Easier to maintain server and client configuration with one file (/etc/my.cnf) as xtrabackup doesn't understand !include directive. Xtrabackup also reads the datadir from the configuration even if it's the default one. You need MariaDB version >= 10.0.10 for xtrabackup-v2.
wsrep_sst_auth=xtra:dunkgonkBlong wsrep_sst_method=xtrabackup-v2 datadir=/var/lib/mysql
yum install http://www.percona.com/downloads/percona-release/redhat/0.1-3/percona-release-0.1-3.noarch.rpm yum install percona-xtrabackup.x86_64
Mysql user for xtrabackup
GRANT RELOAD, LOCK TABLES, REPLICATION CLIENT, SUPER ON *.* TO xtra@'localhost' identified by 'dunkgonkBlong';