* A reliable DNS setup cannot be assumed in MicroStack installations so
relying on the host cache behavior of MySQL is not reliable. MySQL resolves
an IP address to a host name and resolves that host name back to an IP
address (https://dev.mysql.com/doc/refman/8.0/en/host-cache.html);
* IP addresses are not guaranteed to be static in a MicroStack
deployment although this is preferable. Likewise, for services like
cinder-volume to access the database on secondary nodes they need to
be allowed to do that at the MySQL ACL level.
Change-Id: Ib87ab0a71fa83dad8e8ddb40f34907ab24999423
6087f4cb3b