1.3 Using Redis sentinels

Redis sentinels is one of the two options to create a high availability service. It consists of minimally three Redis servers and mininally three sentinel servers. The sentinel servers monitor the Redis servers and will initiate a fail-over when the master becomes disfunctional and certain safety constraints are satisfied. A client needs to be aware of this setup. It is given an initial list with (a subset of) the known sentinels. The client attempts to connect to one of the sentinels and ask it for the current Redis master server. Details are described in Sentinel client spec. The SWI-Prolog client maintains the actual list of sentinels dynamically after successful discovery of the first sentinel. Below is an example redis_server/3 to connect to a sentinel network. The Address specification sentinel(swish) tells the library we want to connect to a sentinel network that is monitored under the name swish.

:- redis_server(swish_sentinel, sentinel(swish),
                [ user(janbob),
                  password("topsecret"),
                  version(3),
                  sentinels([ host1:26379,
                                  host2:26379,
                                  host3:26379
                                ])
                ]).