Connection to Redis cluster failed

Question

I have setup Redis cluster in Google compute Engine by click to deploy option. Now i want to connect to this redis server from my node js code using 'ioredis' here is my code to connect to single instance of redis

var Redis = require("ioredis");

var store = new Redis(6379, 'redis-ob0g');//to store the keys
var pub =   new Redis(6379, 'redis-ob0g');//to publish a message to all workers
var sub =   new Redis(6379, 'redis-ob0g');//to subscribe a message 

var onError = function (err) {
    console.log('fail to connect to redis ',err);
};
store.on('error',onError);
pub.on('error',onError);
sub.on('error',onError);

And it worked. Now i want to connect to redis as cluster, so i change the code as

/**
 * list of server in replica set
 * @type {{port: number, host: string}[]}
 */
var nodes =[
    {   port: port,    host: hostMaster},
    {   port: port,    host: hostSlab1},
    {   port: port,    host: hostSlab2}
];
var store =  new Redis.Cluster(nodes);//to store the keys
var pub =   new Redis.Cluster(nodes);//to publish a message to all workers
var sub =    new Redis.Cluster(nodes);//to subscribe a message channel

Now it throw this error:

Here is my Redis cluster in my google compute console:

Answer 1

Ok, I think there is a confusion here.

A Redis Cluster deployment is not the same than a number of standard Redis instances protected by Sentinel. Two very different things.

The click-to-deploy option of GCE deploys a number of standard Redis instances protected by Sentinel, not Redis Cluster.

ioredis can handle both kind of deployments, but you have to use the corresponding API. Here, you were trying to use the Redis Cluster API, resulting in this error (cluster related commands are not activated for standard Redis instances).

According to ioredis documentation, you are supposed to connect with:

var redis = new Redis({
    sentinels: [{ host: hostMaster, port: 26379 },
                { host: hostSlab1, port: 26379 },
                { host: hostSlab2, port: 26379 } ],
    name: 'mymaster'
});

Of course, check the sentinel ports and name of the master. ioredis will manage automatically the switch to a slave instance when the master fails, and sentinel will ensure the slave is promoted as master just before.

Note that since you use pub/sub, you will need several redis connections.