163 lines
5.3 KiB
Markdown
163 lines
5.3 KiB
Markdown
### Introduction
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Whenever is a Ruby gem that provides a clear syntax for writing and deploying cron jobs.
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### Installation
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```sh
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$ gem install whenever
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```
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Or with Bundler in your Gemfile.
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```ruby
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gem 'whenever', :require => false
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```
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### Getting started
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```sh
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$ cd /my/rails/app
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$ wheneverize .
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```
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This will create an initial `config/schedule.rb` file you.
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### Example schedule.rb file
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```ruby
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every 3.hours do
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runner "MyModel.some_process"
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rake "my:rake:task"
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command "/usr/bin/my_great_command"
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end
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every 1.day, :at => '4:30 am' do
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runner "MyModel.task_to_run_at_four_thirty_in_the_morning"
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end
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every :hour do # Many shortcuts available: :hour, :day, :month, :year, :reboot
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runner "SomeModel.ladeeda"
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end
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every :sunday, :at => '12pm' do # Use any day of the week or :weekend, :weekday
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runner "Task.do_something_great"
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end
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every '0 0 27-31 * *' do
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command "echo 'you can use raw cron syntax too'"
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end
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```
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### Define your own job types
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Whenever ships with three pre-defined job types: command, runner, and rake. You can define your own with `job_type`.
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For example:
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```ruby
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job_type :awesome, '/usr/local/bin/awesome :task :fun_level'
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every 2.hours do
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awesome "party", :fun_level => "extreme"
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end
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```
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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`.
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The default job types that ship with Whenever are defined like so:
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```ruby
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job_type :command, ":task :output"
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job_type :rake, "cd :path && RAILS_ENV=:environment rake :task :output"
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job_type :runner, "cd :path && script/runner -e :environment ':task' :output"
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```
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If a `script/rails` file is detected (like in a Rails 3 app), runner will be defined to fit:
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```ruby
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job_type :runner, "cd :path && script/rails runner -e :environment ':task' :output"
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```
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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: <http://github.com/javan/whenever/wiki/Output-redirection-aka-logging-your-cron-jobs>
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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: <http://blog.scoutapp.com/articles/2010/09/07/rvm-and-cron-in-production>
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You can change this by setting your own `:job_template`.
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```ruby
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set :job_template, "bash -l -c ':job'"
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```
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Or set the job_template to nil to have your jobs execute normally.
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```ruby
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set :job_template, nil
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```
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### Capistrano integration
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Use the built-in Capistrano recipe for easy crontab updates with deploys.
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In your "config/deploy.rb" file:
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```ruby
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require "whenever/capistrano"
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```
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Take a look at the recipe for options you can set. <http://github.com/javan/whenever/blob/master/lib/whenever/capistrano.rb>
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For example, if you're using bundler do this:
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```ruby
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set :whenever_command, "bundle exec whenever"
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require "whenever/capistrano"
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```
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If you are using different environments (such as staging, production), then you may want to do this:
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```ruby
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set :whenever_environment, defer { stage }
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require "whenever/capistrano"
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```
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The capistrano variable `:stage` should be the one holding your environment name. This will make the correct `:environment` available in your `schedule.rb`.
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### RVM Integration
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If your production environment uses RVM (Ruby Version Manager) you will run into a gotcha that causes your cron jobs to hang. This is not directly related to Whenever, and can be tricky to debug. Your .rvmrc files must be trusted or else the cron jobs will hang waiting for the file to be trusted. A solution is to disable the prompt by adding this line to your user rvm file in `~/.rvmrc`
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`rvm_trust_rvmrcs_flag=1`
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This tells rvm to trust all rvmrc files, which is documented here: http://wayneeseguin.beginrescueend.com/2010/08/22/ruby-environment-version-manager-rvm-1-0-0/
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### The `whenever` command
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```sh
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$ cd /my/rails/app
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$ whenever
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```
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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.
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### Credit
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Whenever was created for use at Inkling (<http://inklingmarkets.com>). Their take on it: <http://blog.inklingmarkets.com/2009/02/whenever-easy-way-to-do-cron-jobs-from.html>
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Thanks to all the contributors who have made it even better: <http://github.com/javan/whenever/contributors>
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### Discussion / Feedback / Issues / Bugs
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For general discussion and questions, please use the google group: <http://groups.google.com/group/whenever-gem>
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If you've found a genuine bug or issue, please use the Issues section on github: <http://github.com/javan/whenever/issues>
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Ryan Bates created a great Railscast about Whenever: <http://railscasts.com/episodes/164-cron-in-ruby>
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It's a little bit dated now, but remains a good introduction.
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----
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Compatible with Ruby 1.8.7-1.9.2, JRuby, and Rubinius. [](http://travis-ci.org/javan/whenever)
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----
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Copyright © 2011 Javan Makhmali |