© 2013. A HashiCorp Project. 
Serf relies on an efficient and lightweight gossip protocol to communicate with nodes. The Serf agents periodically exchange messages with each other in much the same way that a zombie apocalypse would occur: it starts with one zombie but soon infects everyone. In practice, the gossip is very fast and extremely efficient.
Serf is able to quickly detect failed members and notify the rest of the cluster. This failure detection is built into the heart of the gossip protocol used by Serf. Like humans in a zombie apocalypse, everybody checks their peers for infection and quickly alerts the other living humans. Serf relies on a random probing technique which is proven to efficiently scale to clusters of any size.
In addition to managing membership, Serf can broadcast custom events. These can be used to trigger deploys, restart processes, spread tales of human heroism, and anything else you may want. The event system is flexible and lightweight, making it easy for application developers and sysadmins alike to leverage.