backend_round_robin rr {
        set backend.set = {
                { "xx.xx.xx.xx", "http" }
                { "xx.xx.xx.xx", "http" }
        };
}


acl purge {
    "localhost";
    "127.0.0.1";
}

# Caching mime types

sub vcl_recv {

        if (req.http.host ~ "example.com") {
                        req.backend = rr;
        }

        if (req.request == "GET" &&  req.url ~ "\.(css|gif|jpg|png|js|bmp|flv|jpeg|ico|mp3|mp4)$") {
                lookup;
        }

        /* Do not cache if request is not GET or HEAD */
        if (req.request != "GET" && req.request != "HEAD") {
                /* Forward to 'lookup' if request is an authorized PURGE request */
                if (req.request == "PURGE") {
                    if (!client.ip ~ purge) {
                        error 405 "Not allowed.";
                    }
                    lookup;
                }
                pipe ;
        }

        /* Do not cache if request contains an Expect header */
        if (req.http.Expect) {
                pipe ;
        }

        /* Varnish doesn't do INM requests so pass it through */
        if (req.http.If-None-Match) {
                pass;
        }

        /* Do not cache when authenticated via HTTP Basic or Digest Authentication */
        if (req.http.Authenticate || req.http.Authorization) {
                pipe ;
        }

        /* Do not cache when authenticated via "__ac" cookies */
        if (req.http.Cookie && req.http.Cookie ~ "__ac_(name|password|persistent)=") {
                pipe;
        }

        if (req.http.Cache-Control ~ "no-cache") {
                 pass;
        }

        if (req.url ~ "account.login") {
                pipe ;
        }

        lookup;
}

sub vcl_fetch {
        # force minimum ttl of 300 seconds
        if (obj.ttl < 300s) {
                set obj.ttl = 300s;
        }
}

# Do the PURGE thing
sub vcl_hit {
        if (req.request == "PURGE") {
                set obj.ttl = 0s;
                error 200 "Purged";
        }
}

sub vcl_miss {

         /* Varnish doesn't do IMS to backend, so if not in cache just pass it through */
        if (req.http.If-Modified-Since) {
                pass;
        }

        if (req.request == "PURGE") {
                error 404 "Not in cache";
        }


}