Leonardo Borges

the not so usual geeky stuff

Monit, Thinking Sphinx and RVM

In one of my Rails projects I’m using Sphinx to provide full-text search capabilities. To integrate both worlds I chose Thinking Sphinx, which is just great and so far has met all of my expectations.

Also, as I previously mentioned, I’m using RVM to manage my ruby installations on both my development and production machines and this setup is what motivated this post.

I use Monit to monitor the services running on my production server - nginx, mysql, php - and as of the first deploy of this application, it only made sense to also monitor Sphinx.

In order to create an initialization script, I would need at least a way to start and stop sphinx from the command line, which, using Thinking Sphinx, can be done using these rake tasks:


$ rake thinking_sphinx:stop
$ rake thinking_sphinx:start

It’s worth mentioning now that I don’t run sphinx as root. I run it with the same user my rails application uses. For the purpose of this post, let’s call it deploy.

When I tried using my script I got errors such as these:


Missing the Rails 2.3.5 gem. Please `gem install -v=2.3.5 rails`, update your RAILS_GEM_VERSION setting in config/environment.rb for the Rails version you do have installed, or comment out RAILS_GEM_VERSION to use the latest version installed.


After some digging around I found that the GEM_HOME environment variable for my deploy user wasn’t being set correctly - something to do with rvm, but not quite sure - and to fix this, well, I just had to set it, leaving the final working version of my script somewhat like this - simplified : 
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#! /bin/sh

### BEGIN INIT INFO
### END INIT INFO

set_path="cd /your/rails/app/root; export GEM_HOME=/path/to/your/gems; RAILS_ENV=production;"

case "$1" in
  start)
        echo -n "Starting sphinx: "
                su - deploy -c "$set_path rake ts:start" >> /var/log/sphinx.log 2>&1
        echo "done."
        ;;
  stop)
        echo -n "Stopping sphinx: "
                su - deploy -c "$set_path rake ts:stop" >> /var/log/sphinx.log 2>&1
        echo "done."
        ;;
      *)
            N=/etc/init.d/sphinx
            echo "Usage: $N {start|stop}" >&2
            exit 1
            ;;
esac

exit 0
There are 2 things happening here. First, regardless of the user I’m running this init script as, I drop privileges in order to execute the rake task with my deploy user. Second, I set the GEM_HOME environment variable to stop getting the ‘gem not found’ errors.

After that, monit was able not only to monitor my sphinx instance, but also (re)start/stop it with the correct user.

I’m no Linux wizard so if you wanna suggest improvements to this script, feel free to do so!

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