Apache - Reverse Proxy and HTTP 302 status message

Question

My team is trying to setup an Apache reverse proxy from a customer's site into one of our web applications.

http://www.example.com/app1/some-path maps to http://internal1.example.com/some-path

Inside our application we use struts and have redirect = true set on certain actions in order to provide certain functionality. The 302 status messages from these re-directs cause the user to break out of the proxy resulting in an error page for the end user.

HTTP/1.1 302 Found Location: http://internal.example.com/some-path/redirect

Is there any way to setup the reverse proxy in apache so that the redirects work correctly?

http://www.example.com/app1/some-path/redirect

Answer 1

There is an article titled Running a Reverse Proxy in Apache that seems to address your problem. It even uses the same example.com and /app1 that you have in your example. Go to the "Configuring the Proxy" section for examples on how to use ProxyPassReverse.

Answer 2

The AskApache article is quite helpful, but in practice I found a combination of Rewrite rules and ProxyPassReverse to be more flexible. So in your case I'd do something like this:

    <VirtualHost example>
       ServerName www.example.com

       ProxyPassReverse /app1/some-path/ http://internal1.example.com/some-path/
       RewriteEngine On
       RewriteRule /app1/(.*)   http://internal1.example.com/some-path$1 [P]

       ...
    </VirtualHost>

I like this better because it gives you finer-grained control over the paths you're proxying for the internal server. In our case we wanted to expose only part of third-party application. Note that this doesn't address hard-coded links in HTML, which the AskApache article covers.

Also, note that you can have multiple ProxyPassReverse lines:

    ProxyPassReverse / http://internal1.example.com/some-path
    ProxyPassReverse / http://internal2.example.com/some-path

I mention this only because another third-party app we were proxying was sending out redirects that didn't include their internal host name, just a different port.

As a final note, keep in mind that Firebug is extremely useful when debugging the redirects.

Answer 3

Try using the AJP connector instead of reverse proxy. Certainly not a trivial change, but I've found that a lot of the URL nightmares go away when using AJP instead of reverse proxy.

Answer 4

Basically, ProxyPassReverse should take care of rewriting the Location header for you, as Kevin Hakanson pointed out.

One pitfall I have encountered is missing the trailing slash in the url argument. Make sure to use:

ProxyPassReverse / http://internal1.example.com/some-path/

(note the trailing slash!)