Simple way to replace URLs for proxied websites using mod filter and substitute. more http://gadelkareem.com/2015/01/21/replacing-urls-html-js-mod_proxy-apache-2-2/

Replacing URLs in HTML and JS with mod_proxy on apache 2.2

<VirtualHost *:80>
        ProxyPreserveHost On
        ServerName proxy-test.example.com
        FilterDeclare MYFILTER
        FilterProvider MYFILTER SUBSTITUTE resp=Content-Type $text/
        FilterProvider MYFILTER SUBSTITUTE resp=Content-Type $/xml
        FilterProvider MYFILTER SUBSTITUTE resp=Content-Type $/json
        FilterProvider MYFILTER SUBSTITUTE resp=Content-Type $/javascript
        <Location />
                #disable gzip
                RequestHeader unset Accept-Encoding
                FilterChain MYFILTER
                Substitute "s!(images|static|test).example.com!proxy-$1.example.com!i"
        </Location>
        ProxyPass / http://test.example.com/
        ProxyPassReverse / http://test.example.com/
</VirtualHost>