Setup mod_proxy on apache http server

So it took some time but I figured out the way to do it. There is one more module which needs to be loaded. This is what the httpd.conf looks like

LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so

<Directory />
    AllowOverride none
    Require all denied
</Directory>

ProxyPass         /ROOT  http://localhost:8080/ROOT
ProxyPassReverse  /ROOT  http://localhost:8080/ROOT

This works for sure. :)

Since it's easy to overlook, pay attention to @muka's comment:

sudo a2enmod proxy  
sudo a2enmod proxy_http  
sudo service apache2 restart

Make sure to enable both modules proxy and proxy_http!