Python Packaging Guidelines (original) (raw)

This version of Python Packaging Guidelines is in effect since 2021 and represents a major rewrite and paradigm shift. Not all packages are updated to reflect this. Older guidelines are still being kept up to date, and existing packages MAY use them instead of this document:

| | These guidelines only support current Fedora releases. For older releases (such as in EPEL 8), consult the 201x-era guidelines. | | ------------------------------------------------------------------------------------------------------------------------------------------------------- |

The two Distro-wide guidelines below apply to all software in Fedora that uses Python at build- or run-time.

The rest of the Guidelines apply to packages that ship code that can be imported with Python’s import statement. Specifically, that is all packages that install files under /usr/lib*/python*/.

Except for the two “Distro-wide guidelines”, these Guidelines do not apply to simple one-file scripts or utilities, especially if these are included with software not written in Python. However, if an application (e.g. CLI tool, script or GUI app) needs a more complex Python library, the library SHOULD be packaged as an importable library under these guidelines.

A major goal for Python packaging in Fedora is to_harmonize with the wider Python ecosystem_, that is, the Python Packaging Authority (PyPA) standards and the Python Package Index (PyPI). Packagers SHOULD be prepared to get involved with upstream projects to establish best practices as outlined here. We wish to improve both Fedora and the wider Python ecosystem.

| | Some build tools (like CMake or autotools) may not work with the latest PyPA standards yet. (For example, they might generate .egg-info directories rather than .dist-info.) While this document’s normative points (MUST/SHOULD) are tool-agnostic, many of the practical tips and helper macros will not be applicable. If this affects you, consider contacting thePython SIGfor guidance and/or following the older guidelinesfor the time being. | | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

| | Fedora’s Python SIG not only develops these guidelines, but it’s also involved in PyPA standards and Python packaging best practices. Check out the wiki ormailing listif you need help or wish to help out. | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

Distro-wide guidelines

Build-time dependency on python3-devel

Every package that uses Python (at run-time and/or build-time) and/or installs Python modulesMUST have a build-time dependency on python3-devel, even if Python is not actually invoked during build-time. Such a package MUST use one of the following in its .spec file:

Only having a transitive build-time dependency on python3-devel is not sufficient. If the package uses an alternate Python interpreter instead of python3(e.g. pypy, jython, python2.7), it MAY instead require the corresponding *-devel package.

The *-devel package brings in relevant RPM macros. It may also enable automated or manual checks: for example, Python maintainers use this requirement to list packages that use Python in some way and might be affected by planned changes.

Mandatory macros

The following macros MUST be used where applicable.

The expansions in parentheses are provided only as reference/examples.

The macros are defined for you in all supported Fedora and EPEL versions.

The rest of this document uses these macros, along with %{_bindir} (/usr/bin/), instead of the raw path names.

Python implementation support

Fedora primarily targets CPython, the reference implementation of the Python language. We generally use “Python” to mean CPython.

Alternate implementations like pypy are available, but currently lack comprehensive tooling and guidelines for packaging. When targetting these, there are no hard rules (except the general Fedora packaging guidelines). But please try to abide by the spirit of these guidelines. When in doubt, consider consulting the Python SIG.

Python version support

Fedora packages MUST NOT depend on other versions of the CPython interpreter than the current python3.

In Fedora, Python libraries are packaged for a single version of Python, called python3. For example, in Fedora 32, python3 is Python 3.8.

In the past, there were multiple Python stacks, e.g. python3.7 and python2.7, installable together on the same machine. That is also the case in some projects that build on top of Fedora, like RHEL, EPEL and CentOS. Fedora might re-introduce parallell-installable stacks in the future (for example if a switch to a new Python version needs a transition period, or if enough interested maintainers somehow appear).

Fedora does include alternate interpreter versions, e.g. python2.7 or python3.5, but these are meant only for developers that need to test upstream code. Bug and security fixes for these interpreters only cover this use case. Packages such as pip or tox, which enable setting up isolated environments and installing third-party packages into them,MAY, as an exception to the rule above, use these interpreters as long as this is coordinated with the maintainers of the relevant Python interpreter.

Naming

Python packages have several different names, which should be kept in sync but will sometimes differ for historical or practical reasons. They are:

Some examples (both good and worse):

Fedora component Built RPM Project name Importable module
python-requests python3-requests requests requests
python-django python3-django Django django
PyYAML python3-pyyaml pyyaml yaml
python-ldap python3-ldap python-ldap ldap, ldif, etc.
python-pillow python3-pillow pillow PIL
python-jupyter-client python3-jupyter-client jupyter-client jupyter_client

Elsewhere in this text, the metavariables SRPMNAME, RPMNAME, PROJECTNAME, MODNAMErefer to these names, respectively.

Canonical project name

Most of these names are case-sensitive machine-friendly identifiers, but the project name has human-friendly semantics: it is case-insensitive and treats some sets of characters (like ._-) specially. For automated use, it needs to be normalized to a canonical format used by Python tools and services such as setuptools, pip and PyPI. For example, the canonical name of the Django project is django (in lowercase). This normalization is defined inPEP 503, and the %{py_dist_name} macro implements it for Fedora packaging. The canonical name is obtained by switching the project name to lower case and converting all runs of non-alphanumeric characters to single “-” characters. Example: “The $ Tree” becomes “the-tree”.

Elsewhere in this text, the metavariable DISTNAME refers to the canonical form of the project name.

Note that in some places, the original, non-normalized project name must be used. For example, the %pypi_source macro and the %autosetup macro need Django, not django.

Name limitations

The character + in names of built (i.e. non-SRPM) packages that include .dist-info or .egg-info directories is reserved for Extras and MUST NOT be used for any other purpose.

As an exception, + characters MAY appear at the end of such names.

The + character triggers the automatic dependency generator for extras.

Replace any + signs in the upstream name with -. Omit + signs on the beginning of the name. Consider adding Provides for the original name with + characters to make the package easier to find for users.

Library naming

A built (i.e. non-SRPM) package for a Python library MUST be named with the prefix python3-. A source package containing primarily a Python library MUST be named with the prefix python-.

The Fedora package’s name SHOULD contain the Canonical project name. If possible, the project name SHOULD be the same as the name of the main importable module, in lowercase, with underscores (_) replaced by dashes (-).

If the importable module name and the project name do not match, users frequently end up confused. In this case, packagers SHOULD ensure that upstream is aware of the problem and (especially for new packages where renaming is feasible) strive to get the package renamed. The Python SIG is available for assistance.

A Python library is a package meant to be imported in Python, such as with import requests. Tools like Ansible or IDLE, whose code is importable but not primarily meant to be imported from other software, are not considered libraries in this sense. So, this section does not apply for them. (See thegeneral Libraries and Applications guidelinesfor general guidance.)

The Fedora component (source package) name for a library should be formed by taking the _canonical project name_and prepending python- if it does not already start with python-. This may leads to conflicts (e.g. between bugzillaand python-bugzilla). In that case, ensure upstream is aware of the potentially confusing naming and apply best judgment.

Application naming

Packages that primarily provide applications, services or any kind of executables SHOULD be named according to the general Fedora naming guidelines(e.g. ansible).

Consider adding a virtual provide according to Library naming above (e.g. python3-PROJECTNAME), if it would help users find the package.

Files to include

Source files and bytecode cache

Packages MUST include the source file (*.py)AND the bytecode cache (*.pyc) for each pure-Python importable module. The source files MUST be included in the same package as the bytecode cache.

Scripts that are not importable (typically ones in %{_bindir} or %{_libexecdir})SHOULD NOT be byte-compiled.

The cache files are found in a __pycache__ directory and have an interpreter-dependent suffix like .cpython-39.pyc.

The cache is not necessary to run the software, but if it is not found, Python will try to create it when a module is imported. If this succeeds, the file is not tracked by RPM and it will linger on the system after uninstallation. If it does not succeed, users can get spurious SELinux AVC denials in the logs.

Normally, byte compilation (generating the cache files) is done for you by the brp-python-bytecompile BRP script, which runs automatically after the %install section of the spec file has been processed. It byte-compiles any .py files that it finds in %{python3_sitelib} or %{python3_sitearch}.

You must include these files of your package (i.e. in the %files section).

If the code is in a subdirectory (importable package), include the entire directory:

%files
%{python3_sitelib}/foo/

Adding the trailing slash is best practice for directories.

However, this cannot be used for top-level modules (those directly in e.g. %{python3_sitelib}), because both %{python3_sitelib} and%{python3_sitelib}/__pycache__/ are owned by Python itself. Here, the%pycached macro can help. It expands to the given *.py source file and its corresponding cache file(s). For example:

%files
%pycached %{python3_sitelib}/foo.py

expands roughly to:

%files
%{python3_sitelib}/foo.py
%{python3_sitelib}/__pycache__/foo.cpython-3X{,.opt-?}.pyc

Manual byte compilation

If you need to bytecompile stuff outside of %{python3_sitelib}/%{python3_sitearch}, use the %py_byte_compile macro.

For example, if your software adds %{_datadir}/mypackage to Python’s import path and imports package foo from there, you will need to compile foo with:

%py_byte_compile %{python3} %{buildroot}%{_datadir}/mypackage/foo/

Dist-info metadata

The metadata SHOULD be included in the same subpackage as the main importable module, if there is one.

This applies to libraries (e.g. python-requests) as well as tools (e.g. ansible).

When software is split into several subpackages, it is OK to only ship metadata in one built RPM. In this case, consider working with upstream to also split the upstream project.

The metadata takes the form of a .dist-info directory installed in %{python3_sitelib} or %{python3_sitearch}, and contains information that tools likeimportlib.metadatause to introspect installed libraries.

For example, a project named MyLib with importable package mylibcould be packaged with:

%files -p python3-mylib
%{python3_sitelib}/mylib/
%{python3_sitelib}/MyLib-%{version}.dist-info/
%doc README.md
%license LICENSE.txt

Note that some older tools instead put metadata in an .egg-info directory, or even a single file. This won’t happen if you use the %pyproject_wheel macro. If your package uses a build system that generates an .egg-info directory or file, please contact Python SIG.

As an exception, the Python standard library MAY ship without this metadata.

Explicit lists

Packages MUST NOT own shared directories owned by Python itself, such as the top-level __pycache__ directories (%{python3_sitelib}/__pycache__, %{python3_sitearch}/__pycache__).

Similarly to the general rule, packagers SHOULD NOT simply glob everything under a shared directory.

In addition to the general list, the following SHOULD NOT be used in %files:

This rule serves as a check against common mistakes which are otherwise hard to detect. It does limit some possibilities for automation.

The most common mistakes this rule prevents are:

PyPI parity

The command pip install PROJECTNAME MUSTinstall the same package (possibly in a different version), install nothing, or fail with a reasonable error message.

If this is not the case, the packager SHOULD contact upstream about this. The goal is to get the project name registered or blocked on PyPI, or to otherwise ensure the rule is followed.

If your package is not or cannot be published on PyPI, you can:

| | Project names that were in Fedora but not on PyPI when these guidelines were proposed are blocked from being uploaded to PyPI. This prevents potential trolls from taking them, but it also blocks legitimate owners. If your package is affected, contact the Python SIG orfile a PyPA issueand mention @encukou. | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |

If your package’s project name conflicts with a different package on PyPI, change the project name. As painful as it is, we need to use a single global namespace across the Python ecosystem. Software that is not written specifically for Fedora already expects that project names use the PyPI namespace: for example, if a third-party library identifies a dependency by name, we don’t want that dependency satisfied by an unrelated Fedora package.

Provides and requirements

Provides for importable modules

For any module intended to be used in Python 3 with import MODNAME, the package that includes it SHOULD provide python3-MODNAME, with underscores (_) replaced by dashes (-).

This is of course always the case if the package is named python3-MODNAME. If the subpackage has some other name, then add %py_provides python3-MODNAME explicitly. See the following section to learn about %py_provides.

Automatic python- and python3.X- provides

For any FOO, a package that provides python3-FOO SHOULD use %py_providesor an automatic generator to also provide python-FOOand python3.X-FOO, where X is the minor version of the interpreter.

The provide SHOULD NOT be added manually: if a generator or macro is not used, do not add the python-FOO / python3.X-FOO provides at all.

This is done automatically for package names by a generator. If absolutely necessary, the generator can be disabled by undefining the %__pythonname_provides macro.

For provides that aren’t package names, or (for technical reasons) for packages without files, the generator will not work. For these cases, the following invocation will provide python3-FOO,python-FOO and python3.X-FOO:

Using the generator or macro is important, because the specific form of the provide may change in the future.

Machine-readable provides

Every Python package MUST provide python3dist(DISTNAME) and python3.Xdist(DISTNAME), where X is the minor version of the interpreter and DISTNAME is the Canonical project namecorresponding to the Dist-info metadata. For example, python3-django would providepython3dist(django) and python3.9dist(django).

This is generated automatically from the dist-info metadata. The provide SHOULD NOT be added manually: if the generator fails to add it, the metadata MUST be fixed.

These Provides are used for automatically generated Requires.

If absolutely necessary, the automatic generator can be disabled by undefining the%{?__pythondist_provides} macro. Consider discussing your use case with the Python SIG if you need to do this.

Dependencies

As mentioned above, each Python package MUST explicitly BuildRequire python3-devel.

Packages MUST NOT have dependencies (either build-time or runtime) with the unversioned prefix python-if the corresponding python3- dependency can be used instead.

Packages SHOULD NOT have explicit dependencies (either build-time or runtime) with a minor-version prefix such as python3.8- or python3.8dist(. Such dependencies SHOULD instead be automatically generated or a macro should be used to get the version.

Packages SHOULD NOT have an explicit runtime dependency on python3.

Instead of depending on python3, packages have an automatic dependency on python(abi) = 3.Xwhen they install files to %{python3_sitelib} or %{python3_sitearch}, or they have an automatic dependency on /usr/bin/python3if they have executable Python scripts, or they have an automatic dependency on libpython3.X.so.1.0()if they embed Python.

These rules help ensure a smooth upgrade path when python3 is updated in new versions of Fedora.

Automatically generated dependencies

Packages MUST use the automatic Python run-time dependency generator.

Packages SHOULD use the opt-in build-dependency generator if possible.

The packager MUST inspect the generated requires for correctness. All dependencies MUST be resolvable within the targeted Fedora version.

Any necessary changes MUST be done by patches or modifying the source (e.g. with sed), rather than disabling the generator. The resulting change SHOULD be offered to upstream. As an exception, filtering MAY be used for temporary workarounds and bootstrapping.

Dependencies covered by the generators SHOULD NOTbe repeated in the .spec file. (For example, if the generator finds a requests dependency, then Requires: python3-requests is redundant.)

The automatically generated requirements are in the form python3.Xdist(DISTNAME), potentially augmented with version requirements or combined together with rich dependencies. Any .0 suffixes are removed from version numbers to match the behavior of Python tools. (PEP 440 specifies that X.Y and X.Y.0 are treated as equal.)

Note that the generators only cover Python packages. Other dependencies, often C libraries like openssl-devel, must be specified in the .spec file manually.

Where the requirements are specified in the source depends on each project’s build system and preferences. Common locations are pyproject.toml, setup.py, setup.cfg,config.toml.

Run-time dependency generator

The automatic runtime dependency generator uses package metadata (as recorded in installed *.dist-info directories) to determine what the package depends on.

In an emergency, you can opt-out from running the requires generator byadding %{?python_disable_dependency_generator}to the package (usually, just before the main package’s %description).

Build-time dependency generator

The opt-in (but strongly recommended) build-time dependency generator gathers information frompyproject.toml build-system information(with fallback to setuptools) plus a standardizedbuild-system hookto gather further requirements. See the %pyproject_buildrequires macrofor more details.

Note that without the -R flag, the generator will include run-time requirements in BuildRequires. This is useful for running tests and for checking that the dependencies are available in Fedora.

Test dependencies

See the Tests section.

Python extras are a way for Python projects to declare that extra dependencies are required for additional functionality.

For example,requests has several standard dependencies (e.g. urllib3). But it also declares an extra named requests[security], which lists additional dependencies (e.g. cryptography). Unlike RPM subpackages, extras can only specify additional dependencies, not additional files. The main package will work if the optional dependency is not installed, but it might have limited functionality.

Python tools treat extras as virtual packages. For example, if a user runs pip install 'requests[security]', or installs a project that depends on requests[security], both requests and cryptography will be installed.

In Fedora, extras are usually provided by packages with no files. Instead of square brackets, Fedora package names conventionally use the + character (which is valid in RPM package names, but not in Python canonical project names nor in extras identifiers).

Handling extras

Python packages SHOULD have Provides for all extras the upstream project specifies, except:

A package that provides a Python extraMUST provide python3dist(DISTNAME[EXTRA]) and python3.Xdist(DISTNAME[EXTRA]), where X is the minor version of the interpreter,DISTNAME is the Canonical project name, and EXTRA is the name of a single extra. For example, python3.9dist(requests[security]). These requirements SHOULD be generated using the automatic dependency generator.

A package that provides a Python extraMUST require the extra’s main package with exact NEVR.

A subpackage that primarily provides one Python extra SHOULD be named by appending + and the extra name to the main package name. For example, python3-requests+security.

The most straightforward way to provide an extra is with a dedicated subpackage containing no files (a “metapackage”). This case can be automated with the %pyproject_extras_subpkg macroor the %python_extras_subpkg macro.

This is not the only way: when some extra is always useful in a distro, it can be provided by the main package; when several extras are related, they may be provided by a single subpackage. However, having one dedicated subpackage per extra allows you to use the automatic dependency generator to ensure that the extras’ requirements will stay in sync with upstream. If you create a dedicated subpackage and want it to be always/usually installed, you can Require/Recommend/Suggest it from the main package.

The dependency generator for extras activates if the following holds:

Example and convenience macros

The extra subpackage for setuptools_scm[toml] can be specified using the %pyproject_extras_subpkg convenience macro as follows. The macro takes the main package name and name(s) of the extra(s):

%pyproject_extras_subpkg -n python3-setuptools_scm toml

If not using %pyproject_install, you will instead need to use %python_extras_subpkgand pass a path to the dist-info directory:

%python_extras_subpkg -n python3-setuptools_scm -i %{python3_sitelib}/*.dist-info toml

For this case, the extras dependency generator will read upstream metadata from the .dist-info directory. If it finds that the extra requires on toml, it will generate Requires: python3.Xdist(toml)and Provides: python3dist(setuptools-scm[toml])(and the corresponding python3.Xdist provide).

If you need additional features that the *_extras_subpkg macros do not cover, you will need to write the subpackage sections manually. Such features can be, for example:

As an example of what you need to write in these cases, both of the *_extras_subpkg macro invocations above expand to the following:

%package -n python3-setuptools_scm+toml
Summary: Metapackage for python3-setuptools_scm: toml extra
Requires: python3-setuptools_scm = %{?epoch:%{epoch}:}%{version}-%{release}

%description -n python3-setuptools_scm+toml
This is a metapackage bringing in toml extra requires for python3-setuptools_scm.
It contains no code, just makes sure the dependencies are installed.

%files -n python3-setuptools_scm+toml
%ghost %{python3_sitelib}/*.dist-info

Note that the dependency generator does not add a dependency on the main package (the Requires: python3-setuptools_scm = ... above). If you are not using the %python_extras_subpkg macro, you need to add it manually.

If an existing extra is removed from an upstream project, the Fedora maintainer SHOULD try to convince upstream to re-introduce it (with an empty list of dependencies). If that fails, the extra SHOULD be Obsoleted from either the main package or another extras subpackage.

Note that removing extras is discouraged insetuptools documentation(see the Tip box near the end of the Optional dependencies section).

The automatic Run-time dependency generatorwill generate Requires on python3.Xdist(DISTNAME[EXTRA])from upstream Requires-Dist metadata.

If the required package does not yet provide metadata for the extra, contact the Fedora maintainer to add it.

In an emergency, you can define the %_python_no_extras_requires macroto avoid automatically generating all extras requirements.

Interpreter invocation

Shebangs

Shebang lines to invoke Python MUST use %{python3} as the interpreter.

Shebang lines to invoke Python SHOULD be #!%{python3} -%{py3_shebang_flags}and they MAY include extra flags.

If (some of) the default flags fromthe %{py3_shebang_flags} macro are not desirable, packages SHOULD explicitly redefine the macro to remove them by undefining the relevant %{_py3_shebang_...} macro.

Using #!%{python3} (#!/usr/bin/python3) rather than e.g. #!/usr/bin/env pythonensures that the system-wide Python interpreter is used to run the code, even if the user modifies $PATH (e.g. by activating a virtual environment).

By default, -%{py3_shebang_flags} expands to -sP(or just -s on Python version lower than 3.11 and Fedora Linux older than 37).

The -s flag, stored in the %{_py3_shebang_s} macro, means _don’t add user site directory to sys.path._That ensures the user’s Python packages (e.g. installed by pip install --user, or just placed in the current directory) don’t interfere with the RPM installed software. Sometimes, such content is desirable, such as with plugins.

The -P flag, stored in the %{_py3_shebang_P} macro, means _don’t add the script’s directory to sys.path._Sometimes, adding the script’s directory to sys.path is desirable, such as with executable Python scripts installed in a custom directory, importing each other.

Removing the undesired flag(s) from the %{py3_shebang_flags} macrorather than not using the macro at all, ensures that existing or future automation won’t add the flag.

# Remove -s from Python shebang - ensure that extensions installed with pip
# to user locations are seen and properly loaded
%undefine _py3_shebang_s
# Don't add -P to Python shebangs
# The executable Python scripts in /usr/share/opt-viewer/ import each other
%undefine _py3_shebang_P

The %pyproject_install macroautomatically changes all Python shebangs in %{buildroot}%{_bindir}/* to use %{python3}and add contents of the %{py3_shebang_flags} macroto the existing flags. If you’re not using that macro or you need to change a shebang in a different directory, you can use the %py3_shebang_fix macro as follows:

%py3_shebang_fix SCRIPTNAME …

Invokable Python modules

Every executable TOOLfor which the current version of Python mattersSHOULD also be invokable by python3 -m TOOL.

If the software doesn’t provide this functionality, packagers SHOULD ask the upstream to add it.

This applies to tools that modify the current Python environment (like installing or querying packages), use Python for configuration, or use Python to run plugins. It does not apply to tools like GIMP or Bash which support plugins in multiple languages and/or have other means to specify the interpreter.

For example, pip can be invoked as python3 -m pip.

This allows users to accurately specify the Python version used to run the software. This convention works across different environments that might not always set $PATH or install scripts consistently.

Using Cython

Tightening thegeneral Fedora policy, packages MUST NOT use files pre-generated by Cython. These MUST be deleted in %prep and regenerated during the build.

As an exception, these sources MAY be used temporarily to prevent build time circular dependencies by following thebootstrapping guidelines.

Generated files (the ones that must be deleted) have a generic .c or .cpp extension. Cython source files (which should stay) usually have the .pyx or .pxd extension.

Cython is a popular tool for writing extension modules for Python. If compiles a Python-like language to C, which is then fed to the C compiler. Historically, Cython was hard to use upstream as a build-time dependency. Many projects include pre-generated C files in source distributions to avoid users from needing to install the tool.

Cython uses CPython’s fast-changing internal API for performance reasons. For a new release of Python, Cython generally needs to be updated and the C files regenerated. In Fedora, this is frequently needed before upstreams release re-generated sources (e.g. for Alpha versins of Python). Since we do not have a problem with build-time dependencies, we always want to run the Cython step.

For example, PyYAML removes a generated C file with:

For another example, in python-lxml all C files are generated with Cython, which allows removing them with:

# Remove pregenerated Cython C sources
find -type f -name '*.c' -print -delete

Some upstreams mix generated and hand-written C files. In such cases a grep like this one from scipy helps (but might not be entirely future proof):

# Remove pregenerated Cython C sources
rm $(grep -rl '/\* Generated by Cython')

Tests

Running tests

If a test suite exists upstream, it SHOULD be run in the %check section. If that is not possible with reasonable effort, at least a basic smoke test (such as importing the packaged module)MUST be run in %check.

You MAY exclude specific failing tests. You MUST NOT disable the entire testsuite or ignore its result to solve a build failure.

As an exception, you MAY disable tests with an appropriate %if conditional (e.g. bcond) when bootstrapping.

Most errors in Python happen at run-time, so tests are extremely important to root out issues, especially when mass rebuilds are required.

Common reasons for skipping tests in %check include requiring network access, dependencies not packaged in Fedora, and/or specialized hardware or resources.

In these cases, you can use the %pyproject_check_importor the %py3_check_import macroto test that installed modules are importable.

Tox

A popular testing tool, and one which is well integrated in Fedora, is tox. Upstream, it is commonly used to test against multiple Python versions. In a Fedora package, BuildRequire test dependencies via %pyproject_buildrequires -t or -e(see Test dependencies below) and run tox with:

This sets up the environment ($PATH, $PYTHONPATH, $TOX_TESTENV_PASSENV) and instructs tox to use the current environment rather than create new ones. For more options, see Build macros.

pytest

When upstream doesn’t use tox, the tests need to be run directly depending on upstream choice of a test runner. A popular runner is pytest, which can be invoked using %pytest.

Use positional arguments to specify the test directory. See python3 -m pytest --help for how to select tests. For example, if network-related tests are marked “network”, you might use -m to deselect them:

The %pytest macro sets several environment variables appropriate for %check:

Other test runners

If upstream doesn’t use tox or pytest, other test runners can be invoked with the %{py3_test_envvars} macro, available since Fedora Linux 38.

This macro sets several environment variables similarly to %pytest, but requires the actual test runner to be invoked after the macro, for example:

%{py3_test_envvars} %{python3} -m unittest

Or:

%{py3_test_envvars} %{python3} tests/run_tests.py

Test dependencies

One part of the Python packaging ecosystem that is still not standardized is specifying test dependencies (and development dependencies in general).

A good, common way for upstreams to specify test dependencies is using an extra like [test], [testing] or [dev]. In this case, upstream’s instructions to install test dependencies might look like $ pip install -e.[test].

Another way to specify test dependencies is using a dedicated dependency group (PEP 735).

Projects using tox usually specify test dependencies in a tox-specific format: a requireskey in the configuration.

These three forms are handled by the %pyproject_buildrequires macro.

If upstream does not use either form, list test dependencies as manual BuildRequires in the spec file, for example:

# Test dependencies:
BuildRequires: python3dist(pytest)

If you need to do this, consider asking upstream to add a [test] extra or a test dependency group.

Linters

In %check, packages SHOULD NOT run “linters”: code style checkers, test coverage checkers and other tools that check code quality rather than functionality.

Tools like black, pylint, flake8, or mypyare often “opinionated” and their “opinions” change frequently enough that they are nuisance in Fedora, where the linter is not pinned to an exact version. Furthermore, some of these tools take a long time to adapt to new Python versions, preventing early testing with Alpha and Beta releases of Python. And they are just not needed: wrongly formatted code is not important enough for the Fedora packager to bug the upstream about it. Making such an issue break a package build is entirely unreasonable.

Linters do make sense in upstream CI. But not in Fedora.

If a linter is used, disable it and remove the dependency on it. If that is not easy, talk to upstream about making it easy (for example with a configuration option or a separate tox environment).

For packages that contain such linters, use them at runtime or extend them, you will usually need to run the linter in %check. Run it to test functionality, not code quality of the packaged software.

Source files from PyPI

Packages MAY use sources from PyPI.

However, packages SHOULD NOT use an archive that omits test suites, licenses and/or documentation present in other source archives.

For example, as of this writing pip provides asource tarball (“sdist”)which omits the relatively large tests and docs directories present in the source on GitHub. In this case, the tarball from GitHub should be used. (See the Git tags section of Fedora SourceURL guidelines.)

When using sources from PyPI, you can use the the %pypi_source macroto generate the proper URL.

| | Some Python packages use metadata from git(or a similar version control system) to construct their version string, for example via setuptools_scm. When publishing a package to PyPI, this version metadata is usually stored and included in a file, so the version control history is no longer needed to construct it. However, when using tarballs from a git forge directly, this version information is missing and must be manually provided by the packager. For example, the SETUPTOOLS_SCM_PRETEND_VERSION environment variable can be set to the desired value in the %generate_buildrequires and %build scripts in the spec file for packages that use setuptools_scm for this purpose. | | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

Example spec file

The following is a viable spec file for a Python library called Pellothat follows packaging best practices.

Note that the project name Pello normalizesto the lowercase pello. The example spec shows where each variant is typically used.

The project has an extra color, which enables colorized output when installed. Since the required dependency is quite minimal and color improves the user experience, the extra is Recommended from the main package.

Name:           python-pello
Version:        1.0.4
Release:        1%{?dist}
Summary:        Example Python library

License:        MIT-0
URL:            https://github.com/fedora-python/Pello
Source:         %{url}/archive/v%{version}/Pello-%{version}.tar.gz

BuildArch:      noarch
BuildRequires:  python3-devel

%global _description %{expand:
A python module which provides a convenient example.
This description provides some details.}

%description %_description

%package -n python3-pello
Summary:        %{summary}
Recommends:     python3-pello+color

%description -n python3-pello %_description


%pyproject_extras_subpkg -n python3-pello color

%prep
%autosetup -p1 -n Pello-%{version}


%generate_buildrequires
%pyproject_buildrequires -t


%build
%pyproject_wheel


%install
%pyproject_install

# Here, "pello" is the name of the importable module.
%pyproject_save_files -l pello


%check
%tox


# Note that there is no %%files section for
# the unversioned python module, python-pello.

# For python3-pello, %%{pyproject_files} handles code files and %%license,
# but executables and documentation must be listed in the spec file:

%files -n python3-pello -f %{pyproject_files}
%doc README.md
%{_bindir}/pello_greeting


%changelog

Empty spec file

The following is an unfinished spec file template to copy, paste and edit.

Name:           python-...
Version:        ...
Release:        0%{?dist}
Summary:        ...

License:        ...
URL:            https://...
Source:         %{url}/archive/v%{version}/...-%{version}.tar.gz / %{pypi_source ...}

BuildArch:      noarch / BuildRequires:  gcc
BuildRequires:  python3-devel

%global _description %{expand:
...}

%description %_description

%package -n python3-...
Summary:        %{summary}

%description -n python3-... %_description


%prep
%autosetup -p1 -n ...-%{version}


%generate_buildrequires
%pyproject_buildrequires -x... / -g... / -t


%build
%pyproject_wheel


%install
%pyproject_install
%pyproject_save_files ...


%check
%tox / %pytest / %pyproject_check_import ...


%files -n python3-... -f %{pyproject_files}
%doc README.*
%{_bindir}/...


%changelog

Macro Reference

This section documents macros that are available to help with Python packaging. The expansions in parentheses are provided only as reference/examples.

See the Mandatory macros section above for:

Shebang macros

Convenience macros

Build macros

The “pyproject macros” are most useful for packaging Python projects that use the pyproject.toml file defined in PEP 518and PEP 517, which specifies the package’s build dependencies (including the build system, such as setuptools, flit or poetry).

If pyproject.toml is not found, the macros automatically fall backs to using setuptoolswith configuration in setup.cfg/setup.py.

A full tutorial and discussion for the macros is available in the macros’README.

%files -n python3-DISTNAME -f %{pyproject_files}

Test macros

%check  
%tox %{?with_integration_tests:-e %{toxenv},%{toxenv}-integration}

Flags for the tox command can be specified after --:
Additional arguments for the test runner may be specified after another --: 

 %tox -- --parallel 0 -- --verbose tests/*

Manual generation

The following macros are available for cases where automatic generation is turned off. They can also be useful for handling files in non-standard locations where the generators don’t look.

System Settings

The following macros can be redefined for special use cases.

Comparing Python versions

When comparing Python versions (e.g. to ask: is %{python3_version} greater than 3.8?), using naïve %if %{python3_version} > 3.8or %if "%{python3_version}" > "3.8" is not possible, because the comparison is performed alphabetically on strings. Hence it is true that "3.10" < "3.8" (which is not desired).

It is possible to explicitly compare version literals by using the v prefix, similar to the Python string prefixes:

%if v"0%{?python3_version}" > v"3.8"
...
%endif

| | As a workaround for compatibility with RPM releases up to 4.16 (EPEL 9),%{python3_version_nodots} can be compared as an integers: %if 0%{?python3_version_nodots} > 39 ... %endif This will work with Python 3.10 (310 > 39), but eventually break with Python 4.0 (40 < 310). | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

Disabling automation

The following macros can turn off Python-specific automation.

Consider contacting the Python SIG if you need to do this.

Deprecated Macros