Fix the Prechecks failed while checking docker version

In Docker version 18.01.0-ce, "docker version" command uses the
"\t" to format the result, which will cause the prechecks failed.
There is a workaround that using "docker --version" command
instead of "docker version" can get everything running.
Also, using "docker --version" to check the version of docker is
more specific and effective.

backport: pike ocata

Change-Id: Ie5efe1888afc3be11441a88d627db62e1575f3ed
Closes-Bug: #1742869
(cherry picked from commit d1ddeddb67)

ansible/roles/prechecks/tasks/service_checks.yml

@@ -1,11 +1,11 @@
 ---
 - name: Checking Docker version
-  command: docker version
+  command: docker --version
   register: result
   changed_when: false
   when: inventory_hostname in groups['baremetal']
   failed_when: result | failed
-               or (result.stdout | from_yaml).Server.Version | regex_replace('(\\d+\\.\\d+\\.\\d+).*', '\\1') | version_compare(docker_version_min, '<')
+               or result.stdout | regex_replace('.*(\\d+\\.\\d+\\.\\d+).*', '\\1') | version_compare(docker_version_min, '<')
 
 - name: Checking empty passwords in passwords.yml. Run kolla-genpwd if this task fails
   local_action: command grep '^[^#].*:\s*$' "{{ CONFIG_DIR | default('/etc/kolla') }}/passwords.yml"