Redis is used as a key-value store for rspamd's and (some of) mailcow's settings and data. If you are unfamiliar with redis please read the introduction to redis and maybe visit this wonderful guide on how to use it.
To connect to the redis cli execute:
docker compose exec redis-mailcow redis-cli
Here are some useful commands for the redis-cli for debugging:
Listens for all requests received by the server in real time:
# docker compose exec redis-mailcow redis-cli 127.0.0.1:6379> monitor OK 1494077286.401963 [0 172.22.1.253:41228] "SMEMBERS" "BAYES_SPAM_keys" 1494077288.292970 [0 172.22.1.253:41229] "SMEMBERS" "BAYES_SPAM_keys" [...]
Get all keys matching your pattern:
Test a connection:
127.0.0.1:6379> PING PONG
If you want to know more, here is a cheat sheet.