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This add-on is operated by Crazy Ant Labs

Run scheduled tasks on your Heroku Apps.

Cron To Go

Last updated 19 March 2019

Cron To Go is an add-on for running scheduled jobs on one-off dynos using cron expressions.

Cron To Go combines the simplicity of using cron to schedule jobs with the scale and elasticity of the cloud. Instead of running always-on processes, use Cron To Go to start one-off dynos only when you need them.

Provisioning the add-on

Cron To Go can be attached to a Heroku application via the CLI:

$ heroku addons:create crontogo
-----> Adding crontogo to sharp-mountain-4005... done, v18 (free)

After you provision Cron To Go, you can use its dashboard to define and schedule jobs.

Dashboard

The Cron To Go dashboard allows you to create jobs, alter job definitions, and delete jobs. You can also pause or resume jobs.

You can access the dashboard via the CLI:

$ heroku addons:open crontogo
Opening crontogo for sharp-mountain-4005

or by visiting the Heroku Dashboard and selecting the application in question. Select Cron To Go from the Add-ons menu.

Defining Jobs

A job in Cron To Go consists of the following:

• An optional nickname (for example, Daily ETL).
• The job’s frequency, in cron expression format. The smallest interval you can specify is every minute.
• The command to execute.
• The size of one-off dyno to execute the command in. Read more about available one-off dyno types.

When triggered, these jobs run in one-off dynos and show up in your logs as a dyno named crontogo.[job_id].

Using with Rails

Cron To Go can run any command that can be run in your application. In Rails, the convention is to set up rake tasks. To create tasks in Rails, copy the code below to lib/tasks/scheduler.rake and customize it to fit your needs:

desc "This task is called by the Cron To Go"
task :eat_breakfast => :environment do
  puts "Eating breakfast..."
  Kitchen.eat
  puts "done."
end

task :excercise => :environment do
  puts "Starting workout..."
  Gym.workout
  puts "done."
end

After writing a task and deploying it to Heroku, you can test it using heroku run:

$ heroku run rake eat_breakfast

After testing on Heroku, you can add a job to Cron To Go that specifies rake eat_breakfast as the command to run.

Using with Node.js

Cron To Go can run any command that can be run in your application. For Node.js, you can simply add a file to your app called schedules.js and execute it:

module.exports.eat_breakfast = function()
{
        console.log('Eating breakfast...');
        Kitchen.eat();
        console.log('done.');
}

require('make-runnable');

After writing your task and deploying it to Heroku, test it using heroku run:

$ heroku run node schedules.js eat_breakfast

After testing on Heroku, you can add a job to Cron To Go that specifies node schedules.js eat_breakfast as the command to run.

Monitoring and logging

One-off dynos that execute as part of Cron To Go output their logs with process crontogo.[job_id].

Migrating between plans

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

$ heroku addons:upgrade crontogo:starter
-----> Upgrading crontogo:newplan to sharp-mountain-4005... done, v18 ($49/mo)
       Your plan has been updated to: crontogo:starter

Removing the add-on

You can remove Cron To Go via the CLI:

$ heroku addons:destroy crontogo
-----> Removing crontogo from sharp-mountain-4005... done, v20 (free)

Support

All Cron To Go support and runtime issues should be submitted via one of the Heroku Support channels. Any non-support related issues or product feedback is welcome at support@crazyantlabs.com.