Docker containers for different Ansible versions.
The image purpose is related to make different tests with different versions of Ansible and verify backward compatibility
Also there is official images of it, just check the URLs
Installed new packages with pip to allow testing on destination nodes.
- testinfra (to use ansible as a backend)
- python-shade modules to manage openstack
Why not different Virtual Envs?
If your base release are Ansible 2.0 you cannot install a 1.9 version of Ansible because it Dependency libraries
Hope this be useful for you.