How to use Sidekiq with Padrino on Heroku. This config enables you to run sidekiq inside your "web" dyno (See https://coderwall.com/p/fprnhg for details)

boot.rb

# config/boot.rb

# ...
# Load our dependencies
require 'rubygems' unless defined?(Gem)
require 'bundler/setup'

Bundler.require(:default, PADRINO_ENV)

Padrino.before_load do
  # Load worker definitions
  require File.join(PADRINO_ROOT, 'config', 'workers.rb')
end

# ...

Padrino.after_load do
  # Sidekiq should log to our main log file.
  Sidekiq.logger = Padrino.logger
  # Make sure that all mailers are loaded. Without this I was having problems delivering emails from workers.
  Padrino.require_dependencies("#{Padrino.root}/app/mailers/*.rb")
end

# ...

config.ru

#!/usr/bin/env rackup
# encoding: utf-8

require File.expand_path("../config/boot.rb", __FILE__)

require 'sidekiq/web'
map('/sidekiq') { run Sidekiq::Web }

run Padrino.application

Gemfile

# ...
gem 'sidekiq'
gem 'slim'

gem 'unicorn'
# ...

hard_worker.rb

# workers/hard_worker.rb

class HardWorker
  include Sidekiq::Worker

  def perform(name, count)
    MyApp::App.deliver(:mailer_name, :email_name, name, count)
  end
end

Procfile

web: bundle exec unicorn -p $PORT -c ./config/unicorn.rb

sidekiq.yml

# See http://manuel.manuelles.nl/blog/2012/11/13/sidekiq-on-heroku-with-redistogo-nano/
:concurrency: 2

test.rb

# app/controllers/test.rb

YourApp.controller do
  get '/test' do
    HardWorker.perform_async('bob', 5)
  end
end

unicorn.rb

require 'sidekiq'

worker_processes 3

before_fork do |server, worker|
  # Spawn Sidekiq worker inside the current process.
  @worker_pid = spawn('bundle exec sidekiq -C ./config/sidekiq.yml -r ./config/boot.rb')
  t = Thread.new {
    Process.wait(@worker_pid)
    puts "Worker died. Bouncing unicorn."
    Process.kill 'QUIT', Process.pid
  }
  # Just in case
  t.abort_on_exception = true
end

after_fork do |server, worker|
  Sidekiq.configure_client do |config|
    config.redis = { :size => 1 } # Limit the client size, see http://manuel.manuelles.nl/blog/2012/11/13/sidekiq-on-heroku-with-redistogo-nano/
  end
  Sidekiq.configure_server do |config|
    config.redis = { :size => 2 } # Limit the server size, see http://manuel.manuelles.nl/blog/2012/11/13/sidekiq-on-heroku-with-redistogo-nano/
  end
end

workers.rb

# config/workers.rb

Dir[File.expand_path('../../workers/*.rb', __FILE__)].each{|file|require file}