Ruby Forum Mongrel > best practices for monitoring mongrels with monit?

Hello,

We're interested in hearing from folks who have worked out a set of 
"best
practices" for monitoring mongrels with monit.

My local setup is remarkably similar to the one currently found in the "
Practical Programmers Deploying Rails Apps Beta" PDF, as well as several
other examples that we've seen floating around on the web.

Has someone gone to the trouble to do a pro/con analysis of a couple of
different approaches, so that we can get a better idea of what folks 
have
tried?

[We'd be sort of miserable if we didn't have monit... it allows us to 
build
some beautiful things!]

thanks very much in advance,

--elijah

Here is a good recipe for a mongrel process, as provided on some site I 
found:

(I believe the forum post was by Ezra)

check process mongrel_cluster_8000
   with pidfile /var/apps/twocb/shared/pids/mongrel.8000.pid
   start program = "/usr/bin/mongrel_rails cluster::start -C 
/var/apps/twocb/current/config/mongrel_cluster.yml --clean --only 8000"
   stop program = "/usr/bin/mongrel_rails cluster::stop -C 
/var/apps/twocb/current/config/mongrel_cluster.yml --clean --only 8000"
   if totalmem is greater than 110.0 MB for 4 cycles then  restart
# eating up memory?
   if cpu is greater than 50% for 2 cycles then  alert
 # send an email to admin
   if cpu is greater than 80% for 3 cycles then  restart
# hung process?
   if loadavg(5min) greater than 10 for 8 cycles then  restart
# bad, bad, bad
   if 20 restarts within 20 cycles then timeout
# something is wrong, call the sys-admin
   group mongrel_cluster

Does anyone have any tips for checking to see if the mongrel instance
is responding to HTTP?  I just tried doing this:

if failed host 127.0.0.1 port 8001 protocol http
    with timeout 10 seconds
  then restart

but when I have that code in my monit script it gives me this error:
mongrel_rails_8001' failed protocol test [HTTP] at INET[127.0.0.1:8018] 
via TCP


Thanks for any tips.

Mike

well, something doesn't seem right:

-> mongrel_rails_8001' failed protocol test [HTTP] at
INET[127.0.0.1:8018]
                                                                                                          ^
^^^^^^^^^^^^

127.0.0.1:8018 <- port 8018? or do you want port 8001?

also i leave the host parameter out of the monit config.

   if failed port 8015 protocol http
      with timeout 20 seconds
      then restart

Sorry - I was copying  and pasting from an alert email.    The ports
"do" match up in my monit script

Here's a real example:

#8002
check process mongrel_rails_8002 with pidfile 
/var/run/mongrel/mongrel.8002.pid
  group mongrel
  start program = "/usr/local/bin/ruby /usr/local/bin/mongrel_rails
start -d -e production -a 127.0.0.1 -c /opt/rails/radius --user
mongrel --group mongrel -p 8002 -P /var/run/mongrel/mongrel.8002.pid
-l /var/log/mongrel/mongrel.8002.log"
  stop program  = "/usr/local/bin/ruby /usr/local/bin/mongrel_rails
stop -P /var/run/mongrel/mongrel.8002.pid"
  if totalmem > 100.0 MB for 5 cycles then restart
  if failed host 127.0.0.1 port 8002 protocol http
    with timeout 10 seconds
  then restart

Well, there are a few things to think about.

1. I've got a script that checks nginx with a "success" message.
2. Are you checking if mongrel is up, or rails?
If it's mongrel, you might want to write a custom route so it's not
loading the framework stack every time.
If it's rails, you should create something like a MonitController that
will respond with "success" when asked for the index action.

Doing those things has worked quite well for me so far. Just be sure
to disable the logging in the monit controller so it doesn't fill your
logs.
def logger
end


On Wed, Mar 26, 2008 at 6:09 PM, Michael Engelhart

Thanks Joey -

I have my apache setup to respond "OK" to monit to test my Apache
instances but how do I write my monit script to hit the
MonitController.index action?  Is it the same config as I would use
for Apache?

Thanks
Mike

here's a blog post on suppressing the logging...

"http://www.ruby-forum.com/topic/95146"

here's my bit from my monitrc

******************
if failed port 8000 protocol http and request "/pulse"
     with timeout 10 seconds
     then restart
*******************

  where "pulse" is defined in my routes.rb

Thanks guys - this works great for me.

Much appreciated.

Mike