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Resque + god + capistrano recipe

Tonight littl' recipe: configuring a resque worker to be monitored via god

Here are the steps roughly:

  • install god (sudo gem install god)
  • sudo mkdir /etc/god then put the modified master.conf into /etc/god and try god out to see if everything works fine
  • make god reboot ready
    • sudo cp god-service /etc/init.d
    • sudo chmod +x /etc/init.d/god-service
    • sudo update-rc god-service defaults
  • try out your init.d script by calling /etc/init.d/god-service start|stop|status
  • prepare your app resque.god configuration
  • add the god part to your config/deploy.rb

You may want to tweak the deploy.rb to match more closely the expected behaviour.

Also (as suggested earlier on the resque librelist) you can tweak the configuration using ERB to create n workers instead of one here.

cheers,

-- Thibaut

# note - you may need to split into a before-deploy (stop) and after-deploy (start) depending on your setup
desc "Hot-reload God configuration for the Resque worker"
deploy.task :reload_god_config do
sudo "god stop resque"
sudo "god load #{File.join deploy_to, 'current', 'config', 'resque.god'}"
sudo "god start resque"
end
after 'deploy:update_code', 'deploy:update_shared_symlinks'
after 'deploy:update_code', :install_gems
after :deploy, 'deploy:reload_god_config'
#!/bin/bash
#
# god Startup script for god (http://god.rubyforge.org)
#
# chkconfig: - 85 15
# description: God is an easy to configure, easy to extend monitoring \
# framework written in Ruby.
#
CONF_DIR=/etc/god
GOD_BIN=/usr/local/bin/god
RUBY_BIN=/usr/local/bin/ruby
RETVAL=0
# Go no further if config directory is missing.
[ -d "$CONF_DIR" ] || exit 0
case "$1" in
start)
# Create pid directory
$RUBY_BIN $GOD_BIN -c $CONF_DIR/master.conf
RETVAL=$?
;;
stop)
$RUBY_BIN $GOD_BIN terminate
RETVAL=$?
;;
restart)
$RUBY_BIN $GOD_BIN terminate
$RUBY_BIN $GOD_BIN -c $CONF_DIR/master.conf
RETVAL=$?
;;
status)
$RUBY_BIN $GOD_BIN status
RETVAL=$?
;;
*)
echo "Usage: god {start|stop|restart|status}"
exit 1
;;
esac
exit $RETVAL
load "/var/sites/my-app/current/config/resque.god"
God.watch do |w|
w.name = 'resque'
w.interval = 30.seconds
w.env = { 'RAILS_ENV' => 'production',
'QUEUE' => '*' }
w.uid = 'user'
w.gid = 'user'
w.dir = File.expand_path(File.join(File.dirname(__FILE__),'..'))
w.start = "/usr/local/bin/rake resque:work"
w.start_grace = 10.seconds
w.log = File.expand_path(File.join(File.dirname(__FILE__), '..','log','resque-worker.log'))
# restart if memory gets too high
w.transition(:up, :restart) do |on|
on.condition(:memory_usage) do |c|
c.above = 200.megabytes
c.times = 2
end
end
# determine the state on startup
w.transition(:init, { true => :up, false => :start }) do |on|
on.condition(:process_running) do |c|
c.running = true
end
end
# determine when process has finished starting
w.transition([:start, :restart], :up) do |on|
on.condition(:process_running) do |c|
c.running = true
c.interval = 5.seconds
end
# failsafe
on.condition(:tries) do |c|
c.times = 5
c.transition = :start
c.interval = 5.seconds
end
end
# start if process is not running
w.transition(:up, :start) do |on|
on.condition(:process_running) do |c|
c.running = false
end
end
end
@simonc
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simonc commented Jan 16, 2012

Hi,

How does it work when you use this file in multiple apps ? More specifically, what happens when you do god stop resque ?
If you use this in several apps, how god knows that it's the resque process of a given app ?

Thanks

@thbar
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Author

thbar commented Jan 16, 2012

Hi!

instead of naming the god watch resque, name it resque-app-name and do (untested, not sure dashes work etc but the idea is this):

god stop resque-my-app-1
...

and

w.name          = 'resque-my-app-1'

Hope this helps!

-- Thibaut

@simonc
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simonc commented Jan 16, 2012

Ok, that's what I was thinking but I just wanted to know if there was any magic trick :D

Thanks !

@mutru
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mutru commented Aug 29, 2012

I wrote a quick blog post about how I made this work with Bundler / RVM, and also made it a bit more reliable (gracefully kill workers, trying to make sure that the server's in a consistent state after deployment)
http://blog.flowdock.com/2012/08/29/capistrano-god-bundler-resque-configuration/

@scaryguy
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scaryguy commented Apr 1, 2013

Would this work with RVM?

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