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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.

Once an application no longer requires constant development, it needs periodic maintenance for stable and secure operation. makandra offers monthly maintenance contracts that let you focus on your business while we make sure the lights stay on.

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.
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Posted by Henning Koch to makandropedia