add galera cluster name

templates/etc/mysql/conf.d/09-galera.cnf.j2

@@ -14,7 +14,9 @@ wsrep_provider=/usr/lib/galera/libgalera_smm.so
 wsrep_cluster_address=gcomm://{{ mariadb_galera_members | join(",") }}
 # TODO: https://mariadb.com/kb/en/mariadb/galera-cluster-system-variables/#wsrep_sst_method
 wsrep_sst_method=rsync
-# TODO: wsrep_cluster_name="my_wsrep_cluster"
+{% if mariadb_wsrep_cluster_name is defined %}
+wsrep_cluster_name="{{ mariadb_wsrep_cluster_name }}"
+{% endif %}
 
 # Node Configuration
 wsrep_node_address="{{ mariadb_wsrep_node_address | default(ansible_default_ipv4.address) }}"