Apache 2.2 Mod Proxy ProxyPass behavior

Question

I have a server server.example.com which serves Tomcat on port 80 via a ProxyPass/ProxyPassReverse to 8080 and a Drupal site on the same box at server.example.com:8001. If I enter in the port 8001 explicitly, the Drupal site behaves properly, but I need to make it accessible via server.example.com/blog so I created a ProxyPass/ProxyPassReverse for /blog http://server.example.com:8001 which serves the initial page for the Drupal site correctly, but once the form on the home page of Drupal is filled out and submitted, which POSTs to /, the site changes to the Tomcat site, presumably because the / is not relative to the current host on post :8001. How can I get the ProxyPass for /blog to remain persistent so that all subsequent requests remain within the :8001 VirtualHost (Drupal site)?

One thing I tried was with mod_rewrite:

RewriteCond %{HTTP_REFERER} /^blog/.*$
RewriteRule (.*) %{HTTP_HOST}:8001/$1 [L,P,NC]

But that did nothing at all as far as I can tell. I was hoping that if the initial request was for /blog then the referrer would be as well and I could keep requests on the :8001 virtualhost. Perhaps someone can explain why that is flawed.

Answer 1

The problem you are very likely running into is that the documents returned by Drupal include generated links that all reference / instead of /blog. mod_rewrite and proxypass don't do anything to the contents of documents -- they only act upon the request (or, in the case of ProxyPassReverse, on links such as Location: headers in returned content).

To make an application that normally expects to be installed as / operate on a different URL, you need either to :

(a) Configure the application to be aware of the proper base URL. Many applications include such a setting in order to support exactly the situation you have described.

(b) Install some sort of filtering proxy that can modify the content of returned documents. For Apache, mod_proxy_html is made to do exactly this. This is included natively in Apache 2.4 but may need to be installed separately for 2.2.