Why Ruby Daemons.run_proc block was skipped entirely on Ubuntu 12.04

Question

We are trying to to start a daemon with gem daemons on Ubuntu 12.04 and Rails 3.2.12 environment for a ruote worker. Here is the daemon.rb (gem version 1.1.9):

#!/usr/bin/env ruby
require 'daemons'
require 'logger'
  root = Dir.pwd
  Dir.chdir(root)
  file = Dir.pwd + '/ruote_worker.rb' 
  options = {
    :dir_mode   => :normal,
    :dir        => File.join(root, 'amine.log'),
    :log_output => true,
    :backtrace  => true,
    :multiple   => false
  }

  logger = Logger.new('foo.log')
  logger.info('----before daemon----') 

  Daemons.run_proc('ruote_worker', options) do
    # Server loop:
    loop {
      puts '111111111111111'
      logger.info('aaaaaaaaaaaaaaa')
    }
  end

Here is the foo.log:

# Logfile created on 2013-11-10 12:56:12 -0600 by logger.rb/36483
I, [2013-11-10T12:56:12.594196 #26557]  INFO -- : ----before daemon----

Here is the ruote_worker.rb (for testing purpose):

#!/usr/bin/env ruby

require 'logger'
logger = Logger.new('amine.log')

loop do
    logger.info('---amine---')
    puts '*****************************************************  Amine ****************************'
    sleep 5
end

As the log shows, the Daemons.run_proc() block was entirely skipped and not executed at all. We tried Daemons.run_proc() without 'ruote_worker' and Daemons.call() and none of the code inside the block was executed. Somehow the whole block was skipped and never gets executed. How can I make the daemon work? We have limited experience with Ruby daemons gem.

Answer 1

Read through http://daemons.rubyforge.org/ for a good introduction on how to use the daemons gem. Basically, there are two different ways to create a daemon:

• either you have a control script including a Daemons.run_proc call in which you implement the daemon behaviour
• or you have a control script including a Daemons.run call to which you pass the name of another script that contains the daemon implementation

From the looks of what you have already, you were trying to go for the second variant. The following works for me:

# this is daemon.rb
require 'daemons'
Daemons.run('ruote_worker.rb')


# this is ruote_worker.rb
require 'logger'
logger = Logger.new('amine.log')
loop do
  logger.info('--- amine ---')
  puts '*** amine ***'
  sleep 5
end

When you now invoke ruby daemon.rb run (or ruby daemon.rb start) a daemon is started and the script in ruote_worker.rb is executed.