• https://www.digitalocean.com/community/tutorials/how-to-configure-a-galera-cluster-with-mariadb-10-1-on-ubuntu-16-04-servers

Three Ubuntu 16.04 servers

apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xF1656F24C74CD1D8
add-apt-repository 'deb [arch=amd64] http://nyc2.mirrors.digitalocean.com/mariadb/repo/10.1/ubuntu xenial main'
apt update
apt install mariadb-server rsync