Apache mod_proxy with mod_rewrite Different Server Preserving URL

Question

I would like Apache to work in the following manner:

1. User types user1.app.com into the address bar.
2. DNS has a wildcard that forwards everything to SERVER1
3. SERVER1 has Apache running that will use a rewrite map to map user1 to IP address xxx.xxx.xxx.
4. Apache serves all content from xxx.xxx.xxx, while preserving the URL user1.app.com

I've attempted to do this several ways:

METHOD 1:

RewriteRule ^(.*) http://xxx.xxx.xxx:port/ [P]

RESULT: Redirect Loop, the remote IP is accessed a handful of times (can confirm by looking at logs on remote server). SERVER1's logs show a repetition of the following:

proxy: *: found reverse proxy worker for http://xxx.xxx.xxx/
mod_proxy.c(1020): Running scheme http handler (attempt 0)
mod_proxy_http.c(1973): proxy: HTTP: serving URL http://xxx.xxx.xxx/
proxy_util.c(2011): proxy: HTTP: has acquired connection for (*)
proxy_util.c(2067): proxy: connecting http://xxx.xxx.xxx/ to xxx.xxx.xxx:80
proxy_util.c(2193): proxy: connected / to xxx.xxx.xxx:80
proxy_util.c(2444): proxy: HTTP: fam 2 socket created to connect to *
proxy_util.c(2576): proxy: HTTP: connection complete to xxx.xxx.xxx:80 (xxx.xxx.xxx)
mod_proxy_http.c(1743): proxy: start body send
mod_proxy_http.c(1847): proxy: end body send
proxy_util.c(2029): proxy: HTTP: has released connection for (*)

METHOD 2:

<VirtualHost *:801>
ServerName SERVER1

ProxyRequests Off

ProxyPreserveHost On

<Proxy *:801>
    Order deny,allow
    Allow from localhost
</Proxy>

ProxyPass / http://xxx.xxx.xxx/
ProxyPassReverse / http://xxx.xxx.xxx/
LogLevel debug
</VirtualHost>

and

RewriteRule ^(.*) http://127.0.0.1:801/ [PT]

RESULT: 400 Bad Request With method2, i can go to SERVER1:801 in my browser and everything works as expected.

Any help is GREATLY appreciated! Thanks in advance!

Answer 1

The solution ended up being a combination of several different tools in apache:

• The use of a text file to map each subdomain to the appropriate IP
• The interpolation of environment variables to access the subdomain in the proxy redirection (had to use ProxyPassInterpolateEnv On and the interpolate keyword at the end of the ProxyPass and ProxyPassReverse statements)

Apache:

ProxyRequests Off
ProxyPreserveHost On

<Proxy *>
    Order deny,allow
    Allow from localhost
</Proxy>

RewriteEngine On

ProxyPassInterpolateEnv On
RewriteMap subdomains txt:/directory/clients.txt
RewriteCond %{HTTP_HOST} ^(.*)\.application\.com
RewriteRule ^ - [E=SERVER_NAME:${subdomains:%1}]

RewriteCond %{REQUEST_URI} !(\.[^./]+)$
RewriteCond %{REQUEST_URI} !(.*)/$
RewriteRule ^(.*)$ %{REQUEST_URI}/ [R]

ProxyPass / http://${SERVER_NAME}/ interpolate
ProxyPassReverse / http://${SERVER_NAME}/ interpolate