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diff --git a/Doc/library/zipapp.rst b/Doc/library/zipapp.rst new file mode 100644 index 0000000..b4484c8 --- /dev/null +++ b/Doc/library/zipapp.rst @@ -0,0 +1,259 @@ +:mod:`zipapp` --- Manage executable python zip archives +======================================================= + +.. module:: zipapp + :synopsis: Manage executable python zip archives + + +.. index:: + single: Executable Zip Files + +.. versionadded:: 3.5 + +**Source code:** :source:`Lib/zipapp.py` + +-------------- + +This module provides tools to manage the creation of zip files containing +Python code, which can be :ref:`executed directly by the Python interpreter +<using-on-interface-options>`. The module provides both a +:ref:`zipapp-command-line-interface` and a :ref:`zipapp-python-api`. + + +Basic Example +------------- + +The following example shows how the :ref:`command-line-interface` +can be used to create an executable archive from a directory containing +Python code. When run, the archive will execute the ``main`` function from +the module ``myapp`` in the archive. + +.. code-block:: sh + + $ python -m zipapp myapp -m "myapp:main" + $ python myapp.pyz + <output from myapp> + + +.. _zipapp-command-line-interface: + +Command-Line Interface +---------------------- + +When called as a program from the command line, the following form is used: + +.. code-block:: sh + + $ python -m zipapp source [options] + +If *source* is a directory, this will create an archive from the contents of +*source*. If *source* is a file, it should be an archive, and it will be +copied to the target archive (or the contents of its shebang line will be +displayed if the --info option is specified). + +The following options are understood: + +.. program:: zipapp + +.. cmdoption:: -o <output>, --output=<output> + + Write the output to a file named *output*. If this option is not specified, + the output filename will be the same as the input *source*, with the + extension ``.pyz`` added. If an explicit filename is given, it is used as + is (so a ``.pyz`` extension should be included if required). + + An output filename must be specified if the *source* is an archive (and in + that case, *output* must not be the same as *source*). + +.. cmdoption:: -p <interpreter>, --python=<interpreter> + + Add a ``#!`` line to the archive specifying *interpreter* as the command + to run. Also, on POSIX, make the archive executable. The default is to + write no ``#!`` line, and not make the file executable. + +.. cmdoption:: -m <mainfn>, --main=<mainfn> + + Write a ``__main__.py`` file to the archive that executes *mainfn*. The + *mainfn* argument should have the form "pkg.mod:fn", where "pkg.mod" is a + package/module in the archive, and "fn" is a callable in the given module. + The ``__main__.py`` file will execute that callable. + + :option:`--main` cannot be specified when copying an archive. + +.. cmdoption:: --info + + Display the interpreter embedded in the archive, for diagnostic purposes. In + this case, any other options are ignored and SOURCE must be an archive, not a + directory. + +.. cmdoption:: -h, --help + + Print a short usage message and exit. + + +.. _zipapp-python-api: + +Python API +---------- + +The module defines two convenience functions: + + +.. function:: create_archive(source, target=None, interpreter=None, main=None) + + Create an application archive from *source*. The source can be any + of the following: + + * The name of a directory, or a :class:`pathlib.Path` object referring + to a directory, in which case a new application archive will be + created from the content of that directory. + * The name of an existing application archive file, or a :class:`pathlib.Path` + object referring to such a file, in which case the file is copied to + the target (modifying it to reflect the value given for the *interpreter* + argument). The file name should include the ``.pyz`` extension, if required. + * A file object open for reading in bytes mode. The content of the + file should be an application archive, and the file object is + assumed to be positioned at the start of the archive. + + The *target* argument determines where the resulting archive will be + written: + + * If it is the name of a file, or a :class:`pathlb.Path` object, + the archive will be written to that file. + * If it is an open file object, the archive will be written to that + file object, which must be open for writing in bytes mode. + * If the target is omitted (or None), the source must be a directory + and the target will be a file with the same name as the source, with + a ``.pyz`` extension added. + + The *interpreter* argument specifies the name of the Python + interpreter with which the archive will be executed. It is written as + a "shebang" line at the start of the archive. On POSIX, this will be + interpreted by the OS, and on Windows it will be handled by the Python + launcher. Omitting the *interpreter* results in no shebang line being + written. If an interpreter is specified, and the target is a + filename, the executable bit of the target file will be set. + + The *main* argument specifies the name of a callable which will be + used as the main program for the archive. It can only be specified if + the source is a directory, and the source does not already contain a + ``__main__.py`` file. The *main* argument should take the form + "pkg.module:callable" and the archive will be run by importing + "pkg.module" and executing the given callable with no arguments. It + is an error to omit *main* if the source is a directory and does not + contain a ``__main__.py`` file, as otherwise the resulting archive + would not be executable. + + If a file object is specified for *source* or *target*, it is the + caller's responsibility to close it after calling create_archive. + + When copying an existing archive, file objects supplied only need + ``read`` and ``readline``, or ``write`` methods. When creating an + archive from a directory, if the target is a file object it will be + passed to the ``zipfile.ZipFile`` class, and must supply the methods + needed by that class. + +.. function:: get_interpreter(archive) + + Return the interpreter specified in the ``#!`` line at the start of the + archive. If there is no ``#!`` line, return :const:`None`. + The *archive* argument can be a filename or a file-like object open + for reading in bytes mode. It is assumed to be at the start of the archive. + + +.. _zipapp-examples: + +Examples +-------- + +Pack up a directory into an archive, and run it. + +.. code-block:: sh + + $ python -m zipapp myapp + $ python myapp.pyz + <output from myapp> + +The same can be done using the :func:`create_archive` functon:: + + >>> import zipapp + >>> zipapp.create_archive('myapp.pyz', 'myapp') + +To make the application directly executable on POSIX, specify an interpreter +to use. + +.. code-block:: sh + + $ python -m zipapp myapp -p "/usr/bin/env python" + $ ./myapp.pyz + <output from myapp> + +To replace the shebang line on an existing archive, create a modified archive +using the :func:`create_archive` function:: + + >>> import zipapp + >>> zipapp.create_archive('old_archive.pyz', 'new_archive.pyz', '/usr/bin/python3') + +To update the file in place, do the replacement in memory using a :class:`BytesIO` +object, and then overwrite the source afterwards. Note that there is a risk +when overwriting a file in place that an error will result in the loss of +the original file. This code does not protect against such errors, but +production code should do so. Also, this method will only work if the archive +fits in memory:: + + >>> import zipapp + >>> import io + >>> temp = io.BytesIO() + >>> zipapp.create_archive('myapp.pyz', temp, '/usr/bin/python2') + >>> with open('myapp.pyz', 'wb') as f: + >>> f.write(temp.getvalue()) + +Note that if you specify an interpreter and then distribute your application +archive, you need to ensure that the interpreter used is portable. The Python +launcher for Windows supports most common forms of POSIX ``#!`` line, but there +are other issues to consider: + +* If you use "/usr/bin/env python" (or other forms of the "python" command, + such as "/usr/bin/python"), you need to consider that your users may have + either Python 2 or Python 3 as their default, and write your code to work + under both versions. +* If you use an explicit version, for example "/usr/bin/env python3" your + application will not work for users who do not have that version. (This + may be what you want if you have not made your code Python 2 compatible). +* There is no way to say "python X.Y or later", so be careful of using an + exact version like "/usr/bin/env python3.4" as you will need to change your + shebang line for users of Python 3.5, for example. + +The Python Zip Application Archive Format +----------------------------------------- + +Python has been able to execute zip files which contain a ``__main__.py`` file +since version 2.6. In order to be executed by Python, an application archive +simply has to be a standard zip file containing a ``__main__.py`` file which +will be run as the entry point for the application. As usual for any Python +script, the parent of the script (in this case the zip file) will be placed on +:data:`sys.path` and thus further modules can be imported from the zip file. + +The zip file format allows arbitrary data to be prepended to a zip file. The +zip application format uses this ability to prepend a standard POSIX "shebang" +line to the file (``#!/path/to/interpreter``). + +Formally, the Python zip application format is therefore: + +1. An optional shebang line, containing the characters ``b'#!'`` followed by an + interpreter name, and then a newline (``b'\n'``) character. The interpreter + name can be anything acceptable to the OS "shebang" processing, or the Python + launcher on Windows. The interpreter should be encoded in UTF-8 on Windows, + and in :func:`sys.getfilesystemencoding()` on POSIX. +2. Standard zipfile data, as generated by the :mod:`zipfile` module. The + zipfile content *must* include a file called ``__main__.py`` (which must be + in the "root" of the zipfile - i.e., it cannot be in a subdirectory). The + zipfile data can be compressed or uncompressed. + +If an application archive has a shebang line, it may have the executable bit set +on POSIX systems, to allow it to be executed directly. + +There is no requirement that the tools in this module are used to create +application archives - the module is a convenience, but archives in the above +format created by any means are acceptable to Python. + |