merb_mpc.god

# run with:  god -c /path/to/merb_mpc.god
# 
# This script controls the multi-process Merb 1.0 service

# To implement:

  # start program = "/home/deploy/bin/monit_merb_mpc slice start_master /home/deploy/legodata -c2 -n4000"
  # stop program = "/home/deploy/bin/monit_merb_mpc slice stop_master /home/deploy/legodata"
  # 
  # start program = "/home/deploy/bin/monit_merb_mpc slice register_worker /home/deploy/legodata 4000"
  # stop program = "/home/deploy/bin/monit_merb_mpc slice restart_worker /home/deploy/legodata 4000"
  # 
  # start program = "/home/deploy/bin/monit_merb_mpc slice register_worker /home/deploy/legodata 4001"
  # stop program = "/home/deploy/bin/monit_merb_mpc slice restart_worker /home/deploy/legodata 4001"

  #  /usr/local/bin/merb --name slice3_production -d -u deploy -G www-data -a mongrel \
  #  -L /home/deploy/legodata/slice3/current/log/production.log -e production -m /home/deploy/legodata/slice3/current \
  #  -c 2 -P '/home/deploy/legodata/slice3/shared/pids/production-merb.%s.pid' -p 4004
  
  # restart_worker command="$merb -K $worker_id -e $environment -m $app_dir -P '$pid_dir/$real_pid_file'"
  
# ====
#
# Config
#
# ====  

APP_NAME        = "slice3"
APP_ENV         = "production"
APP_ROOT        = File.join("/home/deploy/legodata/", APP_NAME)

APP_USER        = "deploy"
APP_GROUP       = "www-data"
APP_ADAPTER     = "mongrel"
APP_PIDS        = File.join(APP_ROOT, "/shared/pids/")

CLUSTER_NODES   = 2
CLUSTER_PORT    = 4004



# ====
#
# Worker process
#
# ====


def merb_worker(port)
  
  God.watch do |w|
    w.name = "#{APP_NAME}-#{APP_ENV} worker - port #{port}"
    w.interval = 30.seconds # default      
    w.start_grace = 10.seconds
    w.restart_grace = 10.seconds
    w.pid_file = File.join(APP_PIDS, "production-merb.#{port}.pid")
  
    w.start = ""
    w.stop = ""
    
    w.restart = "merb -K #{port} -e #{APP_ENV} -m #{File.join(APP_ROOT, "/current")} \
                -P '#{File.join(APP_PIDS, "production-merb.#{port}.pid")}'"
  
    w.uid = APP_USER
    w.gid = APP_GROUP
    w.group = APP_NAME
  
    w.behavior(:clean_pid_file)
  
    w.restart_if do |restart|
      restart.condition(:memory_usage) do |c|
        c.above = 150.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.retry_in = 10.minutes
        c.retry_times = 5
        c.retry_within = 2.hours
      end
    end
  end
  
end

# ====
#
# Master process
#
# ====

God.watch do |w|
  w.name = "#{APP_NAME}-#{APP_ENV} master"
  w.interval = 30.seconds # default      
  w.start_grace = 10.seconds
  w.restart_grace = 10.seconds
  w.pid_file = File.join(APP_PIDS, "production-merb.main.pid")
  
  w.uid = APP_USER
  w.gid = APP_GROUP
  w.group = APP_NAME
  
  w.start = "merb --name #{APP_NAME}-#{APP_ENV} -d \
            -u #{APP_USER} -G #{APP_GROUP} -a #{APP_ADAPTER} -e #{APP_ENV} \
            -L #{File.join(APP_ROOT, "/current/log/#{APP_ENV}.log")} -m #{File.join(APP_ROOT, "/current")} \
            -c #{CLUSTER_NODES} -P '#{File.join(APP_PIDS, "production-merb.%s.pid")}' -p #{CLUSTER_PORT}"
            
  w.stop = "merb -K all -e #{APP_ENV} -m #{File.join(APP_ROOT, "/current")} \
            -P '#{File.join(APP_PIDS, "production-merb.%s.pid")}'"
  
  w.behavior(:clean_pid_file)
  
  [*CLUSTER_PORT ... (CLUSTER_PORT + CLUSTER_NODES)].each do |worker_port|
    merb_worker(worker_port)
  end
  
  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 = 150.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.retry_in = 10.minutes
      c.retry_times = 5
      c.retry_within = 2.hours
    end
  end
end