Delayed Job recipe for EY Cloud

This cookbook can serve as a good starting point for setting up Delayed Job support in your application. In this recipe your Delayed Job workers will be set up to run under monit. The number of workers will vary based on the size of the instance running Delayed Job.

This recipe will setup delayed_job on a Solo instance environment or on named Utility instances in a cluster environment.

Name your Utility instances with prefixes: dj, delayed_job, delayedjob. For example, dj1, delayedjob4.

If you want delayed_job to run on App instances instead of Utility, you will need to modify the recipe.

TODO: if no corresponding dj|delayed_job|delayedjob named Utility instances, then install DJ on the app instances.

How many workers do I get?

The number of parallel workers is based on the instance type.

Solo instances allocate a single Delayed Job worker because the instance is primarily for running the Application and its database.

For each dj utility instance the number of workers is determined by the delayed_job_worker_count library helper:

def delayed_job_worker_count(instance_type)
  case instance_type
  when "m1.small"
    3
  when "m1.medium"
    4
  when "m1.large"
    8
  when "m1.xlarge"
    12
  when "m2.xlarge"
    10
  when "m2.2xlarge"
    10
  when "m2.4xlarge"
    24
  when "c1.medium"
    4
  when "c1.xlarge"
    24
  else
    2
  end
end

To learn more about each instance type, see the AWS EC2 Instance Type page.

Installation

This recipe must be installed as delayed_job and not eycloud-recipe-delayed_job.

Simple Installation

To add this recipe to your collection of recipes, or as your first recipe, you can use the helpful ey-recipes command line tool:

cd myapp
gem install engineyard engineyard-recipes
ey-recipes init
ey-recipes clone git://github.com/engineyard/eycloud-recipe-delayed_job.git -n delayed_job
ey recipes upload --apply

If you want to have your recipes run during deploy (rather than the separate ey recipes upload --apply step):

ey-recipes init -d
ey-recipes clone git://github.com/engineyard/eycloud-recipe-delayed_job.git -n delayed_job
git add .; git commit -m "added delayed job recipe"; git push origin master
ey deploy

Manual Installation

Clone/copy this repository into a cookbooks/delayed_job folder (such that you have a cookbooks/delayed_job/recipes/default.rb file).

Then add the following to cookbooks/main/recipes/default.rb:

require_recipe "delayed_job"

Make sure this and any customizations to the recipe are committed to your own fork of this repository.

Then to upload and apply to EY Cloud for a given environment:

ey recipes upload --apply -e target-environment

Restarting your workers

This recipe does NOT restart your workers. The reason for this is that shipping your application and rebuilding your instances (i.e. running chef) are not always done at the same time. It is best to restart your Delayed Job workers when you ship (deploy) your application code. To do this, add a deploy hook to perform the following:

sudo "monit -g dj_<app_name> restart all"

Make sure to replace <app_name> with the name of your application. You likely want to use the after_restart hook for this. See our Deploy Hook documentation for more information on using deploy hooks.