Runit services for heavy-duty Rails hosting

Here's a bunch of scripts for deploying a full production Rails app that runs under runit.

This scheme is currently used to run several large production Rails apps, including looktothesters.org, and it has worked very nicely for a couple of years now. More reliable than system-wide init.d scripts, and fewer permission headaches.

How to use it

Create an unprivileged user for your Rails app, then set up a system-wide Runit service to manage user-specific services for that user -- see this page for details.

All further steps assume that you are working as the unprivileged user.

Now, clone this project into the user's home directory:

cd
git clone git://github.com/purcell/rails-runit.git

Symlink your rails app's root directory to this directory with the name 'app':

ln -s ~appuser/releases/current ~/rails-runit/app

Now you can create some services:

cd ~/rails-runit
./add-mongrel 4001
./add-mongrel 4002
./add-mongrel 4003
./add-haproxy 4000
./add-nginx 4020 4000

This creates (potential) runit services under ~/rails-runit/service. Symlink them to ~/service, and runit will start them for you.

Once started, you can set your system-wide web server to proxy requests for your Rails app to port 4000 (haproxy => mongrel * 3), or to port 4020 (nginx => haproxy => mongrel * 3).

Browse to port 3998 (= haproxy port - 2) to see the haproxy status page.

You can then easily restart your app (e.g. as part of a capistrano deployment) like this:

sv restart ~/service/mongrel-*

Further "add-" and "-run" scripts are provided for varnish and ferret_server.

Status

The haproxy service assumes that the mongrels will be found on the 10 ports higher than itself.

The use of the 'production' RAILS_ENV is hard-coded, so look out for that if you try it on your own machine.

The entire scheme is subject to change -- see below.

Future plans

I'd like to rewrite all this in ruby so we can have templates for the config files in ERB, and to make the port mapping a bit more flexible. The 'run' scripts would then look up their config templates under RAILS_ROOT/config first, and fall back to ~/rails-runit/ if necessary.

It'd be nice to automatically generate monitrc fragments that could be included by a system-wide monit instance for the purposes of monitoring the app.