command like
  ansible-playbook -i prod pull-image.yml

fails with test:
fatal: [127.0.0.1]: FAILED! => {"changed": false, "msg": "Failed to import
docker or docker-py - No module named 'docker'. Try `pip install docker` or
`pip install docker-py` (Python 2.6)"}

After then i downgrade ansible to 2.5.1 this book plays without problems.

openSUSE Leap 15.0
docker                 18.09.1_ce-lp150.5.13.1
docker-bash-completion 18.09.1_ce-lp150.5.13.1
docker-compose         1.17.0-lp150.2.3
docker-libnetwork      0.7.0.1+gitr2711_2cfbf9b1f981-lp150.3.10.1
docker-runc            1.0.0rc6+gitr3748_96ec2177ae84-lp150.5.14.1
python-dockerpty       0.4.1-lp150.1.3
python2-docker         2.6.1-lp150.2.1
python2-docker-pycreds 0.2.1-lp150.1.3