John Yerhot

Though using subdomains is all the rage right now, there are certianly instances where you may want to deploy your rails application to a subdirectory such as:

http://www.johnyerhot.com/myrailsapp

Of course Nginx makes it super easy to do so. If you need to get your webserver ready with Nginx, PHP running as a FCGI instance, and Rails check out my other how to.  

Now, onward!

First create a new virtual host.  In my case, for yerhot.org it would look like this:
server {
listen 80;
server_name yerhot.org;
access_log /var/www/yerhot.org/logs/access.log;
error_log /var/www/yerhot.org/logs/error.log;
location / {
root /var/www/yerhot.org/;
index index.html;
}
}
Pretty simple setup, telling Nginx to listen on port 80 for requests for yerhot.org, where to store logs, and finally setting up the site root at /var/www/yerhot.org.

All we would have to do to have Nginx redirect to our Rails app when looking for yerhot.org/myrailsapp is make another location block (in other words, place this right before the last curly brace).

location /myrailsapp {
proxy_pass http://localhost:8000;
}
Now, all requests for /myrailsapp will get proxied to port 8000. Now fire up your Rails app on port 8000.
mongrel_rails start -e production -p 8000 -d
Restart Nginx:
/etc/init.d/nginx stop
/etc/init.d/nginx start
And….

Crap. Rails is looking for a ‘myrailsapp’ route, which there is none.  No, no, don’t create one - we’ll need to use a little known feature of Mongrel to fix the problem.. the prefix.
Stop Mongrel…
mongrel_rails stop
And try this:
mongrel_rails start -e production -p 8000 -d --prefix=/myrailsapp

And… your app should fire right up. Pretty neat, if you wanted to you could use it forward to a Mongrel Cluster, a FCGI instance of PHP (from my other post), or lots of stuff.