A high traffic site I host for a client needed to be available on both HTTP and HTTPS. This particular site, though, needed different caches depending on what scheme was used.
Note: Since Varnish doesn’t support HTTPS, it is in this case placed behind Nginx. Nginx then indicates any HTTPS requests passed onto by setting the X-Forwarded-Proto header.
With Varnish handling caching, this is what needed to be added to the configuration: