Varnish 4 Hit Miss Header?

Question

Does anyone have an updated hit miss header working for Varnish 4?

Last one I found was for version 3.

https://www.varnish-cache.org/trac/wiki/VCLExampleHitMissHeader#Varnish3.0

Looking for these:

set beresp.http.X-Cacheable = "NO:Not Cacheable"; "NO:Got Session"; "NO:Cache-Control=private"; "YES";

and possibly other useful debug output on why requests were missed.

Answer 1

Yes, I have:

sub vcl_deliver {
    if (obj.hits > 0) { # Add debug header to see if it's a HIT/MISS and the number of hits, disable when not needed
        set resp.http.X-Cache = "HIT";
    } else {
        set resp.http.X-Cache = "MISS";
    }
    # Please note that obj.hits behaviour changed in 4.0, now it counts per objecthead, not per object
    # and obj.hits may not be reset in some cases where bans are in use. See bug 1492 for details.
    # So take hits with a grain of salt
    set resp.http.X-Cache-Hits = obj.hits;
}

A direct translation of the varnish 3 version of the requested headers to varnish 4:

sub vcl_backend_response {

    if (bereq.http.Cookie ~ "(UserID|_session)") {
        set beresp.http.X-Cacheable = "NO:Got Session";
        set beresp.uncacheable = true;
        return (deliver);

    } elsif (beresp.ttl <= 0s) {
        # Varnish determined the object was not cacheable
        set beresp.http.X-Cacheable = "NO:Not Cacheable";

    } elsif (beresp.http.set-cookie) {
        # You don't wish to cache content for logged in users
        set beresp.http.X-Cacheable = "NO:Set-Cookie";
        set beresp.uncacheable = true;
        return (deliver);

    } elsif (beresp.http.Cache-Control ~ "private") {
        # You are respecting the Cache-Control=private header from the backend
        set beresp.http.X-Cacheable = "NO:Cache-Control=private";
        set beresp.uncacheable = true;
        return (deliver);

    } else {
        # Varnish determined the object was cacheable
        set beresp.http.X-Cacheable = "YES";
    }

    # ....

    return(deliver);
}

There is some documentation about upgrading to Varnish 4 that covers this things:

vcl_fetch is now vcl_backend_response

hit_for_pass objects are created using beresp.uncacheable

req.* not available in vcl_backend_response

req.* used to be available in vcl_fetch, but after the split of functionality, you only have 'bereq.*' in vcl_backend_response.