Can not use a specified DB with NewFailoverClusterClient. suggested possible fix

[Ankit-Kulkarni]

If you create a redis client using sentinel failover options but you have to use a different db than 0 and route your read only queries to slaves , different db number is not honoured.

Library version I used: v8.11.5

Expected Behavior

We would expect the NewFailoverClusterClient to honor the DB mentioned in FailoverOptions.

Currently I am using redis.FailoverOptions to create a *redis.ClusterClient using NewFailoverClusterClient. I wanted to route read only queries to slaves and hence using NewFailoverClusterClient instead of NewFailoverClient. My failover configuration has a DB say 5 but when i use *redis.ClusterClient it does all operations on db 0 only. Reference code below

var rdClient *redis.ClusterClient
func initRedis() (*redis.ClusterClient) {
	redisSentinels := strings.Split(config["redisSentinels"], ",")
	for i := range redisSentinels {
		redisSentinels[i] = strings.TrimSpace(redisSentinels[i])
	}

	clientConfig := &redis.FailoverOptions{
		MasterName:    config["redisMasterName"],
		SentinelAddrs: redisSentinels,
		RouteRandomly: true,
		PoolSize:      5,
		DB:            5,
		....
		.....
	}

	return redis.NewFailoverClusterClient(clientConfig)
	
}
rdclient = initRedis()

Above rdsClient when doing set or get will work only on db:0 and not db:5

Possible Solution

I think the issue is because the ClusterOptions struct doesn't support DB(may be intentional but i couldn't figure out why). I tried quick local modification to library for below structs and functions and it seemed to work. But not sure if this change misses/breaks anything else (specifically if this was unintentional)

// file --> cluster.go
type ClusterOptions struct {
         ...
        // DB of the new client
	DB int
         ...
}

func (opt *ClusterOptions) clientOptions() *Options {
	const disableIdleCheck = -1

	return &Options{
		DB:        opt.DB,
                ....
                ....
	}
}


// file --> sentinel.go 
func (opt *FailoverOptions) clusterOptions() *ClusterOptions {
	return &ClusterOptions{
                ....
		DB:       opt.DB,
                ....
                ....
	}
}

[Ankit-Kulkarni]

Any updates ?

@SoulPancake @ofekshenawa can anyone of you or other contributors can lookinto this ?

[rosaekapratama]

Any updates regarding this? I got same problem here, need to connect to outside of DB 0 of sentinel

@Ankit-Kulkarni do you change the file urself in local for temp fix?

[Ankit-Kulkarni]

@rosaekapratama yes the above code patch worked for me . i have changed it to local and using it since then.

[davama]

Good day,

Thank you for posting this @Ankit-Kulkarni . Was stumbling on this myself on an application I use. Hoping to hear some updates from the devs

Best

[SoulPancake]

Thanks folks and sorry to miss this

Hi @monkey92t Do you see any problems with this approach https://github.com/redis/go-redis/issues/2824#issue-2031030711