Posted almost 4 years ago. Visible to the public.

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.

Growing Rails Applications in Practice
Check out our new e-book:
Learn to structure large Ruby on Rails codebases with the tools you already know and love.

Author of this card:

Avatar
Henning Koch
About this deck:
We are makandra and do test-driven, agile Ruby on Rails software development.
License for source code

License for source code

All source code included in the card Monitor a Rake task with God is licensed under the license stated below. This includes both code snippets embedded in the card text and code that is included as a file attachment. Excepted from this license are code snippets that are explicitely marked as citations from another source.

The MIT License (MIT)

Copyright (c) 2011-2012 makandra GmbH

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to permit
persons to whom the Software is furnished to do so, subject to the
following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
USE OR OTHER DEALINGS IN THE SOFTWARE.
Posted by Henning Koch to makandropedia