PEP: 739 Title: Static description file for build details of Python installations Author: Filipe Laíns PEP-Delegate: Paul Moore Discussions-To: https://discuss.python.org/t/pep-739-static-description-file-for-build-details-of-python-installations/44572 Status: Draft Type: Standards Track Topic: Packaging Created: 19-Dec-2023 Python-Version: 3.14 Abstract ======== Introduce a standard format for a static description file with build details of Python installations. Rationale ========= When introspecting a Python installation, running code is often undesirable or impossible. Having a static description file makes various of Python build details available without having to run the interpreter. This is helpful for use-cases such as cross-compilation, Python launchers, etc. Scope ===== This PEP defines a format for the description file, and a standard location for where to place it. Location ======== When possible, Python installations should install the static description file inside the standard library directory, with the name ``build-details.json`` (Eg. ``/usr/lib/python3.14/build-details.json``). .. important:: Given that there may be technical challenges, Python implementations are not required to provide the file if not feasable. In such scenarios, they may choose to provide it in a different maner. .. attention:: Notwithstanding the standard location specified here, it does not prevent the file from **additionally** being provided in another location, and with a different name. In fact, the PEP authors expect future PEPs to define additional locations to install this file, for better discoverability. Format ====== The format specification is defined by the JSON Schema definition provided below, which is rendered in an human-readable format here. .. Rendered with https://gist.github.com/FFY00/eb02d9da2870aae547bc579b7e17a145 .. _spec-start: .. list-table:: :widths: 25 75 * - ``$schema`` - https://json-schema.org/draft/2020-12/schema * - ``$id`` - https://github.com/python/peps/blob/main/peps/pep-0739/python-build-info-v1.0.schema.json * - Title - Static description file for the build details of Python installations * - Type - ``object`` * - Additional properties - **Not allowed** ``schema_version`` ------------------ .. list-table:: :widths: 25 75 * - Type - ``string`` (constant — ``1.0``) * - Description - Schema version. This is a string following the format ``.``, where ```` and ```` are unpaded numbers and represent the **major** and **minor** components of the version. Versions may be arithmetic compared by intrepreting the version string as a decimal number. For this specification version, this value is constant and MUST be ``1.0``. Future versions of this schema MUST use a higher version number. Future versions of this schema MUST NOT use the same **major** version component as other schema version unless its specification is deemed backwards-compatible with them — it can't change, or extend, any parts of the current specification in such a way as the semantics of the interpreted data differ, or that data valid under the new specification is invalid under the older specification, with the exception of additional properties (errors caused by ``additionalProperties``). * - Required - **True** ``base_prefix`` --------------- .. list-table:: :widths: 25 75 * - Type - ``string`` * - Description - Base prefix of the Python installation. Either an absolute path, or a relative path to directory where this file is contained. * - Examples - ``/usr``, ``../..``, etc. * - Required - **False** ``platform`` ------------ .. list-table:: :widths: 25 75 * - Type - ``string`` * - Description - System platform string. This field SHOULD be equivalent to ``sysconfig.get_platform()``. * - Examples - - ``linux-x86_64`` - etc. * - Required - **True** ``language`` ------------ .. list-table:: :widths: 25 75 * - Type - ``object`` * - Description - Object containing details related to the Python language specification. In addition to the required keys, implementations may choose to include extra keys with implementation-specific details. * - Required - **True** * - Additional properties - **Not allowed** ``language.version`` ~~~~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``string`` * - Description - String representation the Python language version — a version string consisting only of the *major* and *minor* components. This field SHOULD be equivalent to ``sysconfig.get_python_version()``. * - Examples - ``3.14``, etc. * - Required - **True** ``language.version_info`` ~~~~~~~~~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``object`` * - Description - Object in the format of :py:data:`sys.version_info`. This section SHOULD be equivalent to :py:data:`sys.version_info`. * - Examples - - ``{'major': 3, 'minor': 14, 'micro': 1, 'releaselevel': 'final', 'serial': 0}`` - etc. * - Required - **False** * - Additional properties - **Not allowed** ``language.version_info.major`` +++++++++++++++++++++++++++++++ .. list-table:: :widths: 25 75 * - Type - ``number`` * - Required - **True** ``language.version_info.minor`` +++++++++++++++++++++++++++++++ .. list-table:: :widths: 25 75 * - Type - ``number`` * - Required - **True** ``language.version_info.micro`` +++++++++++++++++++++++++++++++ .. list-table:: :widths: 25 75 * - Type - ``number`` * - Required - **True** ``language.version_info.releaselevel`` ++++++++++++++++++++++++++++++++++++++ .. list-table:: :widths: 25 75 * - Type - ``string`` (enum — ``alpha``, ``beta``, ``candidate``, ``final``) * - Required - **True** ``language.version_info.serial`` ++++++++++++++++++++++++++++++++ .. list-table:: :widths: 25 75 * - Type - ``number`` * - Required - **True** ``implementation`` ------------------ .. list-table:: :widths: 25 75 * - Type - ``object`` * - Description - Object containing details related to Python implementation. This section SHOULD be equivalent to :py:data:`sys.implementation`. It follows specification defined in PEP 421, meaning that on top of the required keys, implementation-specific keys can also exist, but must be prefixed with an underscore. * - Required - **True** * - Additional properties - **Allowed** ``implementation.name`` ~~~~~~~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``string`` * - Description - Lower-case name of the Python implementation. * - Examples - ``cpython``, ``pypy``, etc. * - Required - **True** ``implementation.version`` ~~~~~~~~~~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``object`` * - Description - Object in the format of :py:data:`sys.version_info`, containing the implementation version. * - Examples - - ``{'major': 3, 'minor': 14, 'micro': 1, 'releaselevel': 'final', 'serial': 0}`` - ``{'major': 7, 'minor': 3, 'micro': 16, 'releaselevel': 'final', 'serial': 0}`` - etc. * - Required - **True** * - Additional properties - **Not allowed** ``implementation.version.major`` ++++++++++++++++++++++++++++++++ .. list-table:: :widths: 25 75 * - Type - ``number`` * - Required - **True** ``implementation.version.minor`` ++++++++++++++++++++++++++++++++ .. list-table:: :widths: 25 75 * - Type - ``number`` * - Required - **True** ``implementation.version.micro`` ++++++++++++++++++++++++++++++++ .. list-table:: :widths: 25 75 * - Type - ``number`` * - Required - **True** ``implementation.version.releaselevel`` +++++++++++++++++++++++++++++++++++++++ .. list-table:: :widths: 25 75 * - Type - ``string`` (enum — ``alpha``, ``beta``, ``candidate``, ``final``) * - Required - **True** ``implementation.version.serial`` +++++++++++++++++++++++++++++++++ .. list-table:: :widths: 25 75 * - Type - ``number`` * - Required - **True** ``interpreter`` --------------- .. list-table:: :widths: 25 75 * - Type - ``object`` * - Description - Object containing details Python interpreter. This section MUST be present if the Python installation provides an interpreter binary, otherwise this section will be missing. * - Required - **False** * - Additional properties - **Not allowed** ``interpreter.path`` ~~~~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``string`` * - Description - The path to the Python interprer. Either an absolute path, or a relative path to the path defined in the ``base_prefix`` key. * - Examples - - ``/usr/bin/python`` - ``bin/python`` - etc. * - Required - **True** ``abi`` ------- .. list-table:: :widths: 25 75 * - Type - ``object`` * - Description - Object containing details related to ABI. * - Required - **False** * - Additional properties - **Not allowed** ``abi.flags`` ~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``array`` * - Description - Build configuration flags, used to calculate the extension suffix. The flags MUST be defined in the order they appear on the extension suffix. * - Examples - ``['t', 'd']``, etc. * - Required - **True** ``abi.extension_suffix`` ~~~~~~~~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``string`` * - Description - Suffix used for extensions built against the current implementation version. This field MUST be present if the Python implementation supports extensions, otherwise this entry will be missing. * - Examples - - ``.cpython-314-x86_64-linux-gnu.so`` - etc. * - Required - **True** ``abi.stable_abi_suffix`` ~~~~~~~~~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``string`` * - Description - Suffix used for extensions built against the stable ABI. This field MUST be present if the Python implementation has a stable ABI extension suffix, otherwise this entry will be missing. * - Examples - ``.abi3.so``, etc. * - Required - **False** ``suffixes`` ------------ .. list-table:: :widths: 25 75 * - Type - ``object`` * - Description - Valid module suffixes grouped by type. This section SHOULD be equivalent to the ``importlib.machinery.*_SUFFIXES`` attributes, if the implementation provides such suffixes. However, if the Python implementation does not provide suffixes of the kind specified by any of the attributes, the equivalent sub-section is not required to be present. Additionally, if a Python implementation provides extension kinds other than the ones listed on ``importlib.machinery`` module, they MAY add a sub-section for them. * - Examples - - ``{'source': ['.py'], 'bytecode': ['.pyc'], 'optimized_bytecode': ['.pyc'], 'debug_bytecode': ['.pyc'], 'extensions': ['.cpython-313-x86_64-linux-gnu.so', '.abi3.so', '.so']}`` - etc. * - Required - **False** * - Additional properties - **Allowed** ``libpython`` ------------- .. list-table:: :widths: 25 75 * - Type - ``object`` * - Description - Object containing details related to the ``libpython`` library. This section MUST by present if Python installation provides a ``libpython`` library, otherwise this section will be missing. * - Required - **False** * - Additional properties - **Not allowed** ``libpython.dynamic`` ~~~~~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``string`` * - Description - The path to the dynamic ``libpython`` library. Either an absolute path, or a relative path to the path defined in the ``base_prefix`` key. This field MUST be present if the Python installation provides a dynamic ``libpython`` library, otherwise this entry will be missing. * - Examples - - ``/usr/lib/libpython3.14.so.1.0`` - ``lib/libpython3.14.so.1.0`` - etc. * - Required - **False** ``libpython.dynamic_stableabi`` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``string`` * - Description - The path to the dynamic ``libpython`` library for the stable ABI. Either an absolute path, or a relative path to the path defined in the ``base_prefix`` key. This field MUST be present if the Python installation provides a dynamic ``libpython`` library, otherwise this entry will be missing. * - Examples - - ``/usr/lib/libpython3.so`` - ``lib/libpython3.so`` - etc. * - Required - **False** ``libpython.static`` ~~~~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``string`` * - Description - The path to the static ``libpython`` library. Either an absolute path, or a relative path to the path defined in the ``base_prefix`` key. This field MUST be present if the Python installation provides a static ``libpython`` library, otherwise this entry will be missing. * - Examples - - ``/usr/lib/python3.14/config-3.14-x86_64-linux-gnu/libpython3.14.a`` - ``lib/python3.14/config-3.14-x86_64-linux-gnu/libpython3.14.a`` - etc. * - Required - **False** ``libpython.link_to_libpython`` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``boolean`` * - Description - Should extensions built against a dynamic ``libpython`` link to it? This field MUST be present if the Python installation provides a dynamic ``libpython`` library, otherwise this entry will be missing. * - Required - **False** ``c_api`` --------- .. list-table:: :widths: 25 75 * - Type - ``object`` * - Description - Object containing details related to the Python C API, if available. This section MUST be present if the Python implementation provides a C API, otherwise this section will be missing. * - Required - **False** * - Additional properties - **Not allowed** ``c_api.headers`` ~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``string`` * - Description - The path to the C API headers. Either an absolute path, or a relative path to the path defined in the ``base_prefix`` key. * - Examples - - ``/usr/include/python3.14`` - ``include/python3.14`` - etc. * - Required - **True** ``c_api.pkgconfig_path`` ~~~~~~~~~~~~~~~~~~~~~~~~ .. list-table:: :widths: 25 75 * - Type - ``string`` * - Description - The path to the pkg-config definition files. Either an absolute path, or a relative path to the path defined in the ``base_prefix`` key. This field MUST be present if the Python implementation provides pkg-config definition files for the C API, otherwise this section will be missing. * - Examples - - ``/usr/lib/pkgconfig`` - ``lib/pkgconfig`` - etc. * - Required - **False** ``arbitrary_data`` ------------------ .. list-table:: :widths: 25 75 * - Type - ``object`` * - Description - Object containing extra arbitrary data. This is meant to be used as an escape-hatch, to include any relevant data that is not covered by this specification. Implamentations may choose what data to provide in this section. * - Required - **False** * - Additional properties - **Allowed** .. _spec-end: Example ======= .. literalinclude:: pep-0739/example.json :language: json :linenos: JSON Schema =========== .. literalinclude:: pep-0739/python-build-info-v1.0.schema.json :language: json :linenos: Rejected Ideas ============== Having a larger scope --------------------- One of the main requests in the discussion of this PEP was the inclusion of other kind of information, such as the ``site-packages`` path. It is the opinion of the PEP authors that information regarding the Python environment should be provided by a separate file, creating the a clear separation between the build details, which should be immutable across any interpreter instance, and details that can change, such as environment details. Copyright ========= This document is placed in the public domain or under the CC0-1.0-Universal license, whichever is more permissive.