lib/god/process.rb

   1 require 'fileutils'
   2
   3 module God
   4   class Process
   5     WRITES_PID = [:start, :restart]
   6
   7     attr_accessor :name, :uid, :gid, :start, :stop, :restart
   8
   9     def initialize(options={})
  10       options.each do |k,v|
  11         send("#{k}=", v)
  12       end
  13
  14       @tracking_pid = false
  15     end
  16
  17     # DON'T USE THIS INTERNALLY. Use the instance variable. -- Kev
  18     # No really, trust me. Use the instance variable.
  19     def pid_file=(value)
  20       @tracking_pid = false
  21       @pid_file = value
  22     end
  23
  24     def pid_file
  25       if @pid_file.nil?
  26         @tracking_pid = true
  27         @pid_file = default_pid_file
  28       end
  29       @pid_file
  30     end
  31
  32     def start!
  33       call_action(:start)
  34     end
  35
  36     def stop!
  37       call_action(:stop)
  38     end
  39
  40     def restart!
  41       call_action(:restart)
  42     end
  43
  44     def call_action(action)
  45       command = send(action)
  46       if command.kind_of?(String)
  47         # Make pid directory
  48         unless test(?d, God.pid_file_directory)
  49           begin
  50             FileUtils.mkdir_p(God.pid_file_directory)
  51           rescue Errno::EACCES => e
  52             abort"Failed to create pid file directory: #{e.message}"
  53           end
  54         end
  55
  56         unless test(?w, God.pid_file_directory)
  57           abort "The pid file directory (#{God.pid_file_directory}) is not writable by #{Etc.getlogin}"
  58         end
  59
  60         # string command
  61         # fork/exec to setuid/gid
  62         pid = fork {
  63           ::Process.setsid
  64           ::Process::Sys.setgid(Etc.getgrnam(self.gid).gid) if self.gid
  65           ::Process::Sys.setuid(Etc.getpwnam(self.uid).uid) if self.uid
  66           Dir.chdir "/"
  67           $0 = command
  68           STDIN.reopen "/dev/null"
  69           STDOUT.reopen "/dev/null", "a"
  70           STDERR.reopen STDOUT
  71           exec command
  72         }
  73
  74         ::Process.detach pid
  75
  76         if @tracking_pid or (@pid_file.nil? and WRITES_PID.include?(action))
  77           File.open(default_pid_file, 'w') do |f|
  78             f.write pid
  79           end
  80
  81           @tracking_pid = true
  82           @pid_file = default_pid_file
  83         end
  84
  85       elsif command.kind_of?(Proc)
  86         # lambda command
  87         command.call
  88       else
  89         raise NotImplementedError
  90       end
  91     end
  92
  93     def default_pid_file
  94       File.join(God.pid_file_directory, "#{self.name}.pid")
  95     end
  96   end
  97 end