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Monitor a Rake task with God

In order to monitor a Rake task using God your Rake file must write a file with its process ID (PID) to a path determined by God. This way God can check whether the Rake process is still alive.

Here is how to do this: In your God config, call the Rake task with an environment variable PIDFILE. This variable should equal the PID file path desired by God:

God.watch do |w| w.dir = "#{rails_root}" w.name = "my_task" w.interval = 10.seconds w.pid_file = "#{rails_root}/tmp/pids/#{w.name}.pid" w.env = {"RAILS_ENV"=>rails_env, 'PIDFILE' => w.pid_file} w.start = "bundle exec rake my_task &" ... end

Your Rake task should write its process ID to that PID file:

task :my_task => :environment do File.open(ENV['PIDFILE'], 'w') { |f| f << Process.pid } if ENV['PIDFILE'] Model.perform_task! end

Some advice

Don't let Ruby scripts run forever. You will run into many issues. Instead let your script terminate after 30 minutes or X iterations and trust on God restarting the task.

Author of this card:

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Henning Koch
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We are makandra and do test-driven, agile Ruby on Rails software development.
Posted by Henning Koch to makandropedia