Fix prechecks with Docker 20.10.0

The 'prechecks : Checking Docker version' task previously failed with
Docker 20.10.0. The regex used to parse the version was returning
0.10.0, which is not above the minimum. The previous version of 19.x
would have been parsed as 9.x, which is above the minimum.

This change fixes the issue by matching the beginning and end of the
version using \b.

Depends-On: https://review.opendev.org/766182

Change-Id: I2a23eea7effb5b9a5e73361bcd48bd2e16d1569c
Closes-Bug: 1907436

Author: markgoddard

ansible/roles/prechecks/tasks/service_checks.yml

@@ -6,7 +6,7 @@
   changed_when: false
   when: inventory_hostname in groups['baremetal']
   failed_when: result is failed
-               or result.stdout | regex_replace('.*(\\d+\\.\\d+\\.\\d+).*', '\\1')  is version(docker_version_min, '<')
+               or result.stdout | regex_replace('.*\\b(\\d+\\.\\d+\\.\\d+)\\b.*', '\\1')  is version(docker_version_min, '<')
 
 # NOTE(mgoddard): If passwords.yml is encrypted using ansible-vault, this check
 # will pass, but only because nothing in the vault file has the format of a

releasenotes/notes/bug-1907436-2da50ed38d107127.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes an issue with the ``kolla-ansible prechecks`` command with Docker
+    20.10. `LP#1907436
+    <https://bugs.launchpad.net/kolla-ansible/+bug/1907436>`__