God进程管理

功能

优点

配置即ruby代码，灵活 可管理后台进程 可动态加载配置 可根据进程消耗资源重启进程 丰富的通知功能，如邮件，campfire等 支持poll和event两种检测模式

缺点

配置复杂，需要ruby背景 文档太少 配置

poll模式：

RAILS_ROOT = "/Users/tom/dev/gravatar2"

%w{8200 8201 8202}.each do |port|
  God.watch do |w|
    w.name = "gravatar2-mongrel-#{port}"
    w.start = "mongrel_rails start -c #{RAILS_ROOT} -p #{port} \
      -P #{RAILS_ROOT}/log/mongrel.#{port}.pid  -d"
    w.stop = "mongrel_rails stop -P #{RAILS_ROOT}/log/mongrel.#{port}.pid"
    w.restart = "mongrel_rails restart -P #{RAILS_ROOT}/log/mongrel.#{port}.pid"
    w.pid_file = File.join(RAILS_ROOT, "log/mongrel.#{port}.pid")
    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 = 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.transition = :unmonitored
    c.retry_in = 10.minutes
    c.retry_times = 5
    c.retry_within = 2.hours
  end
end



end
end

event模式：

RAILS_ROOT = "/Users/tom/dev/gravatar2"

God.watch do |w|
  w.name = "local-3000"
w.start = "mongrel_rails start -c #{RAILS_ROOT} -P #{RAILS_ROOT}/log/mongrel.pid -p 3000 -d"
  w.stop = "mongrel_rails stop -P #{RAILS_ROOT}/log/mongrel.pid"
  w.restart = "mongrel_rails restart -P #{RAILS_ROOT}/log/mongrel.pid"
w.pid_file = File.join(RAILS_ROOT, "log/mongrel.pid")
  # clean pid files before start if necessary
  w.behavior(:clean_pid_file)
# 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
    end
# failsafe
on.condition(:tries) do |c|
  c.times = 5
  c.transition = :start
end



end
# start if process is not running
  w.transition(:up, :start) do |on|
    on.condition(:process_exits)
  end
# restart if memory or cpu is too high
  w.transition(:up, :restart) do |on|
    on.condition(:memory_usage) do |c|
      c.interval = 20
      c.above = 50.megabytes
      c.times = [3, 5]
    end
on.condition(:cpu_usage) do |c|
  c.interval = 10
  c.above = 10.percent
  c.times = [3, 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

操作

god status 查看被监控进程状态
god start|stop|restart 启动关闭重启进程
god load 动态加载配置
god signal 给进程发信号