Multi-Python Image

This repository defines a Python image based on Ubuntu with multiple Python versions installed, along with the tox executable. It is meant to use in CI for test purposes.

It supports both ARM and AMD architectures.

Python versions

The list of Python versions to install is passed as arguments (see Dockerfile). One Python version must be selected as "main" - it will be used to install tox. Along with "regular" Python versions, one pypy version will also be installed.

The main python version is set as the default in the container (python and python3).

IMPORTANT: Python versions must be available either in the official Ubuntu repositories or in the deadsnakes PPA. The PyPy version should be available at https://www.pypy.org/download.html.

Usage

Run the following from a terminal at the root of your Python project:

docker run --rm -it -v $(PWD):/app divio/multi-python:latest tox

The default user is tox. If you need to install extra dependencies, tox has sudo rights so it is possible to run sudo apt update && sudo apt install ....

Development

After updating the Python versions in the Dockerfile, ensure you also update test/tox.ini to reflect the change.

About pip

As stated in https://packaging.python.org/en/latest/guides/installing-using-linux-tools/#debian-ubuntu:

Recent Debian/Ubuntu versions have modified pip to use the “User Scheme” by default, which is a significant behavior change that can be surprising to some users.

In other words, pip now installs libraries and executables in $HOME/.local (or /home/tox/.local in this image).

This has no impact, except when running commands as sudo. Just keep in mind the root user doesn't have the same packages installed.