Rake task to restart one heroku web instance every 10 minutes

heroku.rake

# Add `gem 'heroku-api', :git => 'https://github.com/heroku/heroku.rb.git'` to your Gemfile
# Set the APP_NAME environment variable to the name of the Heroku app you wish to control.
# Set the HEROKU_API_KEY environment variable to the API key found on the Heroku 'My Account' page.

# You can now create a scheduler instance that runs `bundle exec rake heroku:web:restart` to automate
# restarting workers. The task will select a different web instance every 10 minutes, based on the number of instances that are running.

namespace :heroku
  namespace :web do
    task :restart do
      heroku = Heroku::API.new
      response = heroku.get_ps(ENV['APP_NAME']) 
      web_processes = response.body.map {|item| item['process'] }.select { |item| item =~ /web/ }

      which_process_index = HerokuHelpers.which_web_process_to_restart?(
        web_processes.length,
        DateTime.now)
      process = web_processes[which_process_index]

      puts "Restarting #{process}"
      heroku.post_ps_restart(ENV['APP_NAME'], 'ps' => process) rescue nil
    end
  end
end

heroku_helpers.rb

require 'time'

module HerokuHelpers
  def self.which_web_process_to_restart?(workers, time)
    ((time.hour * 60 + time.min) / 10) % workers
  end
end

heroku_helpers_spec.rb

require 'spec_helper_no_rails'
require 'heroku_helpers'

describe HerokuHelpers do
  context '.which_web_process_to_restart?' do
    context 'with 4 workers' do
      start = Time.parse('00:00:00')
      144.times do |index|
        time = start + 60 * 10 * index
        expected_result = index % 4

        it "should return #{expected_result} at #{time.strftime('%T')}" do
          HerokuHelpers.which_web_process_to_restart?(4, time).should == expected_result
        end

        it "should return #{expected_result} at #{(time + 2).strftime('%T')}" do
          HerokuHelpers.which_web_process_to_restart?(4, time + 2).should == expected_result
        end
      end
    end

    context 'with 3 workers' do
      start = Time.parse('00:00:00')
      144.times do |index|
        time = start + 60 * 10 * index
        expected_result = index % 3

        it "should return #{expected_result} at #{time.strftime('%T')}" do
          HerokuHelpers.which_web_process_to_restart?(3, time).should == expected_result
        end

        it "should return #{expected_result} at #{(time + 2).strftime('%T')}" do
          HerokuHelpers.which_web_process_to_restart?(3, time + 2).should == expected_result
        end
      end
    end
  end
end

thanks for sharing