Iterating on ancient versions of Python

Some of the failures that we encounter only arise in ancient versions of python. It can be non-trivial to install these versions on a production machine, and possibly not desirable. In these situations LXD comes to our aid.

Save the following cloud-init file in python35_cloud_init.yaml:

#cloud-config
runcmd:
  - add-apt-repository --yes ppa:deadsnakes/ppa
  - apt update -q -y
  - apt install -q -y "python3.5" "python3.5-venv" "python3.5-dev" gcc "flake8" "shellcheck"
  - python3.5 -m ensurepip
  - python3.5 -m venv /root/venv
  - PIP_TRUSTED_HOST="pypi.python.org pypi.org files.pythonhosted.org" /root/venv/bin/python3.5 -m pip install --upgrade "pip<21"
  - git clone https://github.com/canonical/checkbox /root/checkbox
  - PIP_TRUSTED_HOST="pypi.python.org pypi.org files.pythonhosted.org" /root/venv/bin/python3.5 -m pip install -e /root/checkbox/checkbox-ng
  - PIP_TRUSTED_HOST="pypi.python.org pypi.org files.pythonhosted.org" /root/venv/bin/python3.5 -m pip install -e /root/checkbox/checkbox-support
  - /root/venv/bin/python3.5 /root/checkbox/providers/resource/manage.py develop
  - /root/venv/bin/python3.5 /root/checkbox/providers/base/manage.py develop

Use lxc to launch a focal container with the cloud-init file provided, log into it and wait for cloud-init to finish preparing your environment

$ lxc launch ubuntu:focal python35 --config=user.user-data="$(cat python35_cloud_init.yaml)"
$ lxc shell python35
root@python35:~# cloud-init status --wait
...........................................status: done

The cloud-init file has prepared you a fresh clone of the Checkbox repo in /root/checkbox, it has created a venv you can use in /root/venv with Python3.5 and it has developed the resource and base provider. You should now be able to iterate on your tests!