Description of problem:
Validator check-repo-availability.yaml is running the 'yum' command directly, and the GUI user ends up seeing a warning instead of a successful result. When clicking on the validator to see the text of the warning, it turns out that it's just a recommendation to use the ansible yum module...
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Run the validator: "Check availability of current repositories"
Success, without warnings
A similar bug was filed for the validator "Check if ceph-ansible is installed on the undercloud". There is already a fix for that bug. See bug #1516397 for details.
Ana is actually working on improving this validation  and this issue will be fixed with her patch 
 - https://review.openstack.org/#/c/515412/
Verified in: openstack-tripleo-validations-8.4.0-2.el7ost.noarch
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.