Cronjobber¶ ↑

Allows to define cronjobs programmatically.

In your gemfile

gem 'cronjobber', :git => 'git://github.com/giniedp/cronjobber.git'

Run

bundle install

Cronjobber expects that your Database has a table named ‘cronjobs’. Just use the following migration snippet to create the required fields. No, there is no generator for this… don’t ask.

create_table(:cronjobs) do |t|
  t.string :name
  t.datetime :run_at
  t.datetime :locked_at
  t.string :locking_key
  t.integer :duration
  t.text :last_error
  t.integer :total_runs
  t.integer :total_failures
end

In your models directory create one file for each task that you want to perform. I prefer to collect them in an extra directory.

# app/models/cronjobs/my_task.rb
class Cronjob::MyTask < Cronjobber::Task
  # initialize the task
  run_task :every => 5.minutes

  def run
    # task implementation goes here
  end
end

every

The time between executions. Default is 0.minutes.

at

An array with time of day strings when the task should be executed e.g. [“12:00”, “20:00”]. Default is []

in_background

Tells the plugin to run this task in background or not. Default is false. Cronjobber uses delayed_job to delay the execution.

method

The method to use to run the task. Default is :run

Keep in mind that the exact execution time of a task always depends on how often the Cronjobber is triggered

run_task

Will use the default settings. The cronjob will be executed every time the Cronjobber is triggered

run_task :every => 5.minutes

Will execute the task only if 5 minutes are left since the last execution.

run_task :at => %w(12:00 15:00 20:00)

Will execute the task once between the given times.

run_task :every => 30.minutes, :at => "12:00"

Will execute the task every 30 minutes starting at 12:00.

run_task :every => 30.minutes, :at => %w(12:00 15:00 20:00)

Same as above. Only the first value of the at array is respected.

Inside any Controller use the method execute_cronjob_tasks to trigger the Cronjobber. For example in your application controller:

class ApplicationController < ActionController::Base
  def cronjobs
    tasks, log = execute_cronjob_tasks %w(cronjobs/my_task)
    render :text => log.join("\n")
  end
end

The first returning value is an array of all tasks. The second is an array of status messages for each task. In order to activate a cronjob task, you have to list it in the first argument of the execute_cronjob_tasks method, or in the config.cronjobber.tasks configuration setting in your config/application.rb.

Now you have to make sure that the action is visited periodically. For example with a Unix crontab entry:

*/1 * * * * curl http://your-app.com/cronjobs # visits http://your-app.com/cronjobs every minute