unicorn.rb

app_path = '/var/www/my_app'

worker_processes 1
user 'my_user', 'my_user'
timeout 240
listen '/tmp/unicorn.my_app.sock', backlog: 64

working_directory "#{app_path}/current"
pid "#{app_path}/shared/tmp/pids/unicorn.pid"
stderr_path "#{app_path}/shared/log/unicorn_stderr.log"
stdout_path "#{app_path}/shared/log/unicorn_stdout.log"

preload_app true

before_fork do |server, worker|
  # kills old children after zero downtime deploy
  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