Sentinel support

aredis can be used together with Redis Sentinel to discover Redis nodes. You need to have at least one Sentinel daemon running in order to use aredis’s Sentinel support.

Connecting aredis to the Sentinel instance(s) is easy. You can use a Sentinel connection to discover the master and slaves network addresses:

from redis.sentinel import Sentinel
sentinel = Sentinel([('localhost', 26379)], stream_timeout=0.1)
await sentinel.discover_master('mymaster')
# ('', 6379)
await sentinel.discover_slaves('mymaster')
# [('', 6380)]

You can also create Redis client connections from a Sentinel instance. You can connect to either the master (for write operations) or a slave (for read-only operations).

master = sentinel.master_for('mymaster', stream_timeout=0.1)
slave = sentinel.slave_for('mymaster', stream_timeout=0.1)
master.set('foo', 'bar')
# 'bar'

The master and slave objects are normal StrictRedis instances with their connection pool bound to the Sentinel instance. When a Sentinel backed client attempts to establish a connection, it first queries the Sentinel servers to determine an appropriate host to connect to. If no server is found, a MasterNotFoundError or SlaveNotFoundError is raised. Both exceptions are subclasses of ConnectionError.

When trying to connect to a slave client, the Sentinel connection pool will iterate over the list of slaves until it finds one that can be connected to. If no slaves can be connected to, a connection will be established with the master.

See Guidelines for Redis clients with support for Redis Sentinel to learn more about Redis Sentinel.