unicorn.conf.rb

listen "/srv/hubbub/shared/customer_workers.sock", :tcp_nodelay => true

working_directory '/srv/hubbub/current'

timeout 60
preload_app true
worker_processes 4

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

  # Gracefully handle restarts. If the PID file has changed, then a new version
  # has been deployed with a new master. Start gracefully shutting down the old
  # Unicorn workers as they finish requests, and then shut down the master once
  # there are no workers left.
  old_pid = '/srv/hubbub/shared/pids/customer_workers.pid.oldbin'
  if server.pid != old_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
      # someone else did our job for us
    end
  end
  sleep 0.5
end

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

pid '/srv/hubbub/shared/pids/customer_workers.pid'

# http://www.rubyenterpriseedition.com/faq.html#adapt_apps_for_cow
if GC.respond_to?(:copy_on_write_friendly=)
  GC.copy_on_write_friendly = true
end

# https://newrelic.com/docs/ruby/ruby-gc-instrumentation
if GC.respond_to?(:enable_stats)
  GC.enable_stats
end
if defined?(GC::Profiler) and GC::Profiler.respond_to?(:enable)
  GC::Profiler.enable
end

upstart.conf

description "Customer Site Unicorns"

start on filesystem or runlevel [2345]
stop on runlevel [!2345]

respawn
respawn limit 10 5

setuid hubbub
setgid hubbub

chdir /srv/hubbub/current

script
  while true; do
    if [ ! -f /srv/hubbub/shared/pids/customer_workers.pid ]; then
      # Run the unicorn master process (this won't return until it exits).
      bundle1.8 exec /srv/hubbub/shared/vendor_bundle/ruby/1.8/bin/unicorn -c /etc/unicorn/customer_workers.conf.rb
    else
      # Someone restarted the master; wait for the new master to exit.
      PID=`cat /srv/hubbub/shared/pids/customer_workers.pid`
      while [ -d /proc/$PID ]; do
        sleep 40
      done

      # If we get here, the master has exited, either because someone restarted
      # it again (in which case there's already a new master running), or
      # it died for real (in which case we'll need to start a new process).
      # The sleep above is a tradeoff between polling load and mimizing the
      # restart delay when the master dies for real (which should hopefully be
      # rare).
    fi
  done
end script