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Python Enhancement Proposals

PEP 739 – Static description file for build details of Python installations

Author:
Filipe Laíns <lains at riseup.net>
PEP-Delegate:
Paul Moore <p.f.moore at gmail.com>
Discussions-To:
Discourse thread
Status:
Draft
Type:
Standards Track
Topic:
Packaging
Created:
19-Dec-2023
Python-Version:
3.14
Table of Contents

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.

$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

Type string (constant — 1.0)
Description Schema version.

This is a string following the format <MAJOR>.<MINOR>, where <MAJOR> and <MINOR> 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

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

Type string
Description System platform string.

This field SHOULD be equivalent to sysconfig.get_platform().
Examples
  • linux-x86_64
  • etc.
Required True

language

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

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

Type object
Description Object in the format of sys.version_info.

This section SHOULD be equivalent to 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
Type number
Required True
language.version_info.minor
Type number
Required True
language.version_info.micro
Type number
Required True
language.version_info.releaselevel
Type string (enum — alpha, beta, candidate, final)
Required True
language.version_info.serial
Type number
Required True

implementation

Type object
Description Object containing details related to Python implementation.

This section SHOULD be equivalent to 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

Type string
Description Lower-case name of the Python implementation.
Examples cpython, pypy, etc.
Required True

implementation.version

Type object
Description Object in the format of 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
Type number
Required True
implementation.version.minor
Type number
Required True
implementation.version.micro
Type number
Required True
implementation.version.releaselevel
Type string (enum — alpha, beta, candidate, final)
Required True
implementation.version.serial
Type number
Required True

interpreter

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

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

Type object
Description Object containing details related to ABI.
Required False
Additional properties Not allowed

abi.flags

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

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

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

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

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

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

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

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

c_api

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

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

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

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

Example

 1{
 2  "schema_version": "1.0",
 3  "base_prefix": "/usr",
 4  "platform": "linux-x86_64",
 5  "language": {
 6    "version": "3.14",
 7    "version_info": {
 8      "major": 3,
 9      "minor": 14,
10      "micro": 0,
11      "releaselevel": "alpha",
12      "serial": 0
13    }
14  },
15  "implementation": {
16    "name": "cpython",
17    "version": {
18      "major": 3,
19      "minor": 14,
20      "micro": 0,
21      "releaselevel": "alpha",
22      "serial": 0
23    },
24    "hexversion": 51249312,
25    "cache_tag": "cpython-314",
26    "_multiarch": "x86_64-linux-gnu"
27  },
28  "interpreter": {
29    "path": "/usr/bin/python"
30  },
31  "abi": {
32    "flags": ["t", "d"],
33    "extension_suffix": ".cpython-314-x86_64-linux-gnu.so",
34    "stable_abi_suffix": ".abi3.so"
35  },
36  "suffixes": {
37    "source": [".py"],
38    "bytecode": [".pyc"],
39    "optimized_bytecode": [".pyc"],
40    "debug_bytecode": [".pyc"],
41    "extensions": [".cpython-314-x86_64-linux-gnu.so", ".abi3.so", ".so"]
42  },
43  "libpython": {
44    "dynamic": "/usr/lib/libpython3.14.so.1.0",
45    "dynamic_stableabi": "/usr/lib/libpython3.so",
46    "static": "/usr/lib/python3.14/config-3.14-x86_64-linux-gnu/libpython3.14.a",
47    "link_to_libpython": true
48  },
49  "c_api": {
50    "headers": "/usr/include/python3.14",
51    "pkgconfig_path": "/usr/lib/pkgconfig"
52  }
53}

JSON Schema

  1{
  2  "$schema": "https://json-schema.org/draft/2020-12/schema",
  3  "$id": "https://github.com/python/peps/blob/main/peps/pep-0739/python-build-info-v1.0.schema.json",
  4  "type": "object",
  5  "title": "Static description file for the build details of Python installations",
  6  "required": [
  7    "schema_version",
  8    "platform",
  9    "language",
 10    "implementation"
 11  ],
 12  "additionalProperties": false,
 13  "properties": {
 14    "schema_version": {
 15      "type": "string",
 16      "description": "Schema version.\n\nThis is a string following the format ``<MAJOR>.<MINOR>``, where ``<MAJOR>`` and ``<MINOR>`` 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.\n\nFor this specification version, this value is constant and MUST be ``1.0``.\n\nFuture 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``).",
 17      "const": "1.0"
 18    },
 19    "base_prefix": {
 20      "type": "string",
 21      "description": "Base prefix of the Python installation.\n\nEither an absolute path, or a relative path to directory where this file is contained.",
 22      "examples": [
 23        "/usr",
 24        "../.."
 25      ]
 26    },
 27    "platform": {
 28      "type": "string",
 29      "description": "System platform string.\n\nThis field SHOULD be equivalent to ``sysconfig.get_platform()``.",
 30      "examples": [
 31        "linux-x86_64"
 32      ]
 33    },
 34    "language": {
 35      "type": "object",
 36      "description": "Object containing details related to the Python language specification.\n\nIn addition to the required keys, implementations may choose to include extra keys with implementation-specific details.",
 37      "required": [
 38        "version"
 39      ],
 40      "additionalProperties": false,
 41      "properties": {
 42        "version": {
 43          "type": "string",
 44          "description": "String representation the Python language version — a version string consisting only of the *major* and *minor* components.\n\nThis field SHOULD be equivalent to ``sysconfig.get_python_version()``.",
 45          "examples": ["3.14"]
 46        },
 47        "version_info": {
 48          "type": "object",
 49          "description": "Object in the format of :py:data:`sys.version_info`.\n\nThis section SHOULD be equivalent to :py:data:`sys.version_info`.",
 50          "required": ["major", "minor", "micro", "releaselevel", "serial"],
 51          "additionalProperties": false,
 52          "examples": [
 53            {
 54              "major": 3,
 55              "minor": 14,
 56              "micro": 1,
 57              "releaselevel": "final",
 58              "serial": 0
 59            }
 60          ],
 61          "properties": {
 62            "major": {
 63              "type": "number"
 64            },
 65            "minor": {
 66              "type": "number"
 67            },
 68            "micro": {
 69              "type": "number"
 70            },
 71            "releaselevel": {
 72              "type": "string",
 73              "enum": ["alpha", "beta", "candidate", "final"]
 74            },
 75            "serial": {
 76              "type": "number"
 77            }
 78          }
 79        }
 80      }
 81    },
 82    "implementation": {
 83      "type": "object",
 84      "description": "Object containing details related to Python implementation.\n\nThis 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.",
 85      "required": [
 86        "name",
 87        "version",
 88        "hexversion",
 89        "cache_tag"
 90      ],
 91      "additionalProperties": true,
 92      "properties": {
 93        "name": {
 94          "type": "string",
 95          "description": "Lower-case name of the Python implementation.",
 96          "examples": ["cpython", "pypy"]
 97        },
 98        "version": {
 99          "type": "object",
100          "description": "Object in the format of :py:data:`sys.version_info`, containing the implementation version.",
101          "required": ["major", "minor", "micro", "releaselevel", "serial"],
102          "additionalProperties": false,
103          "examples": [
104            {
105              "major": 3,
106              "minor": 14,
107              "micro": 1,
108              "releaselevel": "final",
109              "serial": 0
110            },
111            {
112              "major": 7,
113              "minor": 3,
114              "micro": 16,
115              "releaselevel": "final",
116              "serial": 0
117            }
118          ],
119          "properties": {
120            "major": {
121              "type": "number"
122            },
123            "minor": {
124              "type": "number"
125            },
126            "micro": {
127              "type": "number"
128            },
129            "releaselevel": {
130              "type": "string",
131              "enum": ["alpha", "beta", "candidate", "final"]
132            },
133            "serial": {
134              "type": "number"
135            }
136          }
137        }
138      }
139    },
140    "interpreter": {
141      "type": "object",
142      "description": "Object containing details Python interpreter.\n\nThis section MUST be present if the Python installation provides an interpreter binary, otherwise this section will be missing.",
143      "required": [
144        "path"
145      ],
146      "additionalProperties": false,
147      "properties": {
148        "path": {
149          "type": "string",
150          "description": "The path to the Python interprer. Either an absolute path, or a relative path to the path defined in the ``base_prefix`` key.",
151          "examples": [
152            "/usr/bin/python",
153            "bin/python"
154          ]
155        }
156      }
157    },
158    "abi": {
159      "type": "object",
160      "description": "Object containing details related to ABI.",
161      "required": [
162        "flags",
163        "extension_suffix"
164      ],
165      "additionalProperties": false,
166      "properties": {
167        "flags": {
168          "type": "array",
169          "description": "Build configuration flags, used to calculate the extension suffix.\n\nThe flags MUST be defined in the order they appear on the extension suffix.",
170          "additionalProperties": true,
171          "examples": [
172            ["t", "d"]
173          ]
174        },
175        "extension_suffix": {
176          "type": "string",
177          "description": "Suffix used for extensions built against the current implementation version.\n\nThis field MUST be present if the Python implementation supports extensions, otherwise this entry will be missing.",
178          "examples": [
179            ".cpython-314-x86_64-linux-gnu.so"
180          ]
181        },
182        "stable_abi_suffix": {
183          "type": "string",
184          "description": "Suffix used for extensions built against the stable ABI.\n\nThis field MUST be present if the Python implementation has a stable ABI extension suffix, otherwise this entry will be missing.",
185          "examples": [
186            ".abi3.so"
187          ]
188        }
189      }
190    },
191    "suffixes": {
192      "type": "object",
193      "description": "Valid module suffixes grouped by type.\n\nThis 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.",
194      "examples": [
195        {
196          "source": [".py"],
197          "bytecode": [".pyc"],
198          "optimized_bytecode": [".pyc"],
199          "debug_bytecode": [".pyc"],
200          "extensions": [".cpython-313-x86_64-linux-gnu.so", ".abi3.so", ".so"]
201        }
202      ]
203    },
204    "libpython": {
205      "type": "object",
206      "description": "Object containing details related to the ``libpython`` library.\n\nThis section MUST by present if Python installation provides a ``libpython`` library, otherwise this section will be missing.",
207      "additionalProperties": false,
208      "properties": {
209        "dynamic": {
210          "type": "string",
211          "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.\n\nThis field MUST be present if the Python installation provides a dynamic ``libpython`` library, otherwise this entry will be missing.",
212          "examples": [
213            "/usr/lib/libpython3.14.so.1.0",
214            "lib/libpython3.14.so.1.0"
215          ]
216        },
217        "dynamic_stableabi": {
218          "type": "string",
219          "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.\n\nThis field MUST be present if the Python installation provides a dynamic ``libpython`` library, otherwise this entry will be missing.",
220          "examples": [
221            "/usr/lib/libpython3.so",
222            "lib/libpython3.so"
223          ]
224        },
225        "static": {
226          "type": "string",
227          "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.\n\nThis field MUST be present if the Python installation provides a static ``libpython`` library, otherwise this entry will be missing.",
228          "examples": [
229            "/usr/lib/python3.14/config-3.14-x86_64-linux-gnu/libpython3.14.a",
230            "lib/python3.14/config-3.14-x86_64-linux-gnu/libpython3.14.a"
231          ]
232        },
233        "link_to_libpython": {
234          "type": "boolean",
235          "description": "Should extensions built against a dynamic ``libpython`` link to it?\n\nThis field MUST be present if the Python installation provides a dynamic ``libpython`` library, otherwise this entry will be missing."
236        }
237      }
238    },
239    "c_api": {
240      "type": "object",
241      "description": "Object containing details related to the Python C API, if available.\n\nThis section MUST be present if the Python implementation provides a C API, otherwise this section will be missing.",
242      "required": [
243        "headers"
244      ],
245      "additionalProperties": false,
246      "properties": {
247        "headers": {
248          "type": "string",
249          "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.",
250          "examples": [
251            "/usr/include/python3.14",
252            "include/python3.14"
253          ]
254        },
255        "pkgconfig_path": {
256          "type": "string",
257          "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.\n\nThis field MUST be present if the Python implementation provides pkg-config definition files for the C API, otherwise this section will be missing.",
258          "examples": [
259            "/usr/lib/pkgconfig",
260            "lib/pkgconfig"
261          ]
262        }
263      }
264    },
265    "arbitrary_data": {
266      "type": "object",
267      "description": "Object containing extra arbitrary data.\n\nThis 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.",
268      "additionalProperties": true
269    }
270  }
271}

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.

Source: https://github.com/python/peps/blob/main/peps/pep-0739.rst

Last modified: 2024-11-06 17:11:55 GMT