PEP 739 – build-details.json
1.0 — a static description file for Python build details
- Author:
- Filipe Laíns <lains at python.org>
- PEP-Delegate:
- Paul Moore <p.f.moore at gmail.com>
- Discussions-To:
- Discourse thread
- Status:
- Accepted
- Type:
- Standards Track
- Topic:
- Packaging
- Created:
- 19-Dec-2023
- Python-Version:
- 3.14
- Resolution:
- Discourse message
Abstract
This PEP introduces build-details.json
, a static description file containing
build details of Python installations.
It includes the definition of version 1.0 of the file format, and defines the standard location for this file.
Rationale
When introspecting a Python installation, running code is often undesirable or impossible. Having a static description file makes various build details of the Python installation available without having to run the interpreter.
This is helpful for use-cases such as cross-compilation, Python launchers, etc.
Scope
build-details.json
is an installation-wide file, meaning that it MUST
only contain information that is constant across all environments of the Python
installation.
Information specific to a Python environment, such as the site-packages
path, is outside the scope for this file, and the PEP authors expect that a
static environment description file will be introduced via a future PEP.
Specification
Starting from Python 3.14, a file named build-details.json
following the
format specified in this PEP, or a future version, MUST be installed in the
platform-independent standard library directory (stdlib
, eg.
/usr/lib/python3.14/build-details.json
), UNLESS unfeasible due to
technical limitations.
Attention
In addition to the standard location specified by this PEP, the
build-details.json
file MAY also be installed into additional
locations, and under a different name. Notwithstanding, the file SHOULD
still be available at the standard location.
In actuality, the PEP authors expect future PEPs to define additional install locations with 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 | build-details.json — a static description file with 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 For this specification version, this value is constant and
MUST be 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 |
Required | True |
base_prefix
Type | string |
Description | Base prefix of the Python installation. Either an absolute path, or a path relative to directory where this file is contained. |
Examples | /usr , ../.. , etc. |
Required | True |
base_interpreter
Type | string |
Description | The path to the Python interpreter of the base installation. Either an absolute path, or a path relative to This field MUST be present if the installation provides an interpreter executable. |
Examples |
|
Required | False |
platform
Type | string |
Description | System platform string. This field SHOULD be equivalent to
|
Examples |
|
Required | True |
language
Type | object |
Description | Object containing details related to the Python language specification. |
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
|
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
|
Examples |
|
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 the Python implementation. This section SHOULD be equivalent to
|
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 |
|
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 |
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 |
|
Required | False |
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 MUST be present if the Python installation
supports importing external files, and it SHOULD be
equivalent to the Additionally, if a Python implementation provides extension
kinds other than the ones listed on |
Examples |
|
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 |
Required | False |
Additional properties | Not allowed |
libpython.dynamic
Type | string |
Description | The path to the dynamic libpython library.Either an absolute path, or a path relative to This field MUST be present if the Python installation
provides a dynamic |
Examples |
|
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 path relative to This field MUST be present if the Python installation
provides a dynamic If this key is present |
Examples |
|
Required | False |
libpython.static
Type | string |
Description | The path to the static libpython library.Either an absolute path, or a path relative to This field MUST be present if the Python installation
provides a static |
Examples |
|
Required | False |
libpython.link_extensions
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 |
Required | False |
c_api
Type | object |
Description | Object containing details related to the Python C API. 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 path relative to |
Examples |
|
Required | True |
c_api.pkgconfig_path
Type | string |
Description | The path to the pkg-config definition files. Either an absolute path, or a path relative to This field MUST be present if the Python implementation provides pkg-config definition files, otherwise this section will be missing. |
Examples |
|
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. Implementations 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 "base_interpreter": "/usr/bin/python",
5 "platform": "linux-x86_64",
6 "language": {
7 "version": "3.14",
8 "version_info": {
9 "major": 3,
10 "minor": 14,
11 "micro": 0,
12 "releaselevel": "alpha",
13 "serial": 0
14 }
15 },
16 "implementation": {
17 "name": "cpython",
18 "version": {
19 "major": 3,
20 "minor": 14,
21 "micro": 0,
22 "releaselevel": "alpha",
23 "serial": 0
24 },
25 "hexversion": 51249312,
26 "cache_tag": "cpython-314",
27 "_multiarch": "x86_64-linux-gnu"
28 },
29 "abi": {
30 "flags": ["t", "d"],
31 "extension_suffix": ".cpython-314-x86_64-linux-gnu.so",
32 "stable_abi_suffix": ".abi3.so"
33 },
34 "suffixes": {
35 "source": [".py"],
36 "bytecode": [".pyc"],
37 "optimized_bytecode": [".pyc"],
38 "debug_bytecode": [".pyc"],
39 "extensions": [".cpython-314-x86_64-linux-gnu.so", ".abi3.so", ".so"]
40 },
41 "libpython": {
42 "dynamic": "/usr/lib/libpython3.14.so.1.0",
43 "dynamic_stableabi": "/usr/lib/libpython3.so",
44 "static": "/usr/lib/python3.14/config-3.14-x86_64-linux-gnu/libpython3.14.a",
45 "link_extensions": true
46 },
47 "c_api": {
48 "headers": "/usr/include/python3.14",
49 "pkgconfig_path": "/usr/lib/pkgconfig"
50 }
51}
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": "build-details.json — a static description file with build details of Python installations",
6 "required": [
7 "schema_version",
8 "base_prefix",
9 "platform",
10 "language",
11 "implementation"
12 ],
13 "additionalProperties": false,
14 "properties": {
15 "schema_version": {
16 "type": "string",
17 "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 arithmetically 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``).",
18 "const": "1.0"
19 },
20 "base_prefix": {
21 "type": "string",
22 "description": "Base prefix of the Python installation.\n\nEither an absolute path, or a path relative to directory where this file is contained.",
23 "examples": [
24 "/usr",
25 "../.."
26 ]
27 },
28 "base_interpreter": {
29 "type": "string",
30 "description": "The path to the Python interprer of the base installation.\n\nEither an absolute path, or a path relative to ``base_prefix``.\n\nThis field **MUST** be present if the installation provides an interpreter executable.",
31 "examples": [
32 "/usr/bin/python",
33 "bin/python"
34 ]
35 },
36 "platform": {
37 "type": "string",
38 "description": "System platform string.\n\nThis field **SHOULD** be equivalent to ``sysconfig.get_platform()``.",
39 "examples": [
40 "linux-x86_64"
41 ]
42 },
43 "language": {
44 "type": "object",
45 "description": "Object containing details related to the Python language specification.",
46 "required": [
47 "version"
48 ],
49 "additionalProperties": false,
50 "properties": {
51 "version": {
52 "type": "string",
53 "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()``.",
54 "examples": ["3.14"]
55 },
56 "version_info": {
57 "type": "object",
58 "description": "Object in the format of :py:data:`sys.version_info`.\n\nThis section **SHOULD** be equivalent to :py:data:`sys.version_info`.",
59 "required": ["major", "minor", "micro", "releaselevel", "serial"],
60 "additionalProperties": false,
61 "examples": [
62 {
63 "major": 3,
64 "minor": 14,
65 "micro": 1,
66 "releaselevel": "final",
67 "serial": 0
68 }
69 ],
70 "properties": {
71 "major": {
72 "type": "number"
73 },
74 "minor": {
75 "type": "number"
76 },
77 "micro": {
78 "type": "number"
79 },
80 "releaselevel": {
81 "type": "string",
82 "enum": ["alpha", "beta", "candidate", "final"]
83 },
84 "serial": {
85 "type": "number"
86 }
87 }
88 }
89 }
90 },
91 "implementation": {
92 "type": "object",
93 "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.",
94 "required": [
95 "name",
96 "version",
97 "hexversion",
98 "cache_tag"
99 ],
100 "additionalProperties": true,
101 "properties": {
102 "name": {
103 "type": "string",
104 "description": "Lower-case name of the Python implementation.",
105 "examples": ["cpython", "pypy"]
106 },
107 "version": {
108 "type": "object",
109 "description": "Object in the format of :py:data:`sys.version_info`, containing the implementation version.",
110 "required": ["major", "minor", "micro", "releaselevel", "serial"],
111 "additionalProperties": false,
112 "examples": [
113 {
114 "major": 3,
115 "minor": 14,
116 "micro": 1,
117 "releaselevel": "final",
118 "serial": 0
119 },
120 {
121 "major": 7,
122 "minor": 3,
123 "micro": 16,
124 "releaselevel": "final",
125 "serial": 0
126 }
127 ],
128 "properties": {
129 "major": {
130 "type": "number"
131 },
132 "minor": {
133 "type": "number"
134 },
135 "micro": {
136 "type": "number"
137 },
138 "releaselevel": {
139 "type": "string",
140 "enum": ["alpha", "beta", "candidate", "final"]
141 },
142 "serial": {
143 "type": "number"
144 }
145 }
146 }
147 }
148 },
149 "abi": {
150 "type": "object",
151 "description": "Object containing details related to ABI.",
152 "required": [
153 "flags"
154 ],
155 "additionalProperties": false,
156 "properties": {
157 "flags": {
158 "type": "array",
159 "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.",
160 "additionalProperties": true,
161 "examples": [
162 ["t", "d"]
163 ]
164 },
165 "extension_suffix": {
166 "type": "string",
167 "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.",
168 "examples": [
169 ".cpython-314-x86_64-linux-gnu.so"
170 ]
171 },
172 "stable_abi_suffix": {
173 "type": "string",
174 "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.",
175 "examples": [
176 ".abi3.so"
177 ]
178 }
179 }
180 },
181 "suffixes": {
182 "type": "object",
183 "description": "Valid module suffixes grouped by type.\n\nThis section **MUST** be present if the Python installation supports importing external files, and it **SHOULD** be equivalent to the ``importlib.machinery.*_SUFFIXES`` attributes.\n\nAdditionally, if a Python implementation provides extension kinds other than the ones listed on ``importlib.machinery`` module, they **MAY** add a sub-section for them.",
184 "examples": [
185 {
186 "source": [".py"],
187 "bytecode": [".pyc"],
188 "optimized_bytecode": [".pyc"],
189 "debug_bytecode": [".pyc"],
190 "extensions": [".cpython-313-x86_64-linux-gnu.so", ".abi3.so", ".so"]
191 }
192 ]
193 },
194 "libpython": {
195 "type": "object",
196 "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.",
197 "additionalProperties": false,
198 "properties": {
199 "dynamic": {
200 "type": "string",
201 "description": "The path to the dynamic ``libpython`` library.\n\nEither an absolute path, or a path relative to ``base_prefix``.\n\nThis field **MUST** be present if the Python installation provides a dynamic ``libpython`` library, otherwise this entry will be missing.",
202 "examples": [
203 "/usr/lib/libpython3.14.so.1.0",
204 "lib/libpython3.14.so.1.0"
205 ]
206 },
207 "dynamic_stableabi": {
208 "type": "string",
209 "description": "The path to the dynamic ``libpython`` library for the stable ABI.\n\nEither an absolute path, or a path relative to ``base_prefix``.\n\nThis field **MUST** be present if the Python installation provides a dynamic ``libpython`` library targetting the Stable ABI, otherwise this entry will be missing.\n\nIf this key is present ``dynamic`` **MUST** also be set.",
210 "examples": [
211 "/usr/lib/libpython3.so",
212 "lib/libpython3.so"
213 ]
214 },
215 "static": {
216 "type": "string",
217 "description": "The path to the static ``libpython`` library.\n\nEither an absolute path, or a path relative to ``base_prefix``.\n\nThis field **MUST** be present if the Python installation provides a static ``libpython`` library, otherwise this entry will be missing.",
218 "examples": [
219 "/usr/lib/python3.14/config-3.14-x86_64-linux-gnu/libpython3.14.a",
220 "lib/python3.14/config-3.14-x86_64-linux-gnu/libpython3.14.a"
221 ]
222 },
223 "link_extensions": {
224 "type": "boolean",
225 "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."
226 }
227 }
228 },
229 "c_api": {
230 "type": "object",
231 "description": "Object containing details related to the Python C API.\n\nThis section **MUST** be present if the Python implementation provides a C API, otherwise this section will be missing.",
232 "required": [
233 "headers"
234 ],
235 "additionalProperties": false,
236 "properties": {
237 "headers": {
238 "type": "string",
239 "description": "The path to the C API headers.\n\nEither an absolute path, or a path relative to ``base_prefix``.",
240 "examples": [
241 "/usr/include/python3.14",
242 "include/python3.14"
243 ]
244 },
245 "pkgconfig_path": {
246 "type": "string",
247 "description": "The path to the pkg-config definition files.\n\nEither an absolute path, or a path relative to ``base_prefix``.\n\nThis field **MUST** be present if the Python implementation provides pkg-config definition files, otherwise this section will be missing.",
248 "examples": [
249 "/usr/lib/pkgconfig",
250 "lib/pkgconfig"
251 ]
252 }
253 }
254 },
255 "arbitrary_data": {
256 "type": "object",
257 "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. Implementations may choose what data to provide in this section.",
258 "additionalProperties": true
259 }
260 }
261}
Rejected Ideas
Including environment-specific data
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.
Including environment-specific data in the config file means that it would be environment-specific, so virtual environments would need their own config file. This is problematic because virtual environments survive updates of the base Python installation, creating the possibily for the static config file to be outdated, and making its data unreliable, which defeats its purpose.
The proposed solution, partially implemented in this PEP, is to have a
build-details.json
file, referent to the base Python installation, and a
environment.json
file, referent to the specific environment.
With build-details.json
being part of the Python distribution, when the base
Python installation gets updated, build-details.json
does too, ensuring the
static description files are never outdated.
Copyright
This document is placed in the public domain or under the CC0-1.0-Universal license, whichever is more permissive.
Source: https://github.com/python/peps/blob/main/peps/pep-0739.rst
Last modified: 2025-02-07 01:10:57 GMT