If you want to run a reverse proxy with apache, you need to have mod_proxy and proxy_http enabled on your webserver. Fortunately, this is really easy to do. Simply run the following commands to enable mod_proxy and proxy_http:
sudo a2enmod mod_proxy
sudo a2enmod proxy_http
a2enmod is an apache script that makes enabling modules very easy. Running the above command will enable mod_proxy and proxy_http on your apache webserver.
