py2deb 5.0

Description:

py2deb 5.0

The Python package py2deb converts Python source distributions to Debian
binary packages (the ones used for installation). It uses pip-accel (based on
pip) to download, unpack and compile Python packages. Because of this py2deb
is compatible with the command line interface of the pip install command.
For example you can specify packages to convert as command line arguments but
you can also use requirement files if you want.
During the conversion process dependencies are automatically taken into account
and converted as well so you don’t actually have to use requirement files
including transitive dependencies. In fact you might prefer not explicitly
listing your transitive dependencies in requirement files because py2deb will
translate the version constraints of Python packages into Debian package
relationships.
The py2deb package is currently tested on CPython 2.7, 3.5, 3.6, 3.7 and
PyPy 2 and 3. Unfortunately Python 3.8+ is not yet supported (see below). For
usage instructions please refer to the documentation hosted on Read The
Docs.


Installation
Usage

Command line


Future improvements

Python 3.8+ compatibility
Installation of system wide files
Conversion of binary wheels
Full PEP-440 compatibility


Similar projects
Contact
License



Installation
The py2deb package is available on PyPI, so installation is very simple:
$ pip install py2deb
There are some system dependencies which you have to install as well:
$ sudo apt-get install dpkg-dev fakeroot
Optionally you can also install Lintian (which is not a hard dependency but
more of a “nice to have”):
$ sudo apt-get install lintian
When Lintian is installed it will be run automatically to sanity check
converted packages. This slows down the conversion process somewhat but can be
very useful, especially when working on py2deb itself. Currently py2deb doesn’t
fail when Lintian reports errors, this is due to the unorthodox ways in which
py2deb can be used. This may change in the future as py2deb becomes more
mature.


Usage
There are two ways to use the py2deb package: As the command line program
py2deb and as a Python API. For details about the Python API please refer
to the API documentation hosted on Read the Docs. The command line interface
is described below.

Command line
Usage: py2deb [OPTIONS] …
Convert Python packages to Debian packages according to the given
command line options (see below). The command line arguments are the
same as accepted by the “pip install” command because py2deb invokes
pip during the conversion process. This means you can name the
package(s) to convert on the command line but you can also use
“requirement files” if you prefer.
If you want to pass command line options to pip (e.g. because you want
to use a custom index URL or a requirements file) then you will need
to tell py2deb where the options for py2deb stop and the options for
pip begin. In such cases you can use the following syntax:
$ py2deb -r /tmp -- -r requirements.txt
So the “–” marker separates the py2deb options from the pip options.
Supported options:






Option
Description



-c, --config=FILENAME
Load a configuration file. Because the command line arguments are processed
in the given order, you have the choice and responsibility to decide if
command line options override configuration file options or vice versa.
Refer to the documentation for details on the configuration file format.
The default configuration files /etc/py2deb.ini and ~/.py2deb.ini are
automatically loaded if they exist. This happens before environment
variables and command line options are processed.
Can also be set using the environment variable $PY2DEB_CONFIG.


-r, --repository=DIRECTORY
Change the directory where *.deb archives are stored. Defaults to
the system wide temporary directory (which is usually /tmp). If
this directory doesn’t exist py2deb refuses to run.
Can also be set using the environment variable $PY2DEB_REPOSITORY.


--use-system-package=PYTHON_PACKAGE_NAME,DEBIAN_PACKAGE_NAME
Exclude a Python package (the name before the comma) from conversion and
replace references to the Python package with a specific Debian package
name. This allows you to use system packages for specific Python
requirements.

--name-prefix=PREFIX
Set the name prefix used during the name conversion from Python to
Debian packages. Defaults to “python”. The name prefix and package
names are always delimited by a dash.
Can also be set using the environment variable $PY2DEB_NAME_PREFIX.


--no-name-prefix=PYTHON_PACKAGE_NAME
Exclude a Python package from having the name prefix applied
during the package name conversion. This is useful to avoid
awkward repetitions.

--rename=PYTHON_PACKAGE_NAME,DEBIAN_PACKAGE_NAME
Override the package name conversion algorithm for the given pair
of package names. Useful if you don’t agree with the algorithm :-)

--install-prefix=DIRECTORY
Override the default system wide installation prefix. By setting
this to anything other than “/usr” or “/usr/local” you change the
way py2deb works. It will build packages with a file system layout
similar to a Python virtual environment, except there will not be
a Python executable: The packages are meant to be loaded by
modifying Python’s module search path. Refer to the documentation
for details.
Can also be set using the environment variable $PY2DEB_INSTALL_PREFIX.


--install-alternative=LINK,PATH
Use Debian’s “update-alternatives” system to add an executable
that’s installed in a custom installation prefix (see above) to
the system wide executable search path. Refer to the documentation
for details.

--python-callback=EXPRESSION
Set a Python callback to be called during the conversion process. Refer to
the documentation for details about the use of this feature and the syntax
of EXPRESSION.
Can also be set using the environment variable $PY2DEB_CALLBACK.


--report-dependencies=FILENAME
Add the Debian relationships needed to depend on the converted
package(s) to the given control file. If the control file already
contains relationships the additional relationships will be added
to the control file; they won’t overwrite existing relationships.

-y, --yes
Instruct pip-accel to automatically install build time dependencies
where possible. Refer to the pip-accel documentation for details.
Can also be set using the environment variable $PY2DEB_AUTO_INSTALL.


-v, --verbose
Make more noise :-).

-h, --help
Show this message and exit.






Future improvements
The following sections list possible improvements to the project:


Python 3.8+ compatibility
Installation of system wide files
Conversion of binary wheels
Full PEP-440 compatibility



Python 3.8+ compatibility
The py2deb project builds on top of pip-accel, which was developed between
2013 and 2015 on top of pip >= 7.0, < 7.2. Since that time pip has grown
enormously: At the time of writing (in August 2020) we’re now at pip 20!
None of the improvements made between pip 7-20 are available in pip-accel and
py2deb and this has become somewhat of a glaring issue that plenty of users
have run into (see #17, #18, #27 and #31).
Known issues being caused by this include:

The old pip version prevents Python 3.8+ compatibility.
The old pip version doesn’t know about python_requires metadata provided
by PyPI and this forces users to maintain constraints files themselves, even
though this shouldn’t be necessary.
While pip-accel supports installation from wheels, it was never exposed via
the Python API and so py2deb lacks support for converting wheels (it
currently needs source distributions).

The current state of affairs is best summarized in this comment. I’m hoping
to complete the upgrade to newer pip and pip-accel releases in the coming weeks
(as of this writing in August 2020) but can’t commit to a date.


Installation of system wide files
Find a way to facilitate (explicit / opt-in) installation of system wide files
(not related to Python per se) based on a Python distribution? This could
significantly reduce the need for “wrapper packages” that basically just pull
in packages converted by py2deb and drop a few configuration files into place.

Related issues:
See issue #7 for a related discussion.




Conversion of binary wheels
Investigate the feasability of supporting conversion of binary wheels. Slowly
but surely the Python community seems to be gravitating towards (binary) wheels
and once gravity has shifted we don’t want to be left in the dust! 😉


Full PEP-440 compatibility
Dive into PEP-440 and see if it can be fully supported? Then this question on
Reddit can finally get a satisfying answer 🙂.



Similar projects
There are several projects out there that share similarities with py2deb, for
example I know of stdeb, dh-virtualenv and fpm. The documentation includes a
fairly detailed comparison with each of these projects.


Contact
The latest version of py2deb is available on PyPI and GitHub. The
documentation is hosted on Read the Docs and includes a changelog. For
questions, bug reports, suggestions, etc. please create an issue on GitHub.


License
This software is licensed under the MIT license.
© 2020 Peter Odding, Arjan Verwer and Paylogic International.