Redis host. Ignored when <a href="/nixpkgs/option/services.romm.redis.createLocally"><a href="/nixpkgs/option/services.romm.redis.createLocally" rel="nofollow">services.romm.redis.createLocally</a></a> is set; credentials for a remote Redis are passed via <a href="/nixpkgs/option/services.romm.environmentFile"><a href="/nixpkgs/option/services.romm.environmentFile" rel="nofollow">services.romm.environmentFile</a></a> (<code>REDIS_PASSWORD</code>, and <code>RQ_REDIS_URL</code> for the job queue).