I want to have more than one Redis client object as multiple DB instance like DB0 (O INDEX REDIS DB).
Currently, I'm using
let RedisClient = require("./redis");
RedisClient.select(1, function (err, res) {
// any operation here
});
so RedisClient is having DB1 instance. what is the best way to deal with multiple db if we want to use another DB2 ?
Use redis.createClient() twice
const redis = require("redis");
const client_1 = redis.createClient(REDIS_1_HOST, REDIS_PORT_1);
const client_2 = redis.createClient(REDIS_2_HOST, REDIS_PORT_2);
see: https://www.npmjs.com/package/redis#rediscreateclient
Related
I'm trying to use Redis in a nextJs API which has a custom express server. I created a util file for Redis in order to connect to the Redis labs, the same way I did with mongodb. The problem is that when I try to use the client.Hset the console keeps sending me errors that econ refused, but I also made sure that when Redis is connected it console logs a string. So the console, logs both the error of econ refused, and the log connected to redis. This is how my util file looks like:
/* ------ connecting to redis ------ */
const redis = require('redis');
const { promisify } = require('util');
const client = redis.createClient({
host: process.env.REDIS_HOSTNAME,
port: process.env.REDIS_PORT,
password: process.env.REDIS_PASSWORD
});
client.on('connect', ()=>{
console.log('connected to redis')
})
/* promisifying redis in order to use async functionality */
const redisHget = promisify(client.hget).bind(client)
const redisHset = promisify(client.hset).bind(client)
module.export = {redisHget, redisHset}
It seems like every time I call the API, it reconnects to Redis. may I know if there is a way I can use redis the same way I use MongoDB by just creating and importing collections so that it doesn't keep reconnecting to the redis labs server?
Lee Robinson (DevRel # Vercel), wrote a nice article about using Redis in Next.js. https://leerob.io/blog/serverless-redis-nextjs.
Complete Example here: https://github.com/vercel/next.js/blob/canary/examples/with-redis/README.md
Snippets:
# env.local
REDIS_URL=redis://:password#endpoint:port
We'll use ioredis, a Node.js Redis client with async/await support, to connect to Redis.
// lib/redis.js
import Redis from 'ioredis';
const redis = new Redis(process.env.REDIS_URL);
export default redis;
Using it, either in pages/ or pages/api/,
import redis from '#/lib/redis';
const value = JSON.parse(await redis.hget('feedback', id));
This is a little hard articulate so I hope my title isn't too terrible.
I have a frontend/backend React/Node.js(REST API) Web app that I want to add Redis support to for storing retrieving app global settings and per-user specific settings (like language preference, last login, etc... simple stuff) So I was considering adding a /settings branch to my backend REST API to push/pull this information from a redis instance.
This is where my Node.js inexperience comes through. I'm looking at using the ioredis client and it seems too easy. If I have a couple of helpers (more than one .js which will call upon redis) will constructing the client as a const in each be safe to do? Or is there another recommended approach to reusing a single instance of it be the way to go?
Here's a sample of what I'm thinking of doing. Imagine if I had 3 helper modules that require access to the redis client. Should I declare them as const in each? Or centralize them in a single helper module, and get the client from it? Is there a dis-advantage to doing either?
const config = require('config.json');
const redis_url = config.redis_url;
//redis setup
const Redis = require('ioredis');
const redis = new Redis(redis_url);
module.exports = {
test
}
async function test(id) {
redis.get(id, function (err, result) {
if (err) {
console.error(err);
throw(err);
} else {
return result;
}
});
Thank you.
If no redis conflicts...
If the different "helper" modules you are referring to have no conflicts when interacting with redis, such as overwriting / using the same redis keys, then I can't see any reason not to use the same redis instance (as outlined by garlicman) and export this to the different modules in which it is used.
Otherwise use separate redis databases...
If you do require separate redis database connections, redis ships with 16 databases so you can specify which to connect to when creating a new instance - see below:
const redis = new Redis({ // SET UP CONFIG FOR CONNECTION TO REDIS
port: 6379, // Redis port
host: 127.0.0.1, // Redis host
family: 4, // 4 (IPv4) or 6 (IPv6)
db: 10, // Redis database to connect to
});
Normally what I would do (in Java say) is implement any explicit class with singleton access the hold the connection and any connection error/reconnect handling.
All modules in Node.js are already singletons I believe, but what I will probably go with will be a client class to hold it and my own access related methods. Something like:
const config = require('config.json');
const Redis = require("ioredis");
class Redis {
constructor(){
client = new Redis(config.redis_url);
}
get(key) {
return this.client.get(key);
}
set(key, value, ttl) {
let rp;
if (ttl === 0) {
rp = this.client.set(key, value);
}
else {
rp = this.client.set(key, value)
.then(function(res) {
this.client.expire(key, ttl);
});
}
return rp;
}
}
module.exports = new Redis;
I'll probably include a data_init() method to check and preload an initial key/value structure on first connect.
When i try to connect my Nodsjs application to RedisCloud on Heroku I am getting the following error
Redis::CannotConnectError: Error connecting to Redis on 127.0.0.1:6379 (ECONNREFUSED)
I have even tried to directly set the redis URL and port in the code to test it out as well. But still, it tried to connect to the localhost on Heroku instead of the RedisCloud URL.
const {Queue} = require('bullmq');
const Redis = require('ioredis');
const conn = new Redis(
'redis://rediscloud:mueSEJFadzE9eVcjFei44444RIkNO#redis-15725.c9.us-east-1-4.ec2.cloud.redislabs.com:15725'
// Redis Server Connection Configuration
console.log('\n==================================================\n');
console.log(conn.options, process.env.REDISCLOUD_URL);
const defaultQueue = () => {
// Initialize queue instance, by passing the queue-name & redis connection
const queue = new Queue('default', {conn});
return queue;
};
module.exports = defaultQueue;
Complete Dump of the Logs https://pastebin.com/N9awJYL9
set REDISCLOUD_URL on .env file as follows
REDISCLOUD_URL =redis://rediscloud:password#hostname:port
import * as Redis from 'ioredis';
export const redis = new Redis(process.env.REDISCLOUD_URL);
I just had a hard time trying to find out how to connect the solution below worked for me.
Edit----
Although I had been passed the parameters to connect to the Redis cloud, it connected to the local Redis installed in my machine. Sorry for that!
I will leave my answer here, just in case anyone need to connect to local Redis.
let express = require('express');
var redis = require('ioredis');
pwd = 'your_pwd'
url = 'rediss://host'
port = '1234'
redisConfig = `${url}${pwd}${port}`
client = redis.createClient({ url: redisConfig })
client.on('connect', function() {
console.log('-->> CONNECTED');
});
client.on("error", function(error) {
console.error('ERRO DO REDIS', error);
});
Just wanted to post my case in case someone has the same problem like me.
In my situation I was trying to use Redis with Bull, so i need it the url/port,host data to make this happened.
Here is the info:
https://devcenter.heroku.com/articles/node-redis-workers
but basically you can start your worker like this:
let REDIS_URL = process.env.REDISCLOUD_URL || 'redis://127.0.0.1:6379';
//Once you got Redis info ready, create your task queue
const queue = new Queue('new-queue', REDIS_URL);
In the case you are using local, meaning 'redis://127.0.0.1:6379' remember to run redis-server:
https://redis.io/docs/getting-started/
Scenario
Using node_redis to build a simple Redis Pubish Subscribe (chat) example: https://github.com/nelsonic/hapi-socketio-redis-chat-example (with Hapi.js and Socket.io)
We have created a node module redis_connection.js in our project ( see: http://git.io/vqaos ) to instantiate the Redis connection because we don't want to be repeating the code which connects (to RedisCloud) multiple times:
var redis = require('redis');
var url = require('url');
var redisURL = url.parse(process.env.REDISCLOUD_URL);
var redisClient = redis.createClient(redisURL.port, redisURL.hostname,
{no_ready_check: true});
redisClient.auth(redisURL.auth.split(":")[1]);
module.exports = redisClient;
Which we then use like this:
var redisClient = require('./redis_connection.js');
// Confirm we are able to connect to RedisCloud:
redisClient.set('redis', 'working', redisClient.print);
redisClient.get('redis', function (err, reply) {
console.log('RedisCLOUD is ' +reply.toString());
});
This works fine for normal GET/SET operations with Redis,
but when we try to instantiate multiple connections to Redis (e.g: one to publish, another to subscribe and a third just to GET/SET keys/values) we get an error:
Issue
We are seeing the following error:
Error: Connection in subscriber mode, only subscriber commands may be used
What are we doing wrong?
Full code at the point where we see this issue: http://git.io/vqa6y
Note
We tried to dig through existing SO Q/A on this, e.g:
Publish subscribe with nodejs and redis(node_redis)
Redis publish/subscribe: see what channels are currently subscribed to
how to use the redis publish/subscribe
but did not find a solution that exactly matched our situation...
(any suggestions/help much appreciated!)
Not tested, but too long for a comment.
Try to define another redis connection module, one for your regular usage and a second one solely for your pubsub subscriptions usage.
Add a redis_pubsub_connection.js to your project:
var redis = require('redis');
var url = require('url');
var redisURL = url.parse(process.env.REDISCLOUD_URL);
var redisPubSubClient = redis.createClient(redisURL.port, redisURL.hostname,
{no_ready_check: true});
redisPubSubClient.auth(redisURL.auth.split(":")[1]);
module.exports = redisPubSubClient;
And change your publish.js require statement to:
var redis = require('./redis_pubsub_connection'); // RedisCloud
redis-connection node.js module
In the interest of keeping this re-useable across our projects we wrote a (mini) node.js module to initialize Redis connections: https://github.com/dwyl/redis-connection
The code is simple and tested and takes care of authentication if required.
(not copy-pasting the module here to avoid duplication)
see: https://github.com/dwyl/redis-connection/blob/master/index.js
Usage:
Install from NPM
npm install redis-connection --save
Use in your script
var redisClient = require('redis-connection')();
redisClient.set('hello', 'world');
redisClient.get('hello', function (err, reply) {
console.log('hello', reply.toString()); // hello world
});
Publish Subscribe
var redisClient = require('redis-connection')(); // Publisher
var redisSub = require('redis-connection')('subscriber');
redisSub.subscribe("chat:messages:latest", "chat:people:new");
For a working example see: https://github.com/dwyl/hapi-socketio-redis-chat-example
The advantage is that we can re-use the same redisClient across multiple files in the same project without creating new connections (the single or pub/sub connection is cached and re-used)
Credit: We borrowed ideas from several places so have up-voted all the answers. But ultimately we wrote a slightly different solution so we have shared it with everyone on NPM/GitHub. Thanks again everyone!
If you want to supply regular connection and a sub one and you want to ensure you only have one of each across the application than you could use a combination of the two solutions that includes the notion of a singleton, something like this:
var subConnection, con;
var createConnection = module.exports.createConnection = function(){
var redis = require('redis');
var url = require('url'); var redisURL = url.parse(process.env.REDISCLOUD_URL);
var redisClient = redis.createClient(redisURL.port, redisURL.hostname, {no_ready_check: true});
redisClient.auth(redisURL.auth.split(":")
return redisClient;
}
module.exports.getSubConnection = function(){
if (!subConnection)
subConnection = createConnection();
return subConnection
}
module.exports.getConnection = function(){
if (!con)
con = createConnection();
return con
}
}
Repeat for the oher two connection types and call it like
var con = require('./redis_connection.js').getConnection();
The problem is that your redis client creation code is being cached by requires so you reuse the same connection again and again. Instead of returning the connection in your redis_connection module, you could return a function:
module.exports = function(){
var redis = require('redis');
var url = require('url'); var redisURL = url.parse(process.env.REDISCLOUD_URL);
var redisClient = redis.createClient(redisURL.port, redisURL.hostname, {no_ready_check: true});
redisClient.auth(redisURL.auth.split(":")
return redisClient;
}
And then call it like so:
var redisClient = require('./redis_connection.js')();
I am working on a complex game with Nodejs and Socket.io, where I need to store socket.io objects in the memory and also assign properties to the socket object ( say a name , a counter of some action from the socket , etc )
In the code below, I have shown an example of what I am trying to achieve. I store all the sockets in an array and also have another array which stores the name property of the socket.
At any time if I get a request for the name, I can just pick the name from the array in the memory.
But now I have too many users and I need to load-balance my application across multiple servers. So I cant store objects and properties in the memory. I need to store them in a Database.
I am planning to use Redis. This link tells how to use Redis Store for sockets -
https://github.com/LearnBoost/Socket.IO/wiki/Configuring-Socket.IO
But how do I associate my other properties ( say name etc ) to the socket object in the Redis Store ? If there is some new ways to achieve this , please let me know also.
var socket_array = new Array();
var socket_name_array = new Array();
var io = require('socket.io').listen(80);
io.sockets.on('connection', function (socket) {
socket_array.push(socket);
var i = socket_array.indexOf(socket);
var name = generate_random_name();
socket_name_array[i]= name;
socket.on('get_name', function (data) {
var i = socket_array.indexOf(socket);
var name= socket_name_array[i]
socket.emit('socket_name' , {name :name } );
});
});
function generate_random_name(){
var random_string;
//code
return random_string;
}
Yes, if you want to load balance socket.io servers you will have to use a store like redisstore.
However now you should not use "socket_name_array" + events to maintain data consistent across your server.
Setup
var redis = require('redis'),
var pub = redis.createClient(port, host),
var sub = redis.createClient(port, host),
var client = redis.createClient(port, host);
io.configure(function(){
io.set('store', new RedisStore({
redisPub: pub,
redisSub : sub,
redisClient : client
}));
});
Usage
io.sockets.on('connection', function (socket) {
var name = generate_random_name();
socket.set('name', name); // store it in redis and forward this to other socket.io servers
// On another server, if you want to retrieve this value from this socket just do:
socket.get('name', function(err, name){
// don't forget err. handling
console.log(name);
});
});