mod_rewrite: rewriting http://$SOMETHING.app.example.com/ to http://www.example.com/app/$SOMETHING

Question

I'm trying to make http://$SOMETHING.app.example.com/ transparently rewrite to http://www.example.com/app/$SOMETHING.

The config below is giving me a 404 and I'm not sure why.

ServerName www.example.com
ServerAlias *.app.example.com

RewriteEngine On
RewriteCond %{HTTP_HOST} (.*).app.example.com
RewriteRule ^/(.*) /app/%1/$1

I'm missing something obvious, what is it?

Edit: let me make this a little clearer.

If I browse to http://www.example.com/app/abc, I get a page. If I browse to http://abc.app.example.com/ I expect to see the same page, but I'm getting a 404 instead.

Edit2: The DNS record for *.app.example.com is already in place and I can see my request in the access log, with the 404 status.

Edit3: After enabling the mod_rewrite log file, it appears that the post-rewrite path is "$DOCROOT/app/abc" which fails because it doesn't exist. This is a Python/WSGI application, I think that has something to do with my problem. For the moment it looks like we'll just use a regular redirect instead.

Answer 1

You need to set a DNS-record for *.app.example.com. to redirect to the IP of the server. I think in your case that will be the same as the one app.example.com.is pointing to.

Edit: I think one of these should do the trick (normally both):

RewriteCond %{HTTP_HOST} !^app\.example\.com
RewriteCond %{HTTP_HOST} ^([^.]+)
RewriteRule ^(.*) /app/%1/$1 [L]

RewriteCond %{HTTP_HOST} ^([^.]+)\.app\.example\.com$
RewriteRule ^/(.*)$           http://www.example.com/app/%1/$1 [L,R]

Answer 2

Perhaps something like:

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.example\.com
RewriteCond %{HTTP_HOST} !^example\.com
RewriteCond %{HTTP_HOST} ^(.)+\.example\.com
RewriteCond %{REQUEST_URI} !^/app/$1
RewriteRule ^(.*)$ app/$1/$2 [L]

Which ensures you're not currently accessing www.example.com or example.com directly; then takes your prefix, checks that you're not currently accessing at the /app directly (or it will loop forever), and then rewrites. This should be transparent..

Elaborated from http://corz.org/serv/tricks/htaccess2.php

Answer 3

We ended up using an external redirect instead.

RewriteCond %{HTTP_HOST} (.*).app.example.com
RewriteRule ^/(.*) http://www.example.com/app/%1/$1 [R]