redis-clustr

redis-clustr

This module is a relatively thin wrapper around the node redis client to enable use of Redis Cluster. It tries to be as unobtrusive as possible - mimicing the behaviour of the node_redis client.

Usage

var RedisCluster = require('redis-clustr');

var redis = new RedisCluster({
  servers: [
    {
      host: '127.0.0.1',
      port: 7000
    }
  ]
});

redis.set('key', 'value');

Servers

Servers in the cluster will be automatically connected to (via the response of cluster slots). Of course, to allow discovery there must be at least one server specified in the configuration.

Client creation

By default, clients will be created using Redis.createClient(port, host). This can be overridden by providing a function which must return a node_redis client. Clients are cached so only one connection will be made to each server.

var RedisCluster = require('redis-clustr');
var RedisClient = require('redis');
var redis = new RedisCluster({
  servers: [...],
  createClient: function(port, host) {
    // this is the default behaviour
    return RedisClient.createClient(port, host);
  }
});

Supported functionality

Slot reallocation

Supported - when a response is given with a MOVED error, we will immediately re-issue the command on the other server and run another cluster slots to get the new slot allocations. ASK redirection is also supported - we wil re-issue the command without updating the slots. TRYAGAIN responses will be retried automatically.

Multi / Exec (Batch)

Multi commands are supported but treated as a batch of commands (not an actual multi) and the response is recreated in the original order. Commands are grouped by node and sent as node_redis batches

Multi-key commands (del, mget and mset)

Multi-key commands are also supported and will be split into individual commands (using a batch) then have the response recreated. Only del, mget and mset are supported at the moment.

Errors

Just like node_redis, listen to the error event to stop your application from crashing due to errors. Redis Clustr automatically intercepts connection errors and will try to reconnect to the server.