Upstart + Bluepill + Unicorn with hot restart

project-web-reload.conf

# /etc/init/project-web-reload.conf

pre-start script
  initctl restart project-web
  sleep 15
end script

exec /usr/local/rvm/bin/default_bluepill restart

project-web.conf

# /etc/init/project-web.conf

respawn

expect daemon

pre-start script
  bash <<'EOS'
    source /usr/local/rvm/scripts/rvm
    ruby -e 'begin; Gem::Specification.find_by_name("bluepill"); rescue Gem::LoadError; exit 1; end; exit 0'
    retval=$?
    if [ "$retval" -ne 0 ]; then
      gem install bluepill --no-rdoc --no-ri
      rvm wrapper default default bluepill
    fi
  EOS
  mkdir -p /var/www/project
  mkdir -p /var/log/project
  mkdir -p /var/run/project
  chown -R www /var/www/project
  chown -R www /var/log/project
  chown -R www /var/run/project
end script

exec /usr/local/rvm/bin/default_bluepill load /var/www/project/config/project-web.pill

project-web.pill.rb

# /var/www/project/config/project-web.pill

Bluepill.application('project-web', log_file: '/var/log/project/bluepill.log') do |app|
  app.working_dir = '/var/www/project'
  app.uid = 'www'
  app.gid = 'rvm'

  app.process('unicorn') do |process|
    process.start_command    = 'bundle exec unicorn -E production -c /var/www/project/config/unicorn.rb -D'
    process.stop_command     = 'start-stop-daemon --signal QUIT --stop --pidfile /var/run/project/web.pid'
    process.restart_command  = 'start-stop-daemon --signal USR2 --stop --pidfile /var/run/project/web.pid'
    process.pid_file         = '/var/run/project/web.pid'
    process.start_grace_time = 30.seconds
    process.stop_grace_time  = 30.seconds
  end
end

unicorn.rb

# /var/www/project/config/unicorn.rb

worker_processes 4
working_directory '/var/www/project'
listen '/tmp/project.web.sock', backlog: 2048
timeout 60
pid '/var/run/project/web.pid'
stderr_path '/var/log/project/unicorn.stderr.log'
stdout_path '/var/log/project/unicorn.stdout.log'
preload_app true
GC.respond_to?(:copy_on_write_friendly=) and
  GC.copy_on_write_friendly = true

before_fork do |server, worker|
  defined?(ActiveRecord::Base) and
    ActiveRecord::Base.connection.disconnect!

  old_pid = "#{server.config[:pid]}.oldbin"
  if old_pid != server.pid
    begin
      sig = (worker.nr + 1) >= server.worker_processes ? :QUIT : :TTOU
      Process.kill(sig, File.read(old_pid).to_i)
    rescue Errno::ENOENT, Errno::ESRCH
    end
  end

  sleep 1
end

after_fork do |server, worker|
  defined?(ActiveRecord::Base) and
    ActiveRecord::Base.establish_connection

  defined?(Rails) and Rails.cache.respond_to?(:reconnect) and
    Rails.cache.reconnect
end