Komodo is a simple wrapper for Delayed::Job that helps you autoscale workers when deployed on Heroku. It came about for an upcoming project of ours, which only required the occasional background worker.

Please note: This is still very early days for Komodo, there's very little (read: zero) test coverage - and we've yet to even put it into production.

Setup delayed_job as per the instructions on Heroku.

Add Komodo to your Gemfile:

gem "komodo"

Add a /config/komodo.yml file to your Rails 3 project directory and add the following:

defaults: &defaults
  max_workers: 1
  application_name: my_heroku_application
  username: email@myherokuapplication.com
  password: sekrit

development:
  <<: *defaults

test:
  <<: *defaults

production:
  <<: *defaults

Komodo is set up to (try and) be as abstract as possible. Queuing a function works similar to delayed_job, just call:

Komodo.queue object, :function, [arg1, arg2]

For example:

Komodo.queue @image, :resize, {:width => 900, :height => 450}
# -- or --
Komodo.queue UserMailer.send_registration_notification(@user), :deliver

Komodo will automatically add and remove workers as the queue fills up and empties, respectively.

As stated above, this is really a pre-alpha of Komodo, as such the scaling is very basic; Komodo just ramps straight up to the user-configured maximum.