Getting started with Golang Redis

Installation

go-redis supports 2 last Go versions and only works with Go modulesopen in new window. So first you need to initialize a Go module:

go mod init github.com/my/repo

If you are using Redis 6, install go-redis/v8:

go get github.com/go-redis/redis/v8

If you are using Redis 7, install go-redis/v9 (currently in beta):

go get github.com/go-redis/redis/v9

Connecting to Redis Server

To connect to a Redis Server:

import "github.com/go-redis/redis/v8"

rdb := redis.NewClient(&redis.Options{
	Addr:	  "localhost:6379",
	Password: "", // no password set
	DB:		  0,  // use default DB
})

Another popular way is using a connection string:

opt, err := redis.ParseURL("redis://<user>:<pass>@localhost:6379/<db>")
if err != nil {
	panic(err)
}

rdb := redis.NewClient(opt)

Using TLS

To enable TLS/SSL, you need to provide an empty tls.Config. If you're using private certs, you need to specifyopen in new window them in the tls.Config.

rdb := redis.NewClient(&redis.Options{
	TLSConfig: &tls.Config{
		MinVersion: tls.VersionTLS12,
		//Certificates: []tls.Certificate{cert}
	},
})

If you are getting x509: cannot validate certificate for xxx.xxx.xxx.xxx because it doesn't contain any IP SANs, try to set ServerName option:

rdb := redis.NewClient(&redis.Options{
	TLSConfig: &tls.Config{
		MinVersion: tls.VersionTLS12,
		ServerName: "your.domain.com",
	},
})

Over SSH

To connect over SSH channel:

sshConfig := &ssh.ClientConfig{
	User:			 "root",
	Auth:			 []ssh.AuthMethod{ssh.Password("password")},
	HostKeyCallback: ssh.InsecureIgnoreHostKey(),
	Timeout:		 15 * time.Second,
}

sshClient, err := ssh.Dial("tcp", "remoteIP:22", sshConfig)
if err != nil {
	panic(err)
}

rdb := redis.NewClient(&redis.Options{
	Addr: net.JoinHostPort("127.0.0.1", "6379"),
	Dialer: func(ctx context.Context, network, addr string) (net.Conn, error) {
		return sshClient.Dial(network, addr)
	},
	// Disable timeouts, because SSH does not support deadlines.
	ReadTimeout:  -1,
	WriteTimeout: -1,
})

dial tcp: i/o timeout

You get dial tcp: i/o timeout error when go-redis can't connect to the Redis Server, for example, when the server is down or the port is protected by a firewall. To check if Redis Server is listening on the port, run telnet command on the host where the go-redis client is running:

telnet localhost 6379
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused

If you use Docker, Istio, or any other service mesh / sidecar, make sure the app starts after the container is fully available, for example, by configuring healthchecksopen in new window with Docker and holdApplicationUntilProxyStarts with Istio.

Context

Every Redis command accepts a context that you can use to set timeouts or propagate some information, for example, tracing context.

ctx := context.Background()

Executing commands

To execute a command:

val, err := rdb.Get(ctx, "key").Result()
fmt.Println(val)

Alternatively you can save the command and later access the value and the error separately:

get := rdb.Get(ctx, "key")
fmt.Println(get.Val(), get.Err())

Executing unsupported commands

To execute arbitrary/custom command:

val, err := rdb.Do(ctx, "get", "key").Result()
if err != nil {
	if err == redis.Nil {
		fmt.Println("key does not exists")
		return
	}
	panic(err)
}
fmt.Println(val.(string))

Do returns a Cmdopen in new window that has a bunch of helpers to work with interface{} value:

// Text is a shortcut for get.Val().(string) with proper error handling.
val, err := rdb.Do(ctx, "get", "key").Text()
fmt.Println(val, err)

The full list of helpers:

s, err := cmd.Text()
flag, err := cmd.Bool()

num, err := cmd.Int()
num, err := cmd.Int64()
num, err := cmd.Uint64()
num, err := cmd.Float32()
num, err := cmd.Float64()

ss, err := cmd.StringSlice()
ns, err := cmd.Int64Slice()
ns, err := cmd.Uint64Slice()
fs, err := cmd.Float32Slice()
fs, err := cmd.Float64Slice()
bs, err := cmd.BoolSlice()

redis.Nil

go-redis exports the redis.Nil error and returns it whenever Redis Server responds with (nil). You can use redis-cli to check what response Redis returns.

In the following example we use redis.Nil to distinguish an empty string reply and a nil reply (key does not exist):

val, err := rdb.Get(ctx, "key").Result()
switch {
case err == redis.Nil:
	fmt.Println("key does not exist")
case err != nil:
	fmt.Println("Get failed", err)
case val == "":
	fmt.Println("value is empty")
}

GET is not the only command that returns nil reply, for example, BLPOP and ZSCORE can also return redis.Nil.

Conn

Conn represents a single Redis connection rather than a pool of connections. Prefer running commands from Client unless there is a specific need for a continuous single Redis connection.

cn := rdb.Conn(ctx)
defer cn.Close()

if err := cn.ClientSetName(ctx, "myclient").Err(); err != nil {
	panic(err)
}

name, err := cn.ClientGetName(ctx).Result()
if err != nil {
	panic(err)
}
fmt.Println("client name", name)

See also