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Daemons provides an easy way to wrap existing ruby scripts (for example a self-written server) to be run as a daemon and to be controlled by simple start/stop/restart commands.
If you want, you can also use daemons to run blocks of ruby code in a daemon process and to control these processes from the main application.
Besides this basic functionality, daemons offers many advanced features like exception backtracing and logging (in case your ruby script crashes) and monitoring and automatic restarting of your processes if they crash.
You can use Daemons in four different ways:
Layout: suppose you have your self-written server myserver.rb:
# this is myserver.rb # it does nothing really useful at the moment loop do sleep(5) end
To use myserver.rb in a production environment, you need to be able to run myserver.rb in the background (this means detach it from the console, fork it in the background, release all directories and file descriptors).
Just create myserver_control.rb like this:
# this is myserver_control.rb require 'rubygems' # if you use RubyGems require 'daemons' Daemons.run('myserver.rb')
And use it like this from the console:
$ ruby myserver_control.rb start
(myserver.rb is now running in the background)
$ ruby myserver_control.rb restart
(...)
$ ruby myserver_control.rb stop
For testing purposes you can even run myserver.rb without forking in the background:
$ ruby myserver_control.rb run
An additional nice feature of Daemons is that you can pass additional arguments to the script that should be daemonized by seperating them by two hyphens:
$ ruby myserver_control.rb start -- --file=anyfile --a_switch another_argument
Layout: suppose you have some code you want to run in the background and control that background process from a script:
# this is your code # it does nothing really useful at the moment loop do sleep(5) end
To run this code as a daemon create myproc_control.rb like this and include your code:
# this is myproc_control.rb require 'rubygems' # if you use RubyGems require 'daemons' Daemons.run_proc('myproc.rb') do loop do sleep(5) end end
And use it like this from the console:
$ ruby myproc_control.rb start
(myproc.rb is now running in the background)
$ ruby myproc_control.rb restart
(...)
$ ruby myproc_control.rb stop
For testing purposes you can even run myproc.rb without forking in the background:
$ ruby myproc_control.rb run
Layout: you have an application my_app.rb that wants to run a bunch of server tasks as daemon processes.
# this is my_app.rb require 'rubygems' # if you use RubyGems require 'daemons' task1 = Daemons.call(:multiple => true) do # first server task loop { conn = accept_conn() serve(conn) } end task2 = Daemons.call do # second server task loop { something_different() } end # the parent process continues to run # we can even control our tasks, for example stop them task1.stop task2.stop exit
Layout: you have an application my_daemon.rb that wants to run as a daemon (but without the ability to be controlled by daemons via start/stop commands)
# this is my_daemons.rb require 'rubygems' # if you use RubyGems require 'daemons' # Initialize the app while we're not a daemon init() # Become a daemon Daemons.daemonize # The server loop loop { conn = accept_conn() serve(conn) }
For further documentation, refer to the module documentation of Daemons.
Download: just go to rubyforge.org/projects/daemons/
Installation with RubyGems:
$ su # gem install daemons
Installation without RubyGems:
$ tar xfz daemons-x.x.x.tar.gz $ cd daemons-x.x.x $ su # ruby setup.rb
For further documentation, refer to the module documentation of Daemons (click on Daemons).
The RDoc documentation is also online at daemons.rubyforge.org
Written 2005-2013 by Thomas Uehlinger <th.uehlinger@gmx.ch>. Anonymous SVN checkout is available with “svn checkout daemons.rubyforge.org/svn/”.
Copyright © 2005-2013 Thomas Uehlinger
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