auto stop spring server

.spring.rb

module DotSpringRb
  MONITOR_INTERVAL = 10*60
  SERVER_KEEP_PERIOD = 30*60

  module_function

  def env
    @env ||= Spring::Env.new
  end

  def start_idle_monitor
    Thread.new do
      alive_at = Time.now
      loop do
        sleep MONITOR_INTERVAL

        now = Time.now
        current_worker_pids = worker_pids(env.pid)
        env.log "[idle_monitor] worker_pids = #{current_worker_pids.join(',')}"

        if current_worker_pids.empty?
          break if alive_at + SERVER_KEEP_PERIOD < now
        else
          alive_at = now
        end
      end

      cleanup_server
    end
  end

  def cleanup_server
    env.log "[idle_monitor] try to stop server"
    execute_spring :stop
    execute_spring :status
  end

  def execute_spring(command)
    require 'open3'

    cmd = "spring #{command}"
    env.log "[idle_monitor] execute: #{cmd}"
    out, err, status = Open3.capture3(cmd)
    env.log "[idle_monitor]   status: #{status.exitstatus}"
    out.each_line {|line| env.log "[idle_monitor]   stdout: #{line}" }
    err.each_line {|line| env.log "[idle_monitor]   stderr: #{line}" }
  end

  def worker_pids(server_pid)
    app_manager_pids = child_pids([server_pid])
    child_pids(app_manager_pids, exclude: %r{/.*?/fsevent_watch })
  end

  def child_pids(parent_pids, exclude: nil)
    return [] if parent_pids.empty?
    `ps ax -o ppid,pid,command`
      .scan(/^\s*(?:#{parent_pids.join('|')})\s+(\d+)\s+(.*)/)
      .map {|pid, command| exclude && exclude =~ command ? nil : pid }
      .compact
  end

  def process_type
    return :server unless env.server_running?
    return :app_manager if env.pid == Process.ppid
    :worker
  end

  def display_process_info
    # p [process_type, $$, $0, env.pid]
  end
end

DotSpringRb.display_process_info
Spring.after_fork do
  DotSpringRb.display_process_info
end
DotSpringRb.start_idle_monitor if DotSpringRb.process_type == :server