A cron job for rails: best practices?

Question

What's the best way to run scheduled tasks in a Rails environment? Script/runner? Rake?

Answer 1

I have recently created some cron jobs for the projects I have been working on.

I found that the gem Clockwork very useful.

require 'clockwork'

module Clockwork
  every(10.seconds, 'frequent.job')
end

You can even schedule your background job using this gem. For documentation and further help refer https://github.com/Rykian/clockwork

Answer 2

I'm not really sure, I guess it depends on the task: how often to run, how much complicated and how much direct communication with the rails project is needed etc. I guess if there was just "One Best Way" to do something, there wouldn't be so many different ways to do it.

At my last job in a Rails project, we needed to make a batch invitation mailer (survey invitations, not spamming) which should send the planned mails whenever the server had time. I think we were going to use daemon tools to run the rake tasks I had created.

Unfortunately, our company had some money problems and was "bought" by the main rival so the project was never completed, so I don't know what we would eventually have used.

Answer 3

script/runner and rake tasks are perfectly fine to run as cron jobs.

Here's one very important thing you must remember when running cron jobs. They probably won't be called from the root directory of your app. This means all your requires for files (as opposed to libraries) should be done with the explicit path: e.g. File.dirname(__FILE__) + "/other_file". This also means you have to know how to explicitly call them from another directory :-)

Check if your code supports being run from another directory with

# from ~
/path/to/ruby /path/to/app/script/runner -e development "MyClass.class_method"
/path/to/ruby /path/to/rake -f /path/to/app/Rakefile rake:task RAILS_ENV=development

Also, cron jobs probably don't run as you, so don't depend on any shortcut you put in .bashrc. But that's just a standard cron tip ;-)

Answer 4

I use backgroundrb.

http://backgroundrb.rubyforge.org/

I use it to run scheduled tasks as well as tasks that take too long for the normal client/server relationship.

Answer 5

I've used the extremely popular Whenever on projects that rely heavily on scheduled tasks, and it's great. It gives you a nice DSL to define your scheduled tasks instead of having to deal with crontab format. From the README:

Whenever is a Ruby gem that provides a clear syntax for writing and deploying cron jobs.

Example from the README:

every 3.hours do
  runner "MyModel.some_process"       
  rake "my:rake:task"                 
  command "/usr/bin/my_great_command"
end

every 1.day, :at => '4:30 am' do 
  runner "MyModel.task_to_run_at_four_thirty_in_the_morning"
end

Answer 6

That is interesting no one mentioned the Sidetiq. It is nice addition if you already using Sidekiq.

Sidetiq provides a simple API for defining recurring workers for Sidekiq.

Job will look like this:

class MyWorker
  include Sidekiq::Worker
  include Sidetiq::Schedulable

  recurrence { hourly.minute_of_hour(15, 45) }

  def perform
    # do stuff ...
  end
end