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Highly available and scalable task queue / worker service.


Last Updated: 07 May 2015

Table of Contents

IronWorker is a massively scalable task queue/job queue that makes it easy for you offload front end tasks, run background jobs, and process many tasks at once – all in the cloud and with no servers to set up and manage. It can also function as a cron-in-the-cloud service, running tasks on a schedule you define.

IronWorker has partnered with Heroku to make using both services together even easier.

Get started

It’s quick and easy to get IronWorker set up and running on Heroku using your language of choice. Note that Ruby IronWorker currently requires Ruby 1.9 or later. Please check the Heroku documentation to find out whether your stack is supported and how to select a supported stack.

Once you have a stack selected, you need to install the IronWorker addon for Heroku. You can do this with a quick command:

$ heroku addons:create iron_worker
-----> Adding iron_worker to strong-mountain-405... done, v29 (free)

This will add the developer level addon for IronWorker, which will let you test the addon and play around a bit. There are other levels of the addon, as well.

Install the iron_worker_ng gem:

$ gem install iron_worker_ng


Now that you’ve added the addon, you need to retrieve your token and project ID. The token functions as a password, so please keep it secure! Each app has a different project ID. You can get the token and project ID by running the following command:

$ heroku config | grep IRON
IRON_WORKER_TOKEN      => aslkdjflaksuilaks

You can also get your token and project ID from the HUD. To get to the HUD, go to your apps panel for Heroku, choose your app, expand the addons drop-down, and click on IronWorker. This will bring you to the IronWorker HUD, where you can see your project ID and token listed.

IronWorker addon

Add those values to a file called iron.json in your app root directory and add iron.json to your .gitignore file.

  "project_id": "123456789",
  "token": "aslkdjflaksuilaks"

Create a worker

First things first, let’s create a worker. Save the following code into a file called hello_worker.rb:

# Worker code can be anything you want.
puts "Starting HelloWorker at #{}"
puts "Payload: #{params}"
puts "Simulating hard work for 5 seconds..."
5.times do |i|
  puts "Sleep #{i}..."
  sleep 1
puts "HelloWorker completed at #{}"

Now create a file called hello.worker that defines your worker’s dependencies:

# define the runtime language, this can be ruby, java, node, php, go, etc.
runtime "ruby"
# exec is the file that will be executed:
exec "hello_worker.rb"

Now upload it:

iron_worker upload hello

Now you’re work is ready to be used. You can quickly test it by running:

iron_worker queue hello -p "{\"hello\": \"world\"}"

Now you can view the log for the worker with:

iron_worker log -t 4fcfc8d11bab475a360abd92

Or look at the log in HUD.

Now it’s time to put your worker to work!

Queue up tasks for your worker from your application

Now that we know the worker runs and uploads from your machine, we want to run it from within your application within Heroku. Heroku automatically adds the token and project ID to your production environment variables. You need to take care of your development environment yourself, however. Simply add the following to your config/environments/development.rb:


If you’re using bundler, add the following to your Gemfile:

gem 'iron_worker_ng'

Assuming you’re using Rails, let’s add some code to one of your controllers. For instance, let’s say you have a controller called WelcomeController:

class WelcomeController < ApplicationController
  def index
    iron_worker =
    iron_worker.tasks.create("hello", "foo"=>"bar")

Deploy the app to Heroku, and load up to queue up the task.

Next steps

This is just the tip of the iceberg. IronWorker has a robust API that allows for a lot more interaction with your workers. You may want to try:

You can also check out some example workers:

  • TweetWorker, an app that pulls tweets and displays them. It uses IronWorker, IronMQ, and Sinatra, all while being hosted on Heroku.
  • We also have a full repository of IronWorker examples for Rails on Github.


When trying to troubleshoot a worker, the best first step is to try and run the worker locally. If the worker runs locally, it should run on the cloud. You can also access your worker logs through the HUD. These logs will show you any errors thrown or debug messages you log while the worker is running.

The most common source of worker errors is a mismatch between your local environment and the cloud’s environment. Double-check your Gemfile and your Ruby version – workers run under Ruby >1.9. Also, make sure your Gemfile.lock has been updated. Run bundle install to make sure.

Issues should get logged with Heroku Support. You’re also welcome to stop by the support chat room and chat with Iron’s staff about issues. You can also find more resources and documentation on the Dev Center.