Building a user ranking system with Redis

We want to be able to rank users based on how many games they have completed. We will create a user service, implemented in Redis, that provides the following functionality:

• Record when a user successfully completes a game

• Return the top three users across the site

• Return the rank of a given user

We will first add a feature to make the site a bit more user-friendly by allowing users to choose a screen name.

Using Redis from Node.js

First, we'll need to install a Node.js client library for Redis. We'll also use the promise library Bluebird to convert the Redis client library to promises:

> npm install redis --save
> npm install bluebird --save

First, we'll create a module for configuring the Redis client as shown here in src/config/redis.js:

'use strict';

const bluebird = require('bluebird');
const redis = require('redis');
bluebird.promisifyAll(redis.RedisClient.prototype);
module.exports = redis.createClient(process.env.REDIS_URL);

Now we can create...