Whenever is a Ruby gem that provides a clear syntax for writing and deploying cron jobs.
$ gem install whenever
Or with Bundler in your Gemfile.
gem 'whenever', :require => false
$ cd /my/rails/app $ wheneverize .
This will create an initial “config/schedule.rb” file you.
Example schedule.rb file
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 every :hour do # Many shortcuts available: :hour, :day, :month, :year, :reboot runner "SomeModel.ladeeda" end every :sunday, :at => '12pm' do # Use any day of the week or :weekend, :weekday runner "Task.do_something_great" end
More examples on the wiki: wiki.github.com/javan/whenever/instructions-and-examples
Define your own job types
Whenever ships with three pre-defined job types: command, runner, and rake. You can define your own with `job_type`.
job_type :awesome, '/usr/local/bin/awesome :task :fun_level' every 2.hours do awesome "party", :fun_level => "extreme" end
Would run `/usr/local/bin/awesome party extreme` every two hours. `:task` is always replaced with the first argument, and any additional `:whatevers` are replaced with the options passed in or by variables that have been defined with `set`.
The default job types that ship with Whenever are defined like so:
job_type :command, ":task :output" job_type :rake, "cd :path && RAILS_ENV=:environment rake :task :output" job_type :runner, "cd :path && script/runner -e :environment ':task' :output"
If a script/rails file is detected (like in a Rails 3 app), runner will be defined to fit:
job_type :runner, "cd :path && script/rails runner -e :environment ':task' :output"
If a `:path` is not set it will default to the directory in which `whenever` was executed. `:environment` will default to 'production'. `:output` will be replaced with your output redirection settings which you can read more about here: github.com/javan/whenever/wiki/Output-redirection-(logging-your-cron-jobs)
All jobs are by default run with `bash -l -c 'command…'`. Among other things, this allows your cron jobs to play nice with RVM by loading the entire environment instead of cron's somewhat limited environment. Read more: blog.scoutapp.com/articles/2010/09/07/rvm-and-cron-in-production
You can change this by setting your own job_template.
set :job_template, "bash -l -c ':job'"
Or set the job_template to nil to have your jobs execute normally.
set :job_template, nil
And you'll see your schedule.rb converted to cron sytax. Note: running `whenever` with no options does not display your current crontab file, it simply shows you the output of converting your schedule.rb file.
Use the built-in Capistrano recipe for easy crontab updates with deploys.
In your “config/deploy.rb” file:
Take a look at the recipe for options you can set. github.com/javan/whenever/blob/master/lib/whenever/capistrano.rb For example, if you're using bundler do this:
set :whenever_command, "bundle exec whenever" require "whenever/capistrano"
The `whenever` command
$ cd /my/rails/app $ whenever
This will simply show you your schedule.rb file converted to cron syntax. It does not read or write your crontab file. Run `whenever –help` for a complete list of options.
Whenever was created for use at Inkling (inklingmarkets.com) where I work. Their take on it: blog.inklingmarkets.com/2009/02/whenever-easy-way-to-do-cron-jobs-from.html
While building Whenever, I learned a lot by digging through the source code of Capistrano - github.com/jamis/capistrano
Discussion / Feedback / Issues / Bugs
For general discussion and questions, please use the google group: groups.google.com/group/whenever-gem
If you've found a genuine bug or issue, please use the Issues section on github: github.com/javan/whenever/issues
Ryan Bates created a great Railscast about Whenever: railscasts.com/episodes/164-cron-in-ruby It's a little bit dated now, but remains a good introduction.
Copyright © 2009+ Javan Makhmali
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