title: ZooKeeper alternatives? (cluster coordination service)
body: <p><a href="http://zookeeper.apache.org" rel="noreferrer">ZooKeeper</a> is a highly available coordination service for data centers. It originated in the Hadoop project. One can implement locking, fail over, leader election, group membership and other coordination issues on top of it.
  Are there any alternatives to ZooKeeper? (free software of course)</p>