Thx Jay.
I stopped the firewalld daemon, restart docker and the faulty container and the error is still the same (in production.log):
Error connecting to Redis on localhost:6379 (Errno::ENETUNREACH) subscribe failed, reconnecting in 1 second.
I connected to the docker container:
docker exec --privileged -it <container id> bash
I can see redis running:
redis 45 0.2 0.1 45936 4352 ? Sl 05:29 0:02 /usr/bin/redis-server *:6379
Any idea?