Having worked for CitrusByte for a couple months now, I can safely say that I’m back in the rails business. And with great power comes great responsibility! And who better to handle my responsibility than God Himself! Anyone who has used rails for 5 minutes has (besides create a full and running website in that limited time) felt the woes of deploying and maintaining rails applications.
After about three years, the defacto rails deployment method is nginx + mongrel. Additionally, and quite often, you also have maybe a Merb or Sinatra server running alongside your rails mongrel processes to handle file uploads. That is a lot of background processes running! On a recent personal site I have worked on (and I am still working on), I had a total of six background applications running: nginx, mysql, mongrel (3 of them), sinatra, beanstalkd, and a worker. I used nginx as the web proxy, mongrel for the rails server, sinatra as my upload server, beanstalkd to queue the uploads that went to sinatra, and a worker to process those jobs. That is a lot of processes to maintain!
And any experienced unix administrator knows that processes are bound to fail at one point or another for some reason or another, let it be over-using memory, over-using CPU, hanging, etc. In the past, to manage processes, we’ve had monit. I’ll admit I have very limited experience with monit (though it was a good experience). This time, I decided to go with God, a ruby-based process manager. Its written in Ruby and its configuration is written in ruby so you can take advantage of all the cool ruby features to configure your own personal God!
The reason God is so amazing is because when I’m developing an application that requires 6 processes to run, its tough to manually start/stop them all to test my code! Using God, its a simple start/stop command and I have a whole development server running on my local machine 
Additionally, I use a separate (different paths) God configuration file for production, and it runs it just as well!
God has a great little tutorial on their home page, but the coolest thing about God in my opinion is that it auto-daemonizes scripts that aren’t daemons by default. So a Sinatra server, for example, is not a daemon, but that’s no problem for God, it handles it perfectly!
The big reason this is such a big issue for me is that beanstalkd doesn’t output its PID file anywhere, and although ps aux | grep ‘beanstalkd’ | awk ‘{print $2}’ is the cool kids way of doing things, its a bit too… hackish for me. So I just dropped this watch into my God configuration file:
God.watch do |w|
w.name = 'beanstalkd'
w.interval = 30.seconds
# I do NOT specify the -d parameter which daemonizes beanstalkd.
# I do this so God can make it a daemon for me!
w.start = "beanstalkd -l 0.0.0.0 -p 11300"
w.start_if do |start|
start.condition(:process_running) do |p|
p.interval = 5.seconds
p.running = false
end
end
endAnd God automatically takes care of beanstalkd for me
Anyways, the moral of this post is YOU should take a look at God, and see how easy it can make your process management!
Posted at 2:54 AM |
Written by Mitchell Hashimoto |
1 Comment made.
