How to switch redis master in sentinel configuration

Question

I have a redis sentinel configuration with one master, two slaves and 3 sentinels running. I noticed that at some point the sentinels may switch the master electing one of the slaves as master. This is causing problems to an application which is connecting to the master node as a standalone client(I'm working on changing the code to use sentinels). I wanted to know if it is possible to switch the master by connecting to the sentinel client i.e. through 'redis-cli'

Can somebody let me know if there is a command that I can use to switch the master IP?

Answer 1

You can manually trigger a failover by running:
redis-cli -a {password} -p {sentinel_port} SENTINEL failover {cluster_name}

Answer 2

The client applications should use a client library that supports sentinel in the case where a redis master goes down and the sentinels select a new master. Not sure how beneficial it is to have sentinel setup if your client applications are not taking advantage of it. A client application that supports sentinel will query sentinel for the master ip and should be somewhat tolerant to faults occurring with the master connection. You can trigger a manual failover like the other answer states:

redis-cli -h {sentinel-ip} -p {26379 or sentinel port} sentinel failover {mastername}

But you will not be able to pick which node it fails over to. You can control a configuration value slave_priority in the redis.conf file so that it prefers a node over the rest. A description of the slave priority can be found here: https://redis.io/topics/sentinel