Redis Connection

A Global Redis Connection that can be used anywhere in your app and closed once at the end of tests.

Why?

At dwyl we use Redis everywhere because its fast!

If you're new to Redis, checkout our beginners tutorial: https://github.com/dwyl/learn-redis

Given that Redis can handle millions of operations per second, it is unlikely to be the bottleneck in your application/stack.

Where you can (unintentionally) create an issue is by having too many connections to your Redis Datastore. Don't laugh, we've seen this happen, where people open a new connection to Redis for each incoming http request (and forget to close them!) and thus quickly run out of available connections to Redis!

Most apps really only need one connection to Redis (per node.js instance) Or, if you are using Redis' Publish/Subscribe feature, you will need two connections per node.js server; one for a "standard" connection (the "Publisher"") and another as a "Subscriber".

Given that we modularise our apps and we don't want each file opening multiple connections to the Redis datastore (because Redis connections are a scarce resource - e.g: RedisCloud is 30 connections - and each connection needs to be closed for tape tests to exit...) we decided write a little script to instantiate a single connection to Redis which can be re-used across multiple files.

What?

An easy way to re-use your single Redis connection (or pair of connections - when using Redis Publish/Subscribe) across multiple files/handlers in your application and close once at the end of your tests.

How?

Install from NPM

npm install redis-connection --save

Use in your code

var redisClient = require('redis-connection')(); // require & connect
redisClient.set('hello', 'world');
redisClient.get('hello', function (err, reply) {
  console.log('hello', reply.toString()); // hello world
});

Using Redis Publish / Subscriber ?

You can use the standard redisClient for publishing but will need to have a separate connection to subscribe on.

Create a Subscriber connection by supplying the word subscriber when starting the redis-connection:

var redisSub = require('redis-connection')('subscriber');
redisSub.subscribe("chat:messages:latest", "chat:people:new");
// see: https://github.com/dwyl/hapi-socketio-redis-chat-example ;-)

Closing your Connection(s)

Closing your connections is easy.

var redisClient = require('redis-connection')(); // require & connect
redisClient.set('hello', 'world');
redisClient.get('hello', function (err, reply) {
  console.log('hello', reply.toString()); // hello world
  redisClient.end(true); // this will "flush" any outstanding requests to redis
});

If you have created multiple connections in your app (you would do this to use Redis' Publish/Subscribe feature), we have a simple method to "Close All" the connections you have opened in a single command: killall()

e.g:

var redisClient = require('redis-connection')(); // require & connect
var redisSub = require('redis-connection')('subscriber');

// do things with redisClient and redisSub in your app...
// when you want to close both connections simply call:
require('redis-connection').killall();

Using redis-connection with env2

If you are using env2 to load your configuration file, simply require env2 before requiring redis-connection:

require('env2')('.env'); // load the redis URL
var redisClient = require('redis-connection')();
// now use your redis connection

Make sure you have defined an environment variable named "REDIS_URL" or "REDISCLOUD_URL" For example:

REDIS_URL=redis://127.0.0.1:6379/0

If the REDIS_URL (or REDISCLOUD_URL) environment variable is not defined redis-connection will use the Redis localhost url (127.0.0.1) on the port 6379

Need More?

If you need us to support a different Redis-as-a-service provider or want to have more configuration options, please let us know!

Contributors

As with all @dwyl projects

Environment Variables

If you want to help improve/update/extend this module, please ask us for access to the environment variables (.env file) with REDISCLOUD_URL so you can test your modifications locally.

Failed Connection ?

If you are seeing a "Redis Connection Error" message in your terminal, e.g:

- - - - - - - - Redis Connection Error: - - - - - - - -
{ Error: 'Redis connection to 127.0.0.1:6380 failed',
  code: 'ECONNREFUSED',
  errno: 'ECONNREFUSED',
  syscall: 'connect',
  address: '127.0.0.1',
  port: 4321 }
- - - - - - - - - - - - - - - - - - - - - - - - - - - -

Either your local instance of Redis is not running or is running on a different port from the standard which is 6379. Confirm Redis is running then try again!