Apuppetreceiptfor[ApacheZookeeper](http://zookeeper.apache.org/). ZooKeeper is a high-performance coordination service for maintaining configuration information, naming, providing distributed synchronization, and providing group services.
[Observers](http://zookeeper.apache.org/doc/r3.3.0/zookeeperObservers.html) were introduced in ZooKeeper 3.3.0. To enable this feature simply state which of ZooKeeper servers are observing:
*Debian6Squeeze:youcangetZooKeeperpackagefrom[Wheezy](http://packages.debian.org/wheezy/zookeeper) or [Sid](http://packages.debian.org/sid/zookeeper) repo.