pyproject RPM macros

====================

These macros allow projects that follow the Python [packaging specifications]

to be packaged as RPMs.

They are still *provisional*: we can make non-backwards-compatible changes to

the API.

Please subscribe to Fedora's [python-devel list] if you use the macros.

They work for:

* traditional Setuptools-based projects that use the `setup.py` file,

* newer Setuptools-based projects that have a `setup.cfg` file,

* general Python projects that use the [PEP 517] `pyproject.toml` file (which allows using any build system, such as setuptools, flit or poetry).

These macros replace `%py3_build` and `%py3_install`, which only work with `setup.py`.

[packaging specifications]: https://packaging.python.org/specifications/

[python-devel list]: https://lists.fedoraproject.org/archives/list/python-devel@lists.fedoraproject.org/

Usage

-----

To use these macros, first BuildRequire them:

    BuildRequires: pyproject-rpm-macros

Also BuildRequire the devel package for the Python you are building against.

In Fedora, that's `python3-devel`.

(In the future, we plan to make `python3-devel` itself require

`pyproject-rpm-macros`.)

Next, you need to generate more build dependencies (of your projects and

the macros themselves) by running `%pyproject_buildrequires` in the

`%generate_buildrequires` section:

    %generate_buildrequires

    %pyproject_buildrequires

This will add build dependencies according to [PEP 517] and [PEP 518].

To also add run-time and test-time dependencies, see the section below.

If you need more dependencies, such as non-Python libraries, BuildRequire

them manually.

Note that `%generate_buildrequires` may produce error messages `(exit 11)` in

the build log. This is expected behavior of BuildRequires generators; see

[the Fedora change] for details.

[the Fedora change]: https://fedoraproject.org/wiki/Changes/DynamicBuildRequires

Then, build a wheel in `%build` with `%pyproject_wheel`:

    %build

    %pyproject_wheel

And install the wheel in `%install` with `%pyproject_install`:

    %install

    %pyproject_install

`%pyproject_install` installs all wheels in `pyproject-wheeldir/` located in the root of the source tree.

Adding run-time and test-time dependencies

------------------------------------------

To run tests in the `%check` section, the package's runtime dependencies

often need to also be included as build requirements.

This can be done using the `-r` flag:

    %generate_buildrequires

    %pyproject_buildrequires -r

For this to work, the project's build system must support the

[`prepare-metadata-for-build-wheel` hook](https://www.python.org/dev/peps/pep-0517/#prepare-metadata-for-build-wheel).

The popular buildsystems (setuptools, flit, poetry) do support it.

For projects that specify test requirements using an [`extra`

provide](https://packaging.python.org/specifications/core-metadata/#provides-extra-multiple-use),

these can be added using the `-x` flag.

Multiple extras can be supplied by repeating the flag or as a comma separated list.

For example, if upstream suggests installing test dependencies with

`pip install mypackage[testing]`, the test deps would be generated by:

    %generate_buildrequires

    %pyproject_buildrequires -x testing

For projects that specify test requirements in their [tox] configuration,

these can be added using the `-t` flag (default tox environment)

or the `-e` flag followed by the tox environment.

The default tox environment (such as `py37` assuming the Fedora's Python version is 3.7)

is available in the `%{toxenv}` macro.

For example, if upstream suggests running the tests on Python 3.7 with `tox -e py37`,

the test deps would be generated by:

    %generate_buildrequires

    %pyproject_buildrequires -t

If upstream uses a custom derived environment, such as `py37-unit`, use:

    %pyproject_buildrequires -e %{toxenv}-unit

Or specify more environments if needed:

    %pyproject_buildrequires -e %{toxenv}-unit,%{toxenv}-integration

The `-e` option redefines `%{toxenv}` for further reuse.

Use `%{default_toxenv}` to get the default value.

The `-t`/`-e` option uses [tox-current-env]'s `--print-deps-to-file` behind the scenes.

If your package specifies some tox plugins in `tox.requires`,

such plugins will be BuildRequired as well.

Not all plugins are guaranteed to play well with [tox-current-env],

in worst case, patch/sed the requirement out from the tox configuration.

Note that both `-x` and `-t` imply `-r`,

because runtime dependencies are always required for testing.

[tox]: https://tox.readthedocs.io/

[tox-current-env]: https://github.com/fedora-python/tox-current-env/

Additionally to generated requirements you can supply multiple file names to `%pyproject_buildrequires` macro.

Dependencies will be loaded from them:

    %pyproject_buildrequires -r requirements/tests.in requirements/docs.in requirements/dev.in

For packages not using build system you can use `-N` to entirely skip automatical

generation of requirements and install requirements only from manually specified files.

`-N` option cannot be used in combination with other options mentioned above

(`-r`, `-e`, `-t`, `-x`).

Running tox based tests

-----------------------

In case you want to run the tests as specified in [tox] configuration,

you must use `%pyproject_buildrequires` with `-t` or `-e` as explained above.

Then, use the `%tox` macro in `%check`:

    %check

    %tox

The macro:

 - Always prepends `$PATH` with `%{buildroot}%{_bindir}`

 - If not defined, sets `$PYTHONPATH` to `%{buildroot}%{python3_sitearch}:%{buildroot}%{python3_sitelib}`

 - If not defined, sets `$TOX_TESTENV_PASSENV` to `*`

 - Runs `tox` with `-q` (quiet), `--recreate` and `--current-env` (from [tox-current-env]) flags

 - Implicitly uses the tox environment name stored in `%{toxenv}` - as overridden by `%pyproject_buildrequires -e`

By using the `-e` flag, you can use a different tox environment(s):

    %check

    %tox

    %if %{with integration_test}

    %tox -e %{default_toxenv}-integration

    %endif

If you wish to provide custom `tox` flags or arguments, add them after `--`:

    %tox -- --flag-for-tox

If you wish to pass custom `posargs` to tox, use another `--`:

    %tox -- --flag-for-tox -- --flag-for-posargs

Or (note the two sequential `--`s):

    %tox -- -- --flag-for-posargs

Generating the %files section

-----------------------------

To generate the list of files in the `%files` section, you can use `%pyproject_save_files` after the `%pyproject_install` macro.

It takes toplevel module names (i.e. the names used with `import` in Python) and stores paths for those modules and metadata for the package (dist-info directory) to a file stored at `%{pyproject_files}`.

For example, if a package provides the modules `requests` and `_requests`, write:

    %install

    %pyproject_install

    %pyproject_save_files requests _requests

To add listed files to the `%files` section, use `%files -f %{pyproject_files}`.

Note that you still need to add any documentation manually (for now).

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

    %doc README.rst

You can use globs in the module names if listing them explicitly would be too tedious:

    %install

    %pyproject_install

    %pyproject_save_files '*requests'

In fully automated environments, you can use the `*` glob to include all modules (put it in single quotes to prevent Shell from expanding it). In Fedora however, you should always use a more specific glob to avoid accidentally packaging unwanted files (for example, a top level module named `test`).

Speaking about automated environments, some files cannot be classified with `%pyproject_save_files`, but it is possible to list all unclassified files by adding a special `+auto` argument.

    %install

    %pyproject_install

    %pyproject_save_files '*' +auto

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

However, in Fedora packages, always list executables explicitly to avoid unintended collisions with other packages or accidental missing executables:

    %install

    %pyproject_install

    %pyproject_save_files requests _requests

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

    %doc README.rst

    %{_bindir}/downloader

`%pyproject_save_files` can automatically mark license files with `%license` macro

and  language (`*.mo`) files with `%lang` macro and appropriate language code.

Only license files declared via [PEP 639] `License-Field` field are detected.

[PEP 639] is still a draft and can be changed in the future.

Note that `%pyproject_save_files` uses data from the [RECORD file](https://www.python.org/dev/peps/pep-0627/).

If you wish to rename, remove or otherwise change the installed files of a package

*after* `%pyproject_install`, `%pyproject_save_files` might break.

If possible, remove/rename such files in `%prep`.

If not possible, avoid using `%pyproject_save_files` or edit/replace `%{pyproject_files}`.

Generating Extras subpackages

-----------------------------

The `%pyproject_extras_subpkg` macro generates simple subpackage(s)

for Python extras.

The macro should be placed after the base package's `%description` to avoid

issues in building the SRPM.

For example, if the `requests` project's metadata defines the extras

`security` and `socks`, the following invocation will generate the subpackage

`python3-requests+security` that provides `python3dist(requests[security])`,

and a similar one for `socks`.

    %pyproject_extras_subpkg -n python3-requests security socks

The macro works like `%python_extras_subpkg`,

except the `-i`/`-f`/`-F` arguments are optional and discouraged.

A filelist written by `%pyproject_install` is used by default.

For more information on `%python_extras_subpkg`, see the [Fedora change].

[Fedora change]: https://fedoraproject.org/wiki/Changes/PythonExtras

These arguments are still required:

* -n: name of the “base” package (e.g. python3-requests)

* Positional arguments: the extra name(s).

  Multiple subpackages are generated when multiple names are provided.

Limitations

-----------

`%pyproject_install` changes shebang lines of every Python script in `%{buildroot}%{_bindir}` to `#!%{__python3} %{py3_shbang_opt}` (`#!/usr/bin/python3 -s`).

Existing Python flags in shebangs are preserved.

For example `#!/usr/bin/python3 -Ru` will be updated to `#!/usr/bin/python3 -sRu`.

Sometimes, this can interfere with tests that run such scripts directly by name,

because in tests we usually rely on `PYTHONPATH` (and `-s` ignores that).

Would this behavior be undesired for any reason,

undefine `%{py3_shbang_opt}` to turn it off.

Some valid Python version specifiers are not supported.

When a dependency is specified via an URL or local path, for example as:

    https://github.com/ActiveState/appdirs/archive/8eacfa312d77aba28d483fbfb6f6fc54099622be.zip

    /some/path/foo-1.2.3.tar.gz

    git+https://github.com/sphinx-doc/sphinx.git@96dbe5e3

The `%pyproject_buildrequires` macro is unable to convert it to an appropriate RPM requirement and will fail.

If the URL contains the `packageName @` prefix as specified in [PEP 508],

the requirement will be generated without a version constraint:

    appdirs@https://github.com/ActiveState/appdirs/archive/8eacfa312d77aba28d483fbfb6f6fc54099622be.zip

    foo@file:///some/path/foo-1.2.3.tar.gz

Will be converted to:

    python3dist(appdirs)

    python3dist(foo)

Alternatively, when an URL requirement parsed from a text file

given as positional argument to `%pyproject_buildrequires`

contains the `#egg=packageName` fragment,

as documented in [pip's documentation]:

    git+https://github.com/sphinx-doc/sphinx.git@96dbe5e3#egg=sphinx

The requirements will be converted to package names without versions, e.g.:

    python3dist(sphinx)

However upstreams usually only use direct URLs for their requirements as workarounds,

so be prepared for problems.

[PEP 508]: https://www.python.org/dev/peps/pep-0508/

[PEP 517]: https://www.python.org/dev/peps/pep-0517/

[PEP 518]: https://www.python.org/dev/peps/pep-0518/

[PEP 639]: https://www.python.org/dev/peps/pep-0639/

[pip's documentation]: https://pip.pypa.io/en/stable/cli/pip_install/#vcs-support

Testing the macros

------------------

This repository has two kinds of tests.

First, there is RPM `%check` section, run when building the `python-rpm-macros`

package.

Then there are CI tests.

There is currently [no way to run Fedora CI tests locally][ci-rfe],

but you can do what the tests do manually using mock.

For each `$PKG.spec` in `tests/`:

  - clean your mock environment:

        mock -r fedora-rawhide-x86_64 clean

  - install the version of `python-rpm-macros` you're testing, e.g.:

        mock -r fedora-rawhide-x86_64 install .../python-rpm-macros-*.noarch.rpm

  - download the sources:

        spectool -g -R $PKG.spec

  - build a SRPM:

        rpmbuild -bs $PKG.spec

  - build in mock, using the path from the command above as `$SRPM`:

        mock -r fedora-rawhide-x86_64 -n -N $SRPM

[ci-rfe]: https://pagure.io/fedora-ci/general/issue/4