Error when secondary galera servers are stopped and .my.cnf is present

[JCallicoat]

During incremental upgrade, secondary galera servers (galera[1:]) are shutdown by the mariadb-slaves-shutdown.yml play. An error is then encountered in the galera_server galera_server_cluster_state.yml tasks on galera[1]:

TASK [galera_server : Fail if galera_cluster_name doesnt match provided value] *****************************************************************************************************************************
fatal: [infra02_galera_container-6e8c2b47]: FAILED! => {"changed": false, "msg": "The galera_cluster_name variable does not match what is set in mysql. Check your galera_cluster_name setting in your user_*.yml files in "/etc/openstack_deploy" and compare to the current value in "/etc/mysql/conf.d/cluster.cnf" on the host, and the "wsrep_cluster_name" value set in your running galera cluster. To ignore the cluster state set '-e galera_ignore_cluster_state=true'.\n"}

Adding a debug task shows this is because the mysql command is trying to connect to mysql through local socket, which fails because the server is shutdown from mariadb-slaves-shutdown.yml.

- name: Print cluster name
  debug:
    msg: "Cluster name is {{ _cluster_name }}"

TASK [galera_server : Print cluster name] ******************************************************************************************************************************************************************
ok: [infra02_galera_container-6e8c2b47] => {
"msg": "Cluster name is {'msg': 'non-zero return code', 'cmd': ['mysql', '--silent', '--skip-column-names', '--connect-timeout=10', '-e', 'SHOW VARIABLES LIKE "wsrep_cluster_name";'], 'stdout': '', 'stderr': "ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)", 'rc': 1, 'start': '2021-03-27 23:09:05.538996', 'end': '2021-03-27 23:09:05.549118', 'delta': '0:00:00.010122', 'changed': False, 'failed': False, 'stdout_lines': [], 'stderr_lines': ["ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)"], 'failed_when_result': False}"
}

Upon further investigation, a /root/.my.cnf file is present specifying to use localhost:

root@infra02-galera-container-6e8c2b47:~# cat .my.cnf
[client]
host = localhost
user = root
password = <redacted>

It looks like this file is dropped by rpc-maas maas-infra-galera.yml play.