How to make Varnish ignore, not delete cookies [closed]

Answer 1

Only sessions are unique to every client, not necessarily cookies.

What you want makes sense and is possible with Varnish, it is just a matter of carefully crafting your own vcl. Please pay attention to the following parts of the default.vcl:

sub vcl_recv {
    ...
    if (req.http.Authorization || req.http.Cookie) {
      /* Not cacheable by default */
      return (pass);
    }
}


sub vcl_hit {
    if (!obj.cacheable) {
        return (pass);
    }
    ...
}


sub vcl_fetch {
    if (!beresp.cacheable) {
        return (pass);
    }
    if (beresp.http.Set-Cookie) {
        return (pass);
    }
    ...
}

You have to replace these parts with your own logic; i.e. define your own vcl_ functions. By default, requests (vcl_recv) and responses (vcl_fetch) with cookies are not cacheable. You know your back-end application best and you should rewrite the generic caching logic to this specific case. That is, you should define in which case varnish does a lookup, pass or deliver.

In your case, you will have pages (case 1 and 2) without a vary-by cookie, which will be cached and shared by everyone (requests with/without cookies); just don't mind req.http.Cookie in vcl_recv. I wouldn't cache pages (case 3) with a vary-by cookie -or at least not for a long time-, as they can not be shared at all; do a 'pass' in vcl_fetch.