Installing the MariaDB Galera cluster

OpenStack can be backed by a number of database backends, and one of the most common options is MySQL or its other open source fork, MariaDB. There are a number of ways to make MariaDB more resilient and highly available. The following approach uses a Load Balancer to front a multi-read/write master with Galera, taking care of the synchronous replication required in such a setup. Galera is a synchronous multimaster cluster for MariaDB InnoDB databases. Galera clusters allow synchronous data writes across all nodes with any node being able to take that write in a fully active/active topology. It features automatic node management- that is, failed nodes are removed from the cluster and new nodes are automatically registered. The advantage of this is that we are adding resilience in the event of a database node failure, as each node stores a copy of the data. Galera clusters consist of odd-numbered nodes. This is important when a node fails. Galera takes...