I have a bunch of Ruby scripts which are long running, I'd like to ensure that every 30 seconds or so these are up.
I normally start the commands by simply ruby script-name.rb
How can I configure monit to look after these scripts?
Update: I tried to follow this method to create a wrapper script which would then launch the ruby process but it did not seem to create the .pid file and typing './wrapper-script stop' did nothing :/
Should I write the pid inside ruby or use a wrapper script to create the pid necessary for monit?
The Monit Wiki has a lot of configuration examples:
http://mmonit.com/wiki/Monit/ConfigurationExamples
Just pick a simple one and modify it according to your needs.
Update: the wrapper script should create the pid for you in this line:
echo $$ > /var/run/xyz.pid;
Did you adapt the script to your needs? Is it executable (chmod +x)? Does it have write permissions for the destination? Maybe post the wrapper you are trying to use so I can help you more.
You don't need to write a wrapper script or try any kind of black magic, just use the Daemons library and you're done.
Imagine that you have a class Worker that has a method "run" that enters an infinite loop reading from a socket or anything like that, here's how you'd write your Daemons wrapper:
# this is file my_worker_control.rb
require 'rubygems'
require 'daemons'
require 'worker'
Daemons.run_proc(:app_name => 'my_worker', :dir_mode => :system, :log_output => true ) do
Worker.run
end
Once the script is done, just call it from your command line or an init.d script:
my_worker_control.rb run|start|stop|restart
This config will generate a "my_worker.pid" file under "/var/run" and you can use monit to watch over the process by using this file.
Modify the file :
/etc/init.d/skeleton
You will need to slightly modify it, and then :
chmod +x /etc/init.d/process_name
sudo update-rc.d process_name defaults
sudo /etc/init.d/process_name (start| stop| reload )
Now just use Monit with the pid at /var/run/process.pid
start location : sudo /etc/init.d/process start
stop location : sudo /etc/init.d/process stop
Cheers
Writing the pid file in your ruby script may be easiest for you (just open a file and write $$ in it). That said, the wrapper script approach should work fine. Does your script have permission to write to a file in /var/run (or wherever you are putting the pidfile)?
As an alternative (to monit), have a look at bluepill.
(Surely out of subject but) as it is about ruby, why don't you use : http://god.rubyforge.org/ ?
Add this line to your ruby script yourapp.rb, that creates a pid file named yourapp.pid
File.open('/somepath/yourapp.pid', 'w') {|f| f.write Process.pid }
Configure Monit to check for the pid in /etc/monit/conf.d/yourapp
check process yourapp with pidfile /somepath/yourapp.pid
来源：https://stackoverflow.com/questions/4651449/monitor-ruby-processes-with-monit