God configs for starting Resque and Unicorn

all.god

PID_DIR       = '/srv/myapp/shared/pids'
RAILS_ENV     = ENV['RAILS_ENV'] = 'production'
RAILS_ROOT    = ENV['RAILS_ROOT'] = '/srv/myapp/current'
BIN_PATH      = "/home/rails/.rvm/gems/ree-1.8.7-2010.02/bin"

God.log_file  = "#{RAILS_ROOT}/log/god.log"
God.log_level = :info

%w(unicorn resque).each do |config|
  God.load "#{RAILS_ROOT}/config/god/#{config}.god"
end

resque.god

num_workers = (RAILS_ENV == 'production') ? 4 : 2
 
num_workers.times do |num|
  God.watch do |w|
    w.name = "resque-#{num}"
    w.group = 'resque'
    w.interval = 30.seconds
    w.env = {"QUEUE"=>"*", "RAILS_ENV"=>RAILS_ENV}

    # resque:work has a dependency on environment in my Rakefile, so no need to call it first
    w.start = "#{BIN_PATH}/rake -f #{RAILS_ROOT}/Rakefile resque:work"
 
    w.uid = 'rails' # user id
    w.gid = 'rails' # group id
 
    # restart if memory gets too high
    w.transition(:up, :restart) do |on|
      on.condition(:memory_usage) do |c|
        c.above = 350.megabytes
        c.times = 2
      end
    end
 
    # determine the state on startup
    w.transition(:init, { true => :up, false => :start }) do |on|
      on.condition(:process_running) do |c|
        c.running = true
      end
    end
 
    # determine when process has finished starting
    w.transition([:start, :restart], :up) do |on|
      on.condition(:process_running) do |c|
        c.running = true
        c.interval = 5.seconds
      end
 
      # failsafe
      on.condition(:tries) do |c|
        c.times = 5
        c.transition = :start
        c.interval = 5.seconds
      end
    end
 
    # start if process is not running
    w.transition(:up, :start) do |on|
      on.condition(:process_running) do |c|
        c.running = false
      end
    end
  end
end

unicorn.god

# http://unicorn.bogomips.org/SIGNALS.html

God.watch do |w|
  w.name = "unicorn"
  w.interval = 30.seconds # default
  
  # unicorn needs to be run from the rails root
  w.start = "cd #{RAILS_ROOT} && #{BIN_PATH}/unicorn_rails -c #{RAILS_ROOT}/config/unicorn.rb -E #{RAILS_ENV} -D"

  # QUIT gracefully shuts down workers
  w.stop = "kill -QUIT `cat #{PID_DIR}/unicorn.pid`"

  # USR2 causes the master to re-create itself and spawn a new worker pool
  w.restart = "kill -USR2 `cat #{PID_DIR}/unicorn.pid`"

  w.start_grace = 10.seconds
  w.restart_grace = 10.seconds
  w.pid_file = "#{PID_DIR}/unicorn.pid"

  w.uid = 'rails'
  w.gid = 'rails'

  w.behavior(:clean_pid_file)

  w.start_if do |start|
    start.condition(:process_running) do |c|
      c.interval = 5.seconds
      c.running = false
    end
  end

  w.restart_if do |restart|
    restart.condition(:memory_usage) do |c|
      c.above = 300.megabytes
      c.times = [3, 5] # 3 out of 5 intervals
    end

    restart.condition(:cpu_usage) do |c|
      c.above = 50.percent
      c.times = 5
    end
  end

  # lifecycle
  w.lifecycle do |on|
    on.condition(:flapping) do |c|
      c.to_state = [:start, :restart]
      c.times = 5
      c.within = 5.minute
      c.transition = :unmonitored
      c.retry_in = 10.minutes
      c.retry_times = 5
      c.retry_within = 2.hours
    end
  end
end