ansible returns with “Failed to import the required Python library (Docker SDK for Python: docker (Python >= 2.7) or docker-py (Python 2.6))

It appears that you don’t have the docker module installed.

You will need to install it via your system package manager (apt install python-docker, for example), or using pip (pip install docker).

If you have multiple Python versions, make sure that you’ve installed the docker module into the version that Ansible is using.