Dæmons

README.md

Hay un montón de cambios para hacer, cosas por mejorar, etc, pero básicamente anda :)

daemon.rb

module Daemon
  @running = false
  @pidfile = nil
  @stdin   = nil
  @stdout  = nil
  @stderr  = nil

  def daemonize!
    Process.daemon true
  end

  def chdir! path
    Dir.chdir File.absolute_path(path)
  end

  def pid_file path
    @pid_file = File.absolute_path(path)
  end

  def stdin path
    @stdin = File.absolute_path(path)
    STDIN.reopen @stdin
  end

  def stdout path
    @stdout = File.absolute_path(path)
    STDOUT.reopen @stdout, "a"
  end

  def stderr path
    @stderr = File.absolute_path(path)
    STDERR.reopen @stderr, "a"
  end

  def running?
    @running
  end

  def start!
    if @pid_file && File.exists?(@pid_file)
      pid = File.read(@pid_file).strip
      begin
        Process.kill 0, pid.to_i
        STDERR.puts "Daemon is already running with PID #{pid}"
        exit 2
      rescue Errno::ESRCH
        run!
      end
    else
      run!
    end
  end

  def run!
    save_pid_file
    @running = true
    trap(:INT) { @running = false; stop }
    run
  end

  def stop!
    if @pid_file && File.exists?(@pid_file)
      pid = File.read(@pid_file).strip
      begin
        Process.kill :INT, pid.to_i
      rescue Errno::ESRCH
        STDERR.puts "No daemon is running with PID #{pid}"
        exit 3
      end
    else
      STDERR.puts "Couldn't find a PID file"
      exit 1
    end
  end

  def stop; end

  def cli
    {
      "-D"   => self.method(:daemonize!),
      "-C"   => self.method(:chdir!),
      "-P"   => self.method(:pid_file),
      "-out" => self.method(:stdout),
      "-err" => self.method(:stderr),
      "-in"  => self.method(:stdin)
    }
  end

  def daemon_usage
    <<-USAGE
Daemon introduced command line arguments:

  -D    Daemonize this process
  -C    Change directory.
  -P    Path to PID file. Only used in daemonized process.
  -out  Path to redirect STDOUT.
  -err  Path to redirect STDERR.
  -in   Path to redirect STDIN.
    USAGE
  end

  private

  def save_pid_file
    File.open(@pid_file, "w") do |fp|
      fp.write(Process.pid)
    end if @pid_file
  end
end

documents.rb

#! /usr/bin/env ruby

require "clap"
require_relative "daemon"

module DW
  extend Daemon

  def self.run
    while running?
      puts Process.pid
      puts Dir.pwd
      sleep 1
    end
  end

  def self.usage
    puts <<-USAGE
#{$0} [options] (start|stop)

  start Starts the daemon
  stop  Stop a running daemon

#{daemon_usage}
    USAGE

    exit
  end

  def self.cli
    super.merge("-h" => DW.method(:usage))
  end
end

case Clap.run(ARGV, DW.cli).first
when "start"
  DW.start!
when "stop"
  DW.stop!
else
  DW.usage
end