Cyril Roelandt

In this talk, we will introduce the Universal Packaging Tool (upt), a modular tool meant to help packagers in their daily tasks. We will show how it is an improvement over similar existing tools, which upt means to replace. This will be especially interesting for distribution developers that have had to deal with upstream platforms such as PyPI, CPAN or RubyGems.

Nowadays, most languages come with a package manager (such as pip or gem) that can install packages from an upstream package archive (such as pypi.org or rubygems.org). Traditional distributions (such as Debian, Fedora or OpenBSD) still package these same pieces of software, making them available through their own package manager (such as apt, dnf or the OpenBSD ports).

Over the years, multiple scripts have been written in order to automate part of the packaging process. Tools like pypi2deb (which turns a package from PyPI into a Debian package) or gem2rpm (which turns a package from RubyGems into an RPM package) make the work of packagers much easier. There are a lot of these tools, and they all behave a bit differently, expose a different interface to their users, and duplicate a lot of code.

In this presentation, I will introduce the Univesal Packaging Tool (upt), a modular program that allows packagers to create packages from any language-specific upstream archive to any GNU/Linux or *BSD distribution. We will show how this is done without any code duplication, and how any improvement to this tool will benefit developers from all distributions.

Tox is a very well-known tool, written in Python, that allows users to run tests inside various virtual environments created using virtualenv. This approach prevents tests from being truly reproducible. We will see in this talk how virtualenv can be replaced by GNU Guix, a functional package manager, in order to improve tox. We will give real-life examples using Python packages from the OpenStack project.

Using virtualenv in tox raises a few issues:

• only the packages available on PyPI can be installed, which means users sometimes have to "manually" install some packages using their distribution's package manager (for instance, lib*-dev on Debian, gcc...);
• when multiple virtual environments need to install the same package, it is duplicated in each of the virtualenvs, wasting disk space;
• bad level of abstraction: nowadays, every language come with its own package manager (pip, npm, cpan...) instead of using a single, robust package manager;
• tests are not really reproducible because the test environments are not completely isolated from the rest of the system (think of environment variables, of the whole filesystem, etc.).

GNU Guix is a functional package manager (as in "functional programming") based on Nix. It allows users to build packages in a completely isolated environment. We will introduce this tool and show how the "guix environment" command can be used to create an isolated environment similar to a virtualenv.

Last but not least, we will see how virtualenv can be replaced with Guix in tox so that users can benefit from all the features of Guix without changing their usual workflow. We will show some examples using packages from the OpenStack project, such as python-keystoneclient.