infra-map/varnish/includes/x-cache-header.vcl

sub vcl_recv {
        unset req.http.X-Cache;
}

sub vcl_hit {
        set req.http.X-Cache = "HIT";
}

sub vcl_miss {
        set req.http.X-Cache = "MISS";
}

sub vcl_pass {
        set req.http.X-Cache = "PASS";
}

sub vcl_pipe {
        set req.http.X-Cache = "PIPE uncacheable";
}

sub vcl_synth {
        set resp.http.X-Cache = "SYNTH";
}

sub vcl_deliver {
        if (obj.uncacheable) {
                set req.http.X-Cache = req.http.X-Cache + " uncacheable" ;
        } else {
                set req.http.X-Cache = req.http.X-Cache + " cached" + " (real age: " + resp.http.Age + ", hits: " + obj.hits + ", ttl: " + resp.http.x-ttl + ")";
        }

        # if we are gracing, make sure the browser doesn't cache things, and set our maxage to 1
        # also log grace delivery
        if (req.http.graceineffect) {
                set resp.http.Cache-Control = regsub(resp.http.Cache-Control, "max-age=[0-9]*", "max-age=1");
                set resp.http.Cache-Control = regsub(resp.http.Cache-Control, "channel-maxage=[0-9]*", "channel-maxage=1");
                set req.http.X-Cache = req.http.X-Cache + " [grace: " + req.http.graceineffect + " " + req.http.grace + ", remaining: " + req.http.graceduration + "]";
        }

        # uncomment the following line to show the information in the response
        set resp.http.X-Cache = req.http.X-Cache;
}