Resque + New Relic

jobs.rb

require 'lib/scaler'

class RecreateFullZip
        @queue = :full_zip
        def self.perform
                zip = CvFile.get_all_as_zip
                AWS::S3::S3Object.store("all.zip", zip, 'datatjejcv')
        end

        extend HerokuResqueAutoScale
end

class AsyncMail
        @queue = :mail
        def self.perform(from, to, subject, body)
                Pony.mail(:from => from, :to => to, :subject => subject, :body => body)
        end

        extend HerokuResqueAutoScale
end

Rakefile

task :environment do
  DataMapper.setup(:default, ENV['DATABASE_URL'])
  AWS::S3::Base.establish_connection!(
                        :access_key_id     => ENV['AMAZON_ACCESS_KEY_ID'],
                        :secret_access_key => ENV['AMAZON_SECRET_ACCESS_KEY'])
  uri = URI.parse(ENV["REDISTOGO_URL"])
  Resque.redis = Redis.new(:host => uri.host, :port => uri.port, :password => uri.password)
  Pony.options = {
    :via => :smtp,
    :via_options => {
      :address        => "smtp.sendgrid.net",
      :port           => "25",
      :authentication => :plain,
      :user_name      => ENV['SENDGRID_USERNAME'],
      :password       => ENV['SENDGRID_PASSWORD'],
      :domain         => ENV['SENDGRID_DOMAIN'] }}
end

require 'resque/tasks'
require 'lib/jobs'
require 'rpm_contrib' if ENV['RACK_ENV'] == 'production'

task 'resque:setup' => :environment do
        ENV['QUEUE'] = '*'
end

task 'jobs:work' => 'resque:work'

scaler.rb

require 'heroku'

module HerokuResqueAutoScale
  module Scaler
    class << self
      @@heroku = Heroku::Client.new(ENV['HEROKU_USER'], ENV['HEROKU_PASS'])

      def workers
        @@heroku.info(ENV['HEROKU_APP'])[:workers].to_i
      end

      def workers=(qty)
        @@heroku.set_workers(ENV['HEROKU_APP'], qty)
      end

      def job_count
        Resque.info[:pending].to_i
      end
    end
  end

  def after_perform_scale_down(*args)
                #NewRelic::Agent.shutdown
    # Nothing fancy, just shut everything down if we have no jobs
    Scaler.workers = 0 if Scaler.job_count.zero?
  end

  def after_enqueue_scale_up(*args)
                if Scaler.workers < 1
                        #NewRelic::Agent.manual_start
                        Scaler.workers = 1
                end
        end
end