Apache Port Forward / Reverse Proxy Config

apache-reverse-proxy.conf

# Running some application on port 8080, want to make it
# available at subdomain.example.com
<VirtualHost *:80>
        ServerAdmin webmaster@localhost
        ServerName subdomain.example.com
        ProxyPreserveHost On

            # setup the proxy
            <Proxy *>
                Order allow,deny
                Allow from all
            </Proxy>

            ProxyPass / http://localhost:8080/
            ProxyPassReverse / http://localhost:8080/
</VirtualHost>

The file should get saved at /etc/apache2/mysite.conf

Before doing this, you should run:

a2enmod proxy proxy_ajp proxy_http rewrite deflate headers proxy_balancer proxy_connect proxy_html

After doing this, you should run:

$ a2ensite enable mysite

After that, restart the server.

This worked for me, thanks @alexklibisz