Unable to connect to Redis cluster client using kubectl port-forward

[jppade]

What do we want to do?
Connect to a Redis cluster (consisting of 3 masters and 3 slaves) running in Kubernetes using kubectl port-forward to localhost:6379.
The client looks as follows:

func GetRedisClient() *redis.ClusterClient {
	var redisClusterClient *redis.ClusterClient
	password := utils.Getenv("REDISPASSWORD", "")
	addresses := strings.Split(utils.Getenv("REDIS_ADDRS", "localhost:6379"), ",")
	redisClusterClient = redis.NewClusterClient(&redis.ClusterOptions{
		Password:    password,
		Addrs:       addresses,
	})
	pong, err := redisClusterClient.Ping(context.Background()).Result()
	if err != nil {
		log.Error("NewDataStore redis: ", err)
	}
	log.Debug("redisFailoverClient", pong)
	return redisClusterClient
}

Connection from localhost works fine with redis-cli -c -p 6379 -a redis_password using the port-forward.

Expected Behavior

Connect to remote redis cluster.

Current Behavior

The following error:
dial tcp remote_ip:6379: connect: no route to host
Where remote_ip is the ip address of a master node in the cluster, i.e. the first master obtained by cluster slots.
It looks as if the cluster client library reroutes localhost:6379 to a cluster node and tries to reconnect, which obviously fails.

Possible Solution

Not a solution, but we tried adding

TLSConfig: &tls.Config{
	ServerName: "you domain",
},

to redis.Options in the cluster client such as proposed in #1698. This did not work though.

[monkey92t]

I don't quite understand what it means. The go-redis connection to redis-cluster is different from a standalone Redis connection. It will use the node address returned by redis-cluster (CLUSTER NODES). If it's a local address, it won't be accessible from outside.

[ak2766]

I guarantee you that although the redis-cli connects, you will not be able to set a key. If you try it, you'll get output similar to:

Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.
122.0.0.1:6379> set myname akk
-> Redirected to slot [12807] located at 10.233.52.247:6379

That is trying to redirect you to a node in the cluster (10.233.52.247) which you obviously cannot reach.

I believe that part of the go-redis functionality is to verify connectivity by trying to write to the cluster whereby it fails hence returns an error. Just my hypothesis.