sunetdrive/templates/mariadb_backup/02-backup_user.sql.erb

CREATE USER 'backup'@'localhost' IDENTIFIED BY '<%= @backup_password %>';
GRANT SELECT, INSERT, CREATE, RELOAD, PROCESS, SUPER, LOCK TABLES, REPLICATION SLAVE, REPLICATION CLIENT, SHOW VIEW, EVENT, CREATE TABLESPACE ON *.* TO 'backup'@'localhost';