Supplements node_redis with Redis Sentinel support. Redis Sentinel is a system designed to help managing Redis instances. It performs the following three tasks: Monitoring. Sentinel constantly check if your master and slave instances are working as expected. Notification. Sentinel can notify the system administrator, or another computer program, via an API, that something is wrong with one of the monitored Redis instances. Automatic failover. If a master is not working as expected, Sentinel can start a failover process where a slave is promoted to master, the other additional slaves are reconfigured to use the new master, and the applications using the Redis server informed about the new address to use when connecting.