Redis To Go

Last Updated: 19 January 2012

java python redis redistogo

Using Redis from Ruby
Using Redis from Java
Using Redis from Python
Deploying to Heroku
Other Resources

Redis is a key-value store similar to memcached, but non-volatile; it supports lists, hashes, sets, and ordered sets.

Using Redis from Ruby

Gem Setup

The redis-rb client is the easiest way to access Redis from Ruby. Install redis-rb with sudo gem install redis.

Using from Rails

For Rails 2.3.3 and higher, update the config/environment.rb to include the redis gem.

config.gem 'redis'

If using Rails 3, update the Gemfile:

gem 'redis'

Setup the Redis connection information for development in config/environments/development.rb

ENV["REDISTOGO_URL"] = 'redis://username:password@my.host:6789'

Configure Redis in config/initializers/redis.rb

uri = URI.parse(ENV["REDISTOGO_URL"])
REDIS = Redis.new(:host => uri.host, :port => uri.port, :password => uri.password)

Test that it works in the console.

$ rails console
>> REDIS.set("foo", "bar")
"OK"
>> REDIS.get("foo")
"bar"

Using from Sinatra

In the configure block include:

configure do
  require 'redis'
  uri = URI.parse(ENV["REDISTOGO_URL"])
  REDIS = Redis.new(:host => uri.host, :port => uri.port, :password => uri.password)
end

Test that it works in the console.

$ irb -r myapp.rb
>> REDIS.set("foo", "bar")
"OK"
>> REDIS.get("foo")
"bar"

Using Redis from Java

There are several Java libraries available for connecting to Redis, including Jedis and JRedis. This guide will shows to use Jedis from both a generic Java application and a Spring configured application.

Add Jedis to Dependencies

Include the Jedis library in your application by adding the following dependency to pom.xml:

<dependency>
    <groupId>redis.clients</groupId>
    <artifactId>jedis</artifactId>
    <version>2.0.0</version>
</dependency>

Use Redis in your application

The connection information for the Redis Service provisioned by Redis To Go is stored as a URL in the REDISTOGO_URL config var. You can create a Jedis connection pool from this URL string with the following code snippet:

try {
    URI redisURI = new URI(System.getenv("REDISTOGO_URL"));
    JedisPool pool = new JedisPool(new JedisPoolConfig(),
            redisURI.getHost(),
            redisURI.getPort(),
            Protocol.DEFAULT_TIMEOUT,
            redisURI.getUserInfo().split(":",2)[1]);
} catch (URISyntaxException e) {
    // URI couldn't be parsed. Handle exception
}

Now you can use this pool to perform Redis operations. For example:

Jedis jedis = pool.getResource();
try {
  /// ... do stuff here ... for example
  jedis.set("foo", "bar");
  String foobar = jedis.get("foo");
  jedis.zadd("sose", 0, "car"); jedis.zadd("sose", 0, "bike"); 
  Set<String> sose = jedis.zrange("sose", 0, -1);
} finally {
  /// ... it's important to return the Jedis instance to the pool once you've finished using it
  pool.returnResource(jedis);
}

(example taken directly from Jedis docs).

Using Redis with Spring

Use the following Java Configuration class to set up a JedisPool instance as a singleton Spring bean:

@Configuration
public class SpringConfig {

        @Bean
        public JedisPool getJedisPool() {
                try {
                        URI redisURI = new URI(System.getenv("REDISTOGO_URL"));
                        return new JedisPool(new JedisPoolConfig(),
                                        redisURI.getHost(),
                                        redisURI.getPort(),
                                        Protocol.DEFAULT_TIMEOUT,
                                        redisURI.getUserInfo().split(":",2)[1]);
                } catch (URISyntaxException e) {
                        throw new RuntimeException("Redis couldn't be configured from URL in REDISTOGO_URL env var:"+ 
                                                    System.getenv("REDISTOGO_URL"));
                }
        }

}

or the following XML configuration file:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd">

<context:annotation-config/>
<context:property-placeholder/>

<bean id="jedisURI" class="java.net.URI">
    <constructor-arg value="${REDISTOGO_URL}"/>
</bean>
<bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig"/>
<bean id="jedisPool" class="redis.clients.jedis.JedisPool">
    <constructor-arg index="0" ref="jedisPoolConfig"/>
    <constructor-arg index="1" value="#{ @jedisURI.getHost() }"/>
    <constructor-arg index="2" value="#{ @jedisURI.getPort() }"/>
    <constructor-arg index="3" value="#{ T(redis.clients.jedis.Protocol).DEFAULT_TIMEOUT }"/>
    <constructor-arg index="4" value="#{ @jedisURI.getUserInfo().split(':',2)[1] }"/>
</bean>
</beans>

Sample code

To see a complete, working example, check out the sample code in github. The readme explains more about the example.

Using Redis from Python

The redis-py client is the easiest way to access Redis from Python. Install redis-py with pip install redis.

Using from Python

import os, urlparse
if os.environ.has_key('REDIS_TO_GO'):
    urlparse.uses_netloc.append('redis')
    url = urlparse.urlparse(os.environ['REDIS_TO_GO'])
    REDIS = redis.Redis(host=url.hostname, port=url.port, db=0, password=url.password)

Using as a Django Cache

import os, urlparse
if os.environ.has_key('REDIS_TO_GO'):
    urlparse.uses_netloc.append('redis')
    url = urlparse.urlparse(os.environ['REDIS_TO_GO'])

CACHES = {
    'default': {
        'BACKEND': 'redis_cache.RedisCache',
        'LOCATION': '%s:%s' % (url.hostname, url.port),
        'OPTIONS': {
            'DB': 0,
            'PASSWORD': url.password,
            'PARSER_CLASS': 'redis.connection.HiredisParser'
        },
    },
}

Deploying to Heroku

To use Redis To Go on Heroku, install the redistogo add-on:

$ heroku addons:add redistogo

Test that it works from the Heroku console:

$ heroku console
>> REDIS.set("answer", 42)
"OK"
>> REDIS.get("answer")
42

Heroku