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Thor Script for Managing a Unicorn-driven App

Today I deployed a mini sinatra app on one of our test servers to manage some internal QA. I’ve put out quite a few apps backed by Unicorn in QA recently and finally wrote a little script to handle stopping, starting, and reloading of the unicorn processes. Nothing super special here, just thought I’d share a useful script. Drop the following code into your application’s tasks directory, or place it on the app root and call it Thorfile.

tasks/unicorn.thor (or Thorfile)

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# put me in /path/to/app/tasks/unicorn.thor

require 'thor'



class UnicornRunner < Thor

  include Thor::Group



  namespace :unicorn



  UNICORN_CONFIG = "/path/to/app/config/unicorn.rb"

  RACKUP_FILE = "/path/to/app/config.ru"

  PID_FILE = "/path/to/app/tmp/application.pid"



  desc 'start', 'Start the application'

  def start

    say 'Starting the application...', :yellow

    `bundle exec unicorn -c #{UNICORN_CONFIG} -E production -D #{RACKUP_FILE}`

    say 'Done', :green

  end



  desc 'stop', 'Stop the application'

  def stop

    say 'Stopping the application...', :yellow

    `kill -QUIT $(cat #{PID_FILE})`

    say 'Done', :green

  end



  desc 'reload', 'Reload the application'

  def reload

    say 'Reloading the application...', :yellow

    `kill -USR2 $(cat #{PID_FILE})`

    say 'done', :green

  end

end

Usage

From your application root directory, run any of the three commands. Keep in mind you’ll need a unicorn config file that actually dictates how Unicorn should behave (like number of workers, where your logs go, etc). You’ll also need a Rackup file (config.ru) which tells unicorn how to run your app.

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$ thor -T

# thor unicorn:start    Start the application

# thor unicorn:stop     Stop the application

# thor unicorn:reload   Reload the application



$ thor unicorn:start    # starts the unicorn master

$ thor unicorn:stop     # sends the QUIT signal to master (graceful shutdown)

$ thor unicorn:reload   # sends the USR2 signal to master (graceful reload of child workers)

Plop this puppy behind nginx and you’re golden. Thor has a lot more things you could do with this (like overriding which config file to use) by providing method-level options, but this is a great starting point for most people. Leave a comment if you have any improvements or other ways you handle this.

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