pypi2pkgbuild 0.3
A PyPI to PKGBUILD converter.
License: MIT
Requires Python: >=3.7

PyPI2PKGBUILD
=============

|PyPI|

.. |PyPI|
   image:: https://img.shields.io/pypi/v/pypi2pkgbuild.svg
   :target: https://pypi.python.org/pypi/pypi2pkgbuild

Convert PyPI packages to Arch Linux packages, inspired from pip2arch_.

Handles packages of all sizes, from the simplest (pure Python, no dependencies)
to the most complex (C-level dependencies, external C libraries, etc., e.g.
most of the scientific Python stack, or GUI toolkits such as PyGObject and
wxPython) [#]_.

.. [#] ... with a bit of help.

.. contents:: :local:

Dependencies and installation
-----------------------------

``pypi2pkgbuild.py`` depends on the Arch Linux packages namcap_, pkgfile_, and
python-pip_ [#]_.

.. _namcap: https://wiki.archlinux.org/index.php/Namcap
.. _pkgfile: https://wiki.archlinux.org/index.php/Pkgfile
.. _python-pip: https://wiki.archlinux.org/index.php/Python#Package_management

.. [#] Officially, only the latest releases of pacman and pip are supported.
   In practice, the hard requirements that I am aware of are pacman≥5.1
   (which changed the behavior of ``makepkg --printsrcinfo``) and pip≥10
   (which changed the default format of ``pip --list``).

The script can be installed with ``pip install [--user] .``, or can also be run
directly.

One can even run ``pypi2pkgbuild.py`` on itself to create a proper Arch package
(``pypi2pkgbuild.py git+https://github.com/anntzer/pypi2pkgbuild``).

A minimal test suite (checking that ``pypi2pkgbuild.py`` can indeed package
itself) can by run with pytest≥3.9 (``pytest -s`` to keep the output to the
terminal).

Usage
-----

``pypi2pkgbuild.py PYPINAME`` creates a PKGBUILD for the latest version of the
given PyPI package and the current version of the Python interpreter (Python 3
only).  Prereleases are considered if the ``--pre`` flag is passed.  Because
PyPI's dependency information is somewhat unreliable, it installs the package
in a venv to figure out the dependencies.  Note that thanks to ``pip``'s wheel
cache, the build is later reused; i.e. the procedure entails very little extra
work.

A ``-git`` package can be built with ``pypi2pkgbuild.py git+https://...``.

The package is then built and verified with ``namcap``.

The goal is to make this tool as automated as possible: if all the information
to build a package is (reasonably) accessible, this tool should be able to
build it.

In order to provide additional information to ``makepkg``, edit
``PKGBUILD_EXTRAS`` (which can also be done with the ``--pkgbuild-extras``
flag).  This file is sourced at the *end* of ``PKGBUILD``.  For ease of
patching, the ``build``, ``package``, and, where applicable, ``pkgver``
functions are defined by forwarding to ``_build``, ``_package``, and
``_pkgver``.  A ``_check`` function is also available, but not used (due to the
lack of standard testing CLI).  Some useful examples of ``PKGBUILD_EXTRAS`` are
listed in the ``pkgbuild-extras`` directory.

Usage notes
```````````

- It is suggested to create an alias with standard options set, e.g.

.. code-block:: sh

   alias pypi2pkgbuild.py='PKGEXT=.pkg.tar pypi2pkgbuild.py -g cython -b /tmp/pypi2pkgbuild/ -f'

- By default, the ``pkgrel`` of (standard) packages is set to ``00``.  This
  allows automatic upgrading into official packages (and AUR ones, if an AUR
  helper is used) whenever the repositories are updated.  Additionally, the use
  of ``00`` rather than ``0`` serves as a (weak) marker that the package was
  automatically generated by this tool.  In order to prevent such an upgrade,
  one can use the ``--pkgrel`` flag to set ``pkgrel`` to, e.g., ``99``.

- If one wishes to completely bypass AUR Python packages while maintaining the
  use of an AUR helper for non-Python packages, one can define a shell function
  that excludes ``pypi2pkgbuild.py``-generated packages that do not appear in
  the official repositories, e.g., for ``pacaur``:

  .. code-block:: sh

     pacaur() {
        if [[ "$1" = "-Syu" ]]; then
           # Update, in case some packages moved in or out of the official repos.
           sudo pacman -Sy
           # Upgrade everything except python packages with pkgver=00 or 99.
           PKGEXT=.pkg.tar command pacaur -Su --ignore \
                 "$(pacman -Qm | grep '^python-.*-\(00\|99\)$' | cut -d' ' -f1 | paste -sd,)"
        else
           command pacaur "$@"
        fi
     }

  This function will not bypass Python packages explicitly installed from the
  AUR, as the user may have done so to bypass some incorrect packaging by
  ``pypi2pkgbuild.py``.  It is recommended to use the ``-i`` flag to calls
  to ``pypi2pkgbuild.py`` (e.g. in an alias) to exclude packages that are
  mishandled by ``pypi2pkgbuild.py`` (see `mispackaged packages`_).  The ``-i``
  flag can be passed multiple times; passing an empty argument to it will clear
  the ignore list defined so far.

  .. _mispackaged packages: TODO.rst#mispackaged-packages

- In order to package a locally available git repository, use

  .. code-block:: sh

     $ pypi2pkgbuild.py git+file://$absolute_path_to_repo  # (e.g. file:///home/...)

  In order to package a locally available sdist or wheel, use

  .. code-block:: sh

     $ pypi2pkgbuild.py file://$absolute_path_to_file  # (e.g. file:///home/...)

  Note that in both cases *absolute* paths are necessary.

  Building packages from local repos or wheels needs to be done in topological
  order of the dependencies (so that ``pypi2pkgbuild.py`` can find that
  the dependencies are actually present), or by passing the ``-d`` flag
  ("do not build dependencies"); if it is used, the Arch package may
  not use the correct dependency names (if they are not of the form
  ``python-pep503-normalized-name``).

- By default, ``pypi2pkgbuild.py`` ignores ``pip`` config files such as
  ``~/.config/pip/pip.conf``.  An explicitly set ``PIP_CONFIG_FILE`` will be
  respected, but may cause ``pypi2pkgbuild.py`` to fail as some ``pip`` calls
  will be unexpectedly modified.

  Likewise, user-site packages are ignored unless ``PYTHONNOUSERSITE`` is
  explicitly set to an empty value.

Build-time dependencies of packages
-----------------------------------

``pypi2pkgbuild.py`` attempts to guess whether ``Cython`` and ``SWIG`` are
build-time dependencies by checking for the presence of ``.pyx`` and ``.i``
files, respectively.  If this is not desired, set the ``--guess-makedepends``
option accordingly.

``pypi2pkgbuild.py`` guesses whether ``numpy`` is a build-time dependency by
attempting a build without ``numpy``, then, in case of failure, a build with
``numpy``.

Additional Python build-time dependencies (i.e., ``setup_requires``) can be
specified (as PyPI names) using the ``--setup-requires`` flag, or just as
normal entries using ``--pkgbuild-extras`` (they will be installed into the
build virtualenv).

Additional non-Python build-time dependencies can be set as ``makedepends``
using ``--pkgbuild-extras``; they will be installed *before*
``pypi2pkgbuild.py`` attempts to build a wheel for the package.

Vendored packages
-----------------

Some Arch packages (e.g. ``ipython``) include a number of smaller PyPI
packages.

Because it is not possible to assign a meaningful version automatically,
``pypi2pkgbuild.py`` instead creates an independent Arch package for each of
the PyPI packages (with two dashes in the name, to prevent name conflicts) and
a master package that depends on all of them.  The ``pkgrel`` of the master
package is set to ``$official_pkgrel.99``, so that the package appears more
recent than the current official version but older than any future official
version.  All these packages ``conflict`` with all versions of the official
package (except the newly created package), so upgrading should work fine when
the official package is actually updated.

However, dependencies are still expressed using the master package (to avoid
breakage on upgrade into an official package), so internal dependencies will
appear be circular.

All the packages are placed in a subfolder named ``meta:$pkgname``, so one can
easily install everything by ``cd``'ing there and running

.. code-block:: sh

   $ sudo pacman -U --asdeps **/*.xz
   $ sudo pacman -D --asexplicit $pkgname/$pkgname.tar.xz

Handling Python upgrades
------------------------

When the Python minor version (``x`` in ``3.x``) is upgraded, it is necessary
to regenerate all self-built packages.  This can be done e.g. with

.. code-block:: sh

   $ pypi2pkgbuild.py $(
        ls /usr/lib/python3.$oldver/site-packages |
        grep -Po '.*(?=-.*.dist-info)'
     )

Comparison with other tools
---------------------------

Other similar tools include pip2arch_, pip2pkgbuild_, and fpm_.  To the best
of my knowledge, the features below are unique to PyPI2PKGBUILD; please let me
know if this is incorrect.

- Supports wheels (the default is to prefer ``any``-platform wheels, then
  ``sdist``\s, then ``manylinux1`` wheels, but this can be changed using
  ``--pkgtypes``).
- Resolves Python dependencies via installation in a temporary virtualenv, and
  also creates PKGBUILDs for those that are not available as official packages.
- Resolves binary dependencies via ``namcap`` and adds them to the ``depends``
  array if they are installed (thus, it is suggested to first install
  them as ``--asdeps`` and then let the generated PKGBUILD pick them up as
  dependencies).  Note that some packages are distributed with a copy of the
  required libraries; in this case, ``pypi2pkgbuild.py``’s behavior will depend
  on whether the package defaults to using the system-wide library or its own
  copy.
- Automatically tries to fetch a missing license file from Github, if
  applicable.
- Automatically builds the package (with options given in ``--makepkg=...``)
  and run ``namcap``.
- Automatically builds all outdated dependencies via ``-u``.

.. _pip2arch: https://github.com/bluepeppers/pip2arch
.. _pip2pkgbuild: https://github.com/wenLiangcan/pip2pkgbuild
.. _fpm: https://github.com/jordansissel/fpm