Update to CentOS 7.5 causes addition of upstream CentOS repos

[Dmitry Sutyagin]

mos-updates package runs "yum -y update" as part of Fuel server update. If there's a switch to a new CentOS release (from 7.4 to 7.5), package centos-release-7-4... gets updated to centos-release-7-5. This adds back CentOS repositories which are removed during Fuel installation by anaconda:

### below is a clean state of Fuel with CentOS 7.4 after installation from ISO; after update of centos-release package, these files will get installed back:
[root@fuel ~]# rpm -V centos-release-7-4.1708.el7.centos.x86_64
S.5....T. c /etc/issue
missing c /etc/yum.repos.d/CentOS-Base.repo
missing c /etc/yum.repos.d/CentOS-CR.repo
missing c /etc/yum.repos.d/CentOS-Debuginfo.repo
missing c /etc/yum.repos.d/CentOS-Media.repo
missing c /etc/yum.repos.d/CentOS-Sources.repo
missing c /etc/yum.repos.d/CentOS-Vault.repo
missing c /etc/yum.repos.d/CentOS-fasttrack.repo

Now, if these repos get added back during the update, things start to break - for example offline installations start to fail because these repos are not accessible.

We need to either wipe these repo configs inside the playbook task, or modify the package to get rid of these files in it, or via some other means.

[Dmitry Sutyagin (dsutyagin)]

sla1 for 9.0-updates

[Denis Meltsaykin (dmeltsaykin)]

This is a known issue worked around in playbooks. Moving to 9.2-mu-8 to re-visit a fix and possibly find a better one.

[Denis Meltsaykin (dmeltsaykin)]

This is unfortunately a side effect of the centos-release package which we could not avoid back that times. This has been worked around in the commit to update playbooks: https://review.fuel-infra.org/gitweb?p=openstack/mos-updates.git;a=commit;h=99cd9838b1c70617fe2ae2a254d558ed9f7c8aca

Not sure if it's possible to invent more suitable solution if the upstream repos are already installed. Closing as Won't Fix.