanged:: 3.2
+ The ``style`` argument was added.
+
+
+.. function:: shutdown()
+
+ Informs the logging system to perform an orderly shutdown by flushing and
+ closing all handlers. This should be called at application exit and no
+ further use of the logging system should be made after this call.
+
+
+.. function:: setLoggerClass(klass)
+
+ Tells the logging system to use the class *klass* when instantiating a logger.
+ The class should define :meth:`__init__` such that only a name argument is
+ required, and the :meth:`__init__` should call :meth:`Logger.__init__`. This
+ function is typically called before any loggers are instantiated by applications
+ which need to use custom logger behavior.
-Multiple handlers and formatters
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Loggers are plain Python objects. The :func:`addHandler` method has no minimum
-or maximum quota for the number of handlers you may add. Sometimes it will be
-beneficial for an application to log all messages of all severities to a text
-file while simultaneously logging errors or above to the console. To set this
-up, simply configure the appropriate handlers. The logging calls in the
-application code will remain unchanged. Here is a slight modification to the
-previous simple module-based configuration example::
-
- import logging
-
- logger = logging.getLogger('simple_example')
- logger.setLevel(logging.DEBUG)
- # create file handler which logs even debug messages
- fh = logging.FileHandler('spam.log')
- fh.setLevel(logging.DEBUG)
- # create console handler with a higher log level
- ch = logging.StreamHandler()
- ch.setLevel(logging.ERROR)
- # create formatter and add it to the handlers
- formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
- ch.setFormatter(formatter)
- fh.setFormatter(formatter)
- # add the handlers to logger
- logger.addHandler(ch)
- logger.addHandler(fh)
-
- # 'application' code
- logger.debug('debug message')
- logger.info('info message')
- logger.warn('warn message')
- logger.error('error message')
- logger.critical('critical message')
-
-Notice that the 'application' code does not care about multiple handlers. All
-that changed was the addition and configuration of a new handler named *fh*.
-
-The ability to create new handlers with higher- or lower-severity filters can be
-very helpful when writing and testing an application. Instead of using many
-``print`` statements for debugging, use ``logger.debug``: Unlike the print
-statements, which you will have to delete or comment out later, the logger.debug
-statements can remain intact in the source code and remain dormant until you
-need them again. At that time, the only change that needs to happen is to
-modify the severity level of the logger and/or handler to debug.
-
-
-Using logging in multiple modules
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-It was mentioned above that multiple calls to
-``logging.getLogger('someLogger')`` return a reference to the same logger
-object. This is true not only within the same module, but also across modules
-as long as it is in the same Python interpreter process. It is true for
-references to the same object; additionally, application code can define and
-configure a parent logger in one module and create (but not configure) a child
-logger in a separate module, and all logger calls to the child will pass up to
-the parent. Here is a main module::
-
- import logging
- import auxiliary_module
-
- # create logger with 'spam_application'
- logger = logging.getLogger('spam_application')
- logger.setLevel(logging.DEBUG)
- # create file handler which logs even debug messages
- fh = logging.FileHandler('spam.log')
- fh.setLevel(logging.DEBUG)
- # create console handler with a higher log level
- ch = logging.StreamHandler()
- ch.setLevel(logging.ERROR)
- # create formatter and add it to the handlers
- formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
- fh.setFormatter(formatter)
- ch.setFormatter(formatter)
- # add the handlers to the logger
- logger.addHandler(fh)
- logger.addHandler(ch)
-
- logger.info('creating an instance of auxiliary_module.Auxiliary')
- a = auxiliary_module.Auxiliary()
- logger.info('created an instance of auxiliary_module.Auxiliary')
- logger.info('calling auxiliary_module.Auxiliary.do_something')
- a.do_something()
- logger.info('finished auxiliary_module.Auxiliary.do_something')
- logger.info('calling auxiliary_module.some_function()')
- auxiliary_module.some_function()
- logger.info('done with auxiliary_module.some_function()')
-
-Here is the auxiliary module::
-
- import logging
-
- # create logger
- module_logger = logging.getLogger('spam_application.auxiliary')
-
- class Auxiliary:
- def __init__(self):
- self.logger = logging.getLogger('spam_application.auxiliary.Auxiliary')
- self.logger.info('creating an instance of Auxiliary')
- def do_something(self):
- self.logger.info('doing something')
- a = 1 + 1
- self.logger.info('done doing something')
-
- def some_function():
- module_logger.info('received a call to "some_function"')
-
-The output looks like this::
-
- 2005-03-23 23:47:11,663 - spam_application - INFO -
- creating an instance of auxiliary_module.Auxiliary
- 2005-03-23 23:47:11,665 - spam_application.auxiliary.Auxiliary - INFO -
- creating an instance of Auxiliary
- 2005-03-23 23:47:11,665 - spam_application - INFO -
- created an instance of auxiliary_module.Auxiliary
- 2005-03-23 23:47:11,668 - spam_application - INFO -
- calling auxiliary_module.Auxiliary.do_something
- 2005-03-23 23:47:11,668 - spam_application.auxiliary.Auxiliary - INFO -
- doing something
- 2005-03-23 23:47:11,669 - spam_application.auxiliary.Auxiliary - INFO -
- done doing something
- 2005-03-23 23:47:11,670 - spam_application - INFO -
- finished auxiliary_module.Auxiliary.do_something
- 2005-03-23 23:47:11,671 - spam_application - INFO -
- calling auxiliary_module.some_function()
- 2005-03-23 23:47:11,672 - spam_application.auxiliary - INFO -
- received a call to 'some_function'
- 2005-03-23 23:47:11,673 - spam_application - INFO -
- done with auxiliary_module.some_function()
+
+.. function:: setLogRecordFactory(factory)
+
+ Set a callable which is used to create a :class:`LogRecord`.
+
+ :param factory: The factory callable to be used to instantiate a log record.
+
+ .. versionadded:: 3.2
+ This function has been provided, along with :func:`getLogRecordFactory`, to
+ allow developers more control over how the :class:`LogRecord` representing
+ a logging event is constructed.
+
+ The factory has the following signature:
+
+ ``factory(name, level, fn, lno, msg, args, exc_info, func=None, sinfo=None, **kwargs)``
+
+ :name: The logger name.
+ :level: The logging level (numeric).
+ :fn: The full pathname of the file where the logging call was made.
+ :lno: The line number in the file where the logging call was made.
+ :msg: The logging message.
+ :args: The arguments for the logging message.
+ :exc_info: An exception tuple, or None.
+ :func: The name of the function or method which invoked the logging
+ call.
+ :sinfo: A stack traceback such as is provided by
+ :func:`traceback.print_stack`, showing the call hierarchy.
+ :kwargs: Additional keyword arguments.
+
+
+Integration with the warnings module
+------------------------------------
+
+The :func:`captureWarnings` function can be used to integrate :mod:`logging`
+with the :mod:`warnings` module.
+
+.. function:: captureWarnings(capture)
+
+ This function is used to turn the capture of warnings by logging on and
+ off.
+
+ If *capture* is ``True``, warnings issued by the :mod:`warnings` module will
+ be redirected to the logging system. Specifically, a warning will be
+ formatted using :func:`warnings.formatwarning` and the resulting string
+ logged to a logger named 'py.warnings' with a severity of `WARNING`.
+
+ If *capture* is ``False``, the redirection of warnings to the logging system
+ will stop, and warnings will be redirected to their original destinations
+ (i.e. those in effect before `captureWarnings(True)` was called).
+
+
+.. seealso::
+
+ Module :mod:`logging.config`
+ Configuration API for the logging module.
+
+ Module :mod:`logging.handlers`
+ Useful handlers included with the logging module.
+
+ :pep:`282` - A Logging System
+ The proposal which described this feature for inclusion in the Python standard
+ library.
+
+ `Original Python logging package <http://www.red-dove.com/python_logging.html>`_
+ This is the original source for the :mod:`logging` package. The version of the
+ package available from this site is suitable for use with Python 1.5.2, 2.1.x
+ and 2.2.x, which do not include the :mod:`logging` package in the standard
+ library.