Roth Roth -4 years ago 94
Node.js Question

How to create a Redis connection with Master and Slave

I am trying to do a Redis connection, I have a "master" port and two slaves. I want to do this with a Sentinel.

My actually code to connect redis is actually deprecated, I think so.

Here is my code.

var redis = require('redis');
var client = redis.createClient(config.redis_port, config.redis_host,
{no_ready_check: true});

if (config.redis_password != null) {
client.auth(config.redis_password, function (err) {
if (err) throw err;
});
}

client.on('connect', function(err, res) {
logger.info('Connected to Redis ' + process.pid);
redisIsReady = true;
});

client.on('error', function(err) {
logger.error('Error connecting to Redis ' + process.pid);
redisIsReady = false;
});

client.get(objectRequest.customerId, function(err, reply) {
if (reply != null && reply >= config.max_requests) {
var json = JSON.stringify({errorCode: validationErrors.TOO_MANY_REQUEST,
description: errorMessage[validationErrors.TOO_MANY_REQUEST]});
res.setHeader('Retry-After', config.retry_after);
res.setHeader('Content-Type', 'application/json');
res.setHeader('Content-Length', json.length);
res.writeHead(429);
res.write(json);
return res.end();
}
// Set a value with an expiration
client.incr(objectRequest.customerId);
client.expire(objectRequest.customerId, config.retry_after);
});


I am reading on others posts and I think that maybe will be cool do it with ioredis. But I dont know much about Redis...

I want to do a connection to redis and if the master is down, this automatically connect to slave.

I hope you help me,

Roth.

Answer Source

I finally got it done and it works nice.

I will let you here my code, I hope this helps others!

var Redis = require('ioredis');
// preferredSlaves array format
var preferredSlaves = [
  { ip: config.redis_slave_1, port: config.redis_port, prio: 1 },
  { ip: config.redis_slave_2, port: config.redis_port, prio: 2 }
];
var redis = new Redis({
  port: config.redis_port,
  host: config.redis_host,
  sentinels: [{ host: config.redis_sentinel_1, port: config.redis_sentinel }, { host: config.redis_sentinel_2, port: config.redis_sentinel }, { host: config.redis_sentinel_3, port: config.redis_sentinel }],
  name: config.redis_master_name,
  password: config.redis_password,
  preferredSlaves: preferredSlaves
});

redis.on('connect', function(err, res) {
  logger.info('Connected to Redis ' + process.pid);
  redisIsReady = true;
  console.log('Connected to Redis ' + process.pid + " REDIS " + JSON.stringify(redis.options) )
});

redis.on('error', function(err) {
  logger.error('Error connecting to Redis ' + process.pid);
  redisIsReady = false;
  console.log('error to Redis ' + err)
});

Thanks for all your responses,

Regards!!

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