Does Redis Pub/Sub work with master-slave replication?

In short: yes! To see this, start two Redis servers in master-slave configuration, then subscribe to channel foo on the slave:

$ redis-server --port 6379 &
$ redis-server --port 6380 --slaveof 6379 &
$ redis-cli -p 6380 subscribe foo
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "foo"

Now publish something to foo on the master:

$ redis-cli -p 6379 publish foo bar

You’ll find that this message does arrive at the client subscribed on the slave:

1) "message"
2) "foo"
3) "bar"

All publish commands are replicated to the slave. You can see this by first sending the sync command to the Redis master using redis-cli, which then becomes a Redis slave and prints all replicated commands:

$ redis-cli -p 6379 sync
Entering slave output mode...  (press Ctrl-C to quit)
SYNC with master, discarding 76 bytes of bulk transfer...
SYNC done. Logging commands from master.

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Tagged #programming, #redis. All content copyright James Fisher 2019. This post is not associated with my employer. Found an error? Edit this page.