This week we had to move some of our non HTTPS Drupal websites over HTTPS. The task is pretty straightforward. All you need to do is get a SSL certificates from your favorite vendor and configure your web server to use it over port 443. Things get a little complicated if you have layers of services over your web server. In our case we have Varnish. As a reverse proxy engine varnish helps you to reduce your response time by caching responses from your web server and keeping them in RAM. Most of our static content reaches you from varnish.