My capistrano + rainbows configure

deploy.rb

# Check if remote file exists
def remote_file_exists?(full_path)
  'true' ==  capture("if [ -e #{full_path} ]; then echo 'true'; fi").strip
end

# Check if process is running
def remote_process_exists?(pid_file)
  capture("ps -p $(cat #{pid_file}) ; true").strip.split("\n").size == 2
end

set(:rainbows_pid) { "#{current_path}/tmp/pids/rainbows.pid" }
set(:rainbows_bin) { "BUNDLE_GEMFILE=#{current_path}/Gemfile bundle exec rainbows" }
set(:rainbows_config) { "#{current_path}/config/rainbows.rb" }

namespace :rainbows do
  task :start, roles: :app, except: {no_release: true} do
    if remote_file_exists?(rainbows_pid)
      if remote_process_exists?(rainbows_pid)
        logger.important("Rainbows! is already running!", "rainbows")
        next
      else
        run "rm #{rainbows_pid}"
      end
    end

    if remote_file_exists?(rainbows_config)
      logger.important("Starting...", "rainbows")
      run "cd #{current_path}; #{rainbows_bin} -c #{rainbows_config} -E #{rails_env} -D"
    else
      logger.important("Config file was not found at \"#{rainbows_config}\"", "rainbows")
    end
  end

  task :stop, roles: :app, except: {no_release: true} do
    if remote_file_exists?(rainbows_pid)
      if remote_process_exists?(rainbows_pid)
        logger.important("Stopping...", "rainbows")
        run "#{try_sudo} kill -s QUIT `cat #{rainbows_pid}`"
      else
        run "rm #{rainbows_pid}"
        logger.important("Rainbows! is not running.", "rainbows")
      end
    else
      logger.important("No PIDs found. Check if rainbows is running.", "rainbows")
    end
  end

  task :restart, roles: :app, except: {no_release: true} do
    if remote_file_exists?(rainbows_pid)
      if remote_process_exists?(rainbows_pid)
        logger.important("Stopping...", "rainbows")
        run "#{try_sudo} kill -s USR2 `cat #{rainbows_pid}`"
      else
        run "rm #{rainbows_pid}"
        logger.important("Rainbows! is not running.", "rainbows")
        start
      end
    else
      logger.important("No PIDs found.", "rainbows")
      start
    end
  end
end

rainbows.rb

# Set your full path to application.
app_path = File.expand_path(File.join(File.dirname(__FILE__), '..'))

# Set rainbows options
worker_processes 4
preload_app true
timeout 180
listen 4500

# Spawn rainbows master worker for user apps (group: apps)
# user 'apps', 'apps'

# Fill path to your app
working_directory app_path

# Should be 'production' by default, otherwise use other env
rails_env = ENV['RAILS_ENV'] || 'production'

# Log everything to one file
stderr_path 'log/rainbows.log'
stdout_path 'log/rainbows.log'

# Set master PID location
pid "#{app_path}/tmp/pids/rainbows.pid"

before_fork do |server, worker|
  ActiveRecord::Base.connection.disconnect!

  old_pid = "#{server.config[:pid]}.oldbin"
  if File.exists?(old_pid) && server.pid != old_pid
    begin
      Process.kill("QUIT", File.read(old_pid).to_i)
    rescue Errno::ENOENT, Errno::ESRCH
      # someone else did our job for us
    end
  end
end

after_fork do |server, worker|
  ActiveRecord::Base.establish_connection
end

Rainbows! do
  use :EventMachine
  worker_connections 1024
end