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Add Redis to Your Application

Redis is an open source, advanced key-value store. It is often referred to as a data structure server because keys can contain strings, hashes, lists, sets, and sorted sets.

This page describes getting Redis working on your Engine Yard Cloud application.

Install Redis on a utility instance

To install Redis you'll need to use a custom Chef recipe; for more information about custom Chef recipes, see Custom Chef recipes.

Note: You should only have one Redis install per environment. Engine Yard does not recommend installing Redis on your application instances because it can cause complications. For example, if you have more than one app instances, installing Redis on those instances can result in multiple Redis versions on your app servers. If you install it only on your application master, it will likely get overloaded.

Here is a procedure for adding Redis to a utility instance named “redis”. You’ll need to adjust this procedure for your specific environment.

To install Redis on a utility instance

  1. Download the ey-cloud-recipes to your local computer.

    $ git clone https://github.com/engineyard/ey-cloud-recipes.git 
  2. Uncomment require_recipe "redis" from the main cookbook (main/recipes/default.rb).

  3. Add a utility instance named “redis” to your application.

  4. Upload and apply the recipes to your environment:

    $ ey recipes upload -e <environment_name> 
    $ ey recipes apply -e <environment_name>

To connect to Redis on the utility instance from your Rails application

Here is a link to a Gist that will write out a redis.yml configuration file. You can then connect to Redis in an initializer or environment file using the following:

# Load the redis.yml configuration file 
redis_config = YAML.load_file(Rails.root + 'config/redis.yml')[Rails.env]

# Connect to Redis using the redis_config host and port
if redis_config
$redis = Redis.new(host: redis_config['host'], port: redis_config['port'])

Install the Redis gem

First, you need to bundle the Redis gem into your application.

To add Redis to your application

  1. Add the Redis gem to your gemfile.
    gem ‘redis’
  2. Install the Redis gem using bundler from your development machine.
    bundle install
  3. Deploy your application.

Update the Redis version

To upgrade to a newer version of Redis pull the latest changes to the Redis custom Chef recipe into your fork from upstream, or edit the install version within your existing recipe. Upload and apply this recipe update; to complete the upgrade you will need to restart Redis (we do not recommend adding the restart to the chef Recipe).

To find out your Redis version

  1. Via SSH, connect to the Utility instance that runs your Redis service.

  2. Type:

  3. At the Redis prompt, type:

    redis> info

    The response shows the version number on the first line:

  4. If your version is older that the recommended version (see Engine Yard Technology Stack), follow the procedure below to update the Redis version.

To update Redis

  1. Via SSH, connect to the Utility instance that runs your Redis service.

  2. Type:

    sudo monit restart redis

Things to do with Redis

You can use Redis:

More information

For more information about...See...
Resque and Redis                                                                                    Configure and deploy Resque.                                                                        
SSHing into an instance Connect to your instance via SSH.
Using Redis with Unicorn Customize Unicorn.

If you have feedback or questions about this page, add a comment below. If you need help, submit a ticket with Engine Yard Support.

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  • Avatar
    Petteri Räty

    The documented command to restart Redis did not work for me when upgrading. The command that does the trick is:

    monit restart redis

    /etc/init.d/redis does not work because the Engine Yard stack controls redis through monit. When running the init script baselayout is not aware that redis is already running and just tries to start the daemon. This fails because redis is already running and in control of port 6379:

    tail  /var/log/redis/redis.log                                                                                                                                                                     

    [23616] 06 May 23:27:39 # Opening port 6379: bind: Address already in use

  • Avatar
    Petteri Räty

    If you are running your application with unicorn you should customize your unicorn configuration to reconnect the clients after forking. Instructions for setting up a custom configuration can be found here:


    If you don't do this you might stumble upon an error like:

    Redis::ProtocolError: Got '2' as initial reply byte. If you're running in a multi-threaded environment, make sure you pass the :thread_safe option when initializing the connection. If you're in a forking environment, such as Unicorn, you need to connect to Redis after forking.

  • Avatar
    John Yerhot

    Hi Petteri,

    Great additions, I'll make sure our documentation gets updated with these.



  • Avatar
    Keri Meredith

    Hi Petteri, thanks again for your feedback on our documentation. This page has been updated. kjm

  • Avatar
    Petteri Räty

    Keri: There is a problem with the link at the bottom for: "Using Redis with Unicorn Customize Unicorn." The problem is that redis information has not been added to the Customize Unicorn page yet.


  • Avatar
    Keri Meredith

    Hi Petteri, we are working through these docs - stay tuned! thanks, kjm

  • Avatar
    Krasimir Angelov


    Where can we see the docs related to using Redis with Unicorn on EY? This info is still missing from https://support.cloud.engineyard.com/entries/20996656-customize-unicorn.

  • Avatar
    Jacob Burkhart

    EY automatically installs and runs a redis instance on the DB master. &It's not replicated, monitored, or backed-up, but it will work if you want something simple. (like for caching, or a staging environment)

    Here's the code snippet I use to talk to redis:

    if dbhost = ActiveRecord::Base.connection.instance_variable_get(:@config)[:host]

      REDIS = Redis.connect(:url => "redis://#{dbhost}")


      REDIS = Redis.connect(:url => "redis://")


  • Avatar
    Zhen Yin

    Adding back a comment, posted by Hernus Carelsen earlier :

    "Regarding Jacob's comment above about the out-of-the-box redis instance running on the db server by default, and how to connect to it. I think this is a crucial bit of info that should be included in the document. Furthermore I assume Redis.connect and Redis.new are the same thing?"

  • Avatar
    Arturo Simon

    The section on "To connect to Redis on the utility instance from your Rails application" needs an update for sure.

    Luckily Jacob's comment above saved me.


    $redis = Redis.new(host: redis_config['host'], port: redis_config['port'])


    $redis = Redis.new(url: "redis://#{redis_config['host']}:#{redis_config['port']}")

  • Avatar
    Vitali Mogilevsky

    Found better solution for using app + database instances
    engineyard runs redis on database instance by default, so in order to use it simply add

    db_config = Rails.configuration.database_configuration
    $redis = Redis.new(host: db_config[Rails.env]["host"])

    in your application.rb , its better because it uses database.yml configuration directly
    allowing you to configure cache_store

    config.cachestore = :redis_store, {
    :host => db_config[Rails.env]["host"],
    :port => 6379,
    :namespace => "cache"
    and it will work on your local configuration also, if you run redis locally

  • Avatar
    Tyler Poland

    With the introduction of v5 of the Engine Yard stack we have deprecated the default installation of Redis on Database servers. While this was operational for services with minimal needs it was found to be unreliable and could negatively impact the performance of the main database when the needs of the Redis service expanded. If this installation method is effective for your needs the existing Chef recipe can still be modified to install Redis as before but you should be aware that the services may conflict over resources in this configuration.

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