Varnish: Make cache dependent on X-Forwarded-Proto https

Question

following situation: On the server is a apache and Varnish for caching. SSL is handled by an amazon load balancer. If the page is requested using https, the http header "X-Forwarded-Proto" is set to "https". The pages are sometimes different (e.g. links/images have to be fetched using https when using a secure connection)

How can I tell varnish that pages are different if the X-Forwarded-Proto header differs? As it is now, whatever is accessed first is cached and served for http and https!

Answer 1

What you want, I presume, is to have different cached versions of the same URI, that's pretty easy using a custom vcl_hash:

sub vcl_hash {
  # ...
  if (req.http.X-Forwarded-Proto &&
      req.url !~ "(?i)\.(png|gif|jpeg|jpg|ico|gz|tgz|bz2|tbz|mp3|ogg|zip|rar|otf|ttf|eot|woff|svg|pdf)$") {
     hash_data(req.http.X-Forwarded-Proto);
  }
  # ...
}

In this example static files are only cached once and the rest (html, js, css..) are cached in 2 different versions (assuming X-Forwarded-Proto only takes two values).

You can see the example in a broader context on https://github.com/NITEMAN/varnish-bites/blob/master/varnish3/drupal-base.vcl