This Git repo is derived from the official Docker image for mariadb.
The basic behaviour of the official mariadb container is preserved (initialisation, users, passwords and so on).
Support for Galera clustering has been added. Configuration is via /etc/mysql/conf.d which is a volume. To active Galera you need to mount that volume and put a appropriate .cnf file in there. A sample cluster.cnf for bootstrapping a cluster is provided.
Extra ports are exposed for the clustering. Bootstrapping the cluster is the same - refer to the official docs for galera.