Redis To Go

Last Updated: 18 March 2014

java python redis redistogo

RedisToGo is an add-on for providing functionality for Redis with graphs, backups, persistence and fine-tuned Redis. We currently support over 37,000 Redis instances, we’re here to help you rock your app with Redis goodness.

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

Adding Redis to an application provides benefits, you may be using RedisToGo to power simple Resque or Sidekiq jobs, or using the raw power of Redis 2.6 Lua Scripting to do some crazy fast operations. Redis can be used a database, but it’s often used as a complementary datastore. With over 140 commands, the possibilities are endless.

RedisToGo is accessible via an API and has supported client libraries for Java, Ruby, Python, Node.js, Clojure, GoLang.

Provisioning the add-on

RedisToGo can be attached to a Heroku application via the CLI:

$ heroku addons:add redistogo
-----> Adding RedisToGo to fat-unicorn-1337... done, v18 (free)

Once RedisToGo has been added a ADDON_CONFIG_NAME setting will be available in the app configuration. This can be confirmed using the heroku config:get command.

$ heroku config --app fat-unicorn-1337 | grep REDISTOGO_URL
REDISTOGO_URL              => redis://redistogo:44ec0bc04dd4a5afe77a649acee7a8f3@drum.redistogo.com:9092/

After installing RedisToGo the application should be configured to fully integrate with the add-on.

Using with Rails 2.3.3

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:6389'

Configure Redis in config/initializers/redis.rb for versions before Rails 4

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

If you are running Rails 4 then run the following

uri = URI.parse(ENV["REDISTOGO_URL"])
REDIS = Redis.new(:url => ENV['REDISTOGO_URL'])

Test that it works in the console.

$ rails console
>> 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 Java 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 Java code

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

Install Redis in Python

The redis-py module is the best way to access Redis from Python.

To install it, use pip:

$ pip install redis

And to have your application depend on it, add the following to requirements.txt:

$ pip freeze | grep redis
redis==2.4.13

Using from Python

Example store.py:

import os
import redis

redis_url = os.getenv('REDISTOGO_URL', 'redis://localhost:6379')
redis = redis.from_url(redis_url)

Using with bottlepy

redistogo_url = os.getenv('REDISTOGO_URL', None) if redistogo_url == None: redis_url = '127.0.0.1:6379' else: redis_url = redistogo_url redis_url = redis_url.split('redis://redistogo:')[1] redis_url = redis_url.split('/')[0] REDIS_PWD, REDIS_HOST = redis_url.split('@', 1) redis_url = "%s?password=%s" % (REDIS_HOST, REDIS_PWD) session_opts = { 'session.type': 'redis', 'session.url': redis_url, 'session.data_dir': './cache/', 'session.key': 'appname', 'session.auto': True, }

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 run python
Python 2.7.2 (default, Oct 31 2013, 16:22:04)
>>> from store import redis
>>> redis.set('answer', 42)
True
>>> redis.get('answer')
'42'

Using as a Django cache

Redis can also be used with the Django cache backend.

To do so, install the Django :

$ pip install django-redis-cache

Then, add the following to your settings.py file:

import os
import urlparse

redis_url = urlparse.urlparse(os.environ.get('REDISTOGO_URL', 'redis://localhost:6959'))

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

Using with Node.

When node_redis connects to a Redis instance on your local machine it assumes the default port and host information, so instantiating the client is as simple as this:

var redis = require("redis").createClient();

That works just fine in development, but we need it to authenticate to Redis To Go in production. To handle both cases I just check for the existence of the REDISTOGO_URL, like so:

if (process.env.REDISTOGO_URL) {
    // TODO: redistogo connection
} else {
    var redis = require("redis").createClient();
}

Everything should still work fine in development, but we still need to implement the Redis To Go connection. To do this we need to extract the port, hostname, and authentication string from REDISTOGO_URL using Node’s built-in url lib:]

// inside if statement
var rtg   = require("url").parse(process.env.REDISTOGO_URL);
var redis = require("redis").createClient(rtg.port, rtg.hostname);

redis.auth(rtg.auth.split(":")[1]);

For some reason Node’s url lib won’t split up the auth section’s username and password, so that’s what is going on in the rtg.client.auth.split(":")[1] that is passed to the auth command.

Redis-related entries I have in my package.json are hiredis (0.1.10) and redis (0.6.0).

GoLang

We recommend using redigo to connect to RedisToGo.

Redis 2.6 & 2.8

RedisToGo runs with 2.4 as default, but if you need 2.6 or 2.8 drop us a line and we’ll get you set up. We currently offer this to all paid accounts. Please contact Support@RedisToGo.com.

Lua

Lua is the business. In short Lua lets you run application code on the server.

Redis Sentinel

We can offer Redis Sentinel configured HA environments for high volume accounts. Please contact support@redistogo.com for more information and a consultation.

Monitoring & Logging

We offer monitoring and logging on a per account basis. We’ll inform our customers when they start to reach memory and connection limits.

If you’re using Redis for resque we recommend using Airbrake, please read this blog post for more instructions on setting up error

Dashboard

The RedisToGo dashboard allows you to view config, display graphs, retrieve backups.

The dashboard can be accessed via the CLI:

$ heroku addons:open redistogo
Opening RedisToGo for fat-unicorn-1337…

or by visiting the Heroku apps web interface and selecting the application in question. Select RedisToGo from the Add-ons menu.

Troubleshooting

Why am I hitting my connection limit with one Dyno? This is often caused by customers using the nano free plan. One connection is used by one worker, but often other connections can be made to Redis. We would recommend upgrading to our lowest plan to see if this solves the issue. Otherwise we would recommend setting a hard limit on your application code.

Migrating between plans

WARNING: Upgrades from ‘nano’ to Mini will loose data. If you would like to keep data please e-mail support@redistogo.com

Use the heroku addons:upgrade command to migrate to a new plan.

$ heroku addons:upgrade redistogo:mini
-----> Upgrading RedisToGo:newplan to fat-unicorn-1337... done, v18 ($49/mo)
       Your plan has been updated to: RedisToGo:newplan

This may fail if the server is full, if this happens please e-mail support@redistogo.com and we can help you out.

Removing the add-on

RedisToGo can be removed via the CLI.

$ heroku addons:remove redistogo
-----> Removing RedisToGo from fat-unicorn-1337... done, v20 (free)

Before removing RedisToGo a data export can be performed by going to the backups tab of RedisToGo https://redistogo.com/heroku/resources/[instance-ID]/backups this will offer a download a .rdb, backup file.

Support

All RedisToGo support and runtime issues should be submitted via on of the Heroku Support channels. We recommend CC:ing support@redistogo.com for urgent issues.

We are available on twitter, and you can call us (855) 733 4786.

Urgent. Call Morgan.

Morgan is the support king-pin. He’s around Pacific business hours to take calls; talk about your Redis instance, craft coffee and who would win in a battle between unicorns and badgers.

Call him today on (855) 733 4786, we’re here to help and chat.

Other resources

• Intro to Redis
• Exporting Data
• Resque
• Resque Scheduler
• Node.js with Pub Sub
• Other Documentation
• Follow @redistogo