it doesn't look like vulcan supports HTTPS, so it's a no-go for anything serious. Here's a post on my confd/nginx/docker setup for zero-downtime using etcd. http://brianketelsen.com/2014/02/25/using-nginx-confd-and-do...
In our case, HTTPS isn't an issue but there are good arguments for using a tried-and-true proxy. I see Vulcan as a quick way to test out docker containers for our architecture.
In the end I'll probably use confd to rewrite a VCL file for Varnish. It's just a matter of deciding how many containers and what level of sidekicking/ambassadoring I'm willing to put up with to "properly" organize things...
https://github.com/mailgun/vulcan/issues/31
Vulcand should not be used as for anything frontend-related