After spending entirely too much time batteling with mod_rewrite I figured I would document how I solved my problem.
Basically I wanted different paths for my apis based on the host name. Turns out the hard part was figuring out how to convince apache to rewrite the urls so that Rails would be happy. Here is the entire apache config file (aside from the ssl and assets VirtualHosts):
# Passenger
LoadModule passenger_module /usr/local/lib/ruby/gems/1.9.1/gems/passenger-3.0.18/ext/apache2/mod_passenger.so
PassengerRoot /usr/local/lib/ruby/gems/1.9.1/gems/passenger-3.0.18
PassengerRuby /usr/local/bin/ruby_with_env
<VirtualHost *:80>
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTP_HOST} ^api [NC]
RewriteCond %{REQUEST_URI} !^/api [NC]
RewriteRule ^/(.*) /api/$1 [PT,L,QSA]
</IfModule>
ServerName app.messageradius.com
DocumentRoot /var/www/passenger/current/public
<Directory /var/www/passenger/current/public>
AllowOverride all
Options -MultiViews
</Directory>
</VirtualHost>
The break down:
RewriteCond %{HTTP_HOST} ^api [NC]
This matches any domains that start with “api”
RewriteCond %{REQUEST_URI} !^/api [NC]
This will match any paths that do not start with “/api”
RewriteRule ^/(.*) /api/$1 [PT,L,QSA]
Here is the part that too me so much effort. The options passed into the RewriteRule. You need at least PT and L for Passenger to mangle the url and pass it to your app.
PT - Forces the resulting URI to be passed back to the URL mapping engine for processing of other URI-to-filename translatorsL - Stop the rewriting process immediately and don’t apply any more rules.QSA - Appends any query string from the original request URL to any query string created in the rewrite target.I went ahead an added QSA to merge query parameters. I am not sure it is required, but seems to work.