Bug 1902849

Description of problem:
on step 19.2 of the upgrade documentation -- > https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/16.1/html/framework_for_upgrades_13_to_16.1/upgrading-an-overcloud-with-external-ceph-deployments_upgrading-overcloud-external-ceph#running-the-overcloud-upgrade-preparation-upgrading-overcloud-external-ceph

The upgrade command which is failing is -->  openstack overcloud upgrade run --stack STACK NAME --tags system_upgrade --limit xxxx

Failure message :


2020-11-24 12:55:22,143 p=100846 u=mistral n=ansible | TASK [tripleo-podman : Stop a container] ***************************************
2020-11-24 12:55:22,143 p=100846 u=mistral n=ansible | Tuesday 24 November 2020  12:55:22 -0500 (0:00:00.326)       0:00:32.456 ******
2020-11-24 12:55:22,805 p=100846 u=mistral n=ansible | failed: [xxxxx] (item=985976509ce8) => {"ansible_loop_var": "item", "changed": false, "item": "985976509ce8", "msg": "Failed to import the required Python library (Docker SDK for Python: docker (Python >= 2.7) or docker-py (Python 2.6)) on xxxxx's Python /usr/bin/python. Please read module documentation and install in the appropriate location. If the required library is installed, but Ansible is using the wrong Python interpreter, please consult the documentation on ansible_python_interpreter, for example via `pip install docker` or `pip install docker-py` (Python 2.6). The error was: No module named docker"}
2020-11-24 12:55:23,159 p=100846 u=mistral n=ansible | failed: [xxxx] (item=06ce45f22ce4) => {"ansible_loop_var": "item", "changed": false, "item": "06ce45f22ce4", "msg": "Failed to import the required Python library (Docker SDK for Python: docker (Python >= 2.7) or docker-py (Python 2.6)) on xxxxx's Python /usr/bin/python. Please read module documentation and install in the appropriate location. If the required library is installed, but Ansible is using the wrong Python interpreter, please consult the documentation on ansible_python_interpreter, for example via `pip install docker` or `pip install docker-py` (Python 2.6). The error was: No module named docker"}


Version-Release number of selected component (if applicable):
osp13

How reproducible:
unknown

Steps to Reproduce:
1. attempt ffu on systems that were upgraded from osp10 timeframe to osp13
2.
3.

Actual results:
update fails

Expected results:
update works.

Additional info:

I found that the package python-docker contains the module needed it seems. This rpm is in the osp13 image, however the rpm isn't on osp10 systems. So this problem occurs when older environments are upgraded. 


[root@undercloud-0 docker]# grep -ir "import docker" /usr/lib/python2.7/site-packages/docker
/usr/lib/python2.7/site-packages/docker/__init__.py:from .client import DockerClient, from_env
/usr/lib/python2.7/site-packages/docker/api/client.py:        >>> import docker
...
...
[root@undercloud-0 docker]# rpm -q --whatprovides /usr/lib/python2.7/site-packages/docker/__init__.py
python-docker-2.4.2-2.el7.noarch