HAProxy SSL offloading
HAProxy has been integrated as a frontend for Varnish in order to offload SSL. This way you will still be able to use HTTPS even when Varnish is fronted to Apache or Nginx.
Documentation
The documentation has been updated and is available here:
https://devilbox.readthedocs.io/en/latest/custom-container/enable-varnish.html
Architecture
To get a better understanding of how this is composed, have a look at the diagram