$ vim /etc/rundeck/rundeck-config.properties
  #dataSource.url = jdbc:h2:file:/var/lib/rundeck/data/rundeckdb;MVCC=true #Comment
  dataSource.url = jdbc:mysql://myserver/rundeckdb?autoReconnect=true
  dataSource.username = dbuser
  dataSource.password = dbpass
  #rundeck.log4j.config.file = /etc/rundeck/log4j.properties #Comment

$ systemctl restart rundeckd