Question

I am trying to find out where a cookie is being set.

I am running Varnish cache and want to know where the cookie is being set so I know if I can safely remove it for caching purposes.

The response headers look like this;

HTTP/1.1 200 OK
Server: Apache/2.2.17 (Ubuntu)
Expires: Mon, 05 Dec 2011 15:11:39 GMT
Cache-Control: no-store, max-age=7200
Vary: Accept-Encoding
Content-Type: text/html; charset=UTF-8
X-Session: NO
X-Cacheable: YES
Date: Tue, 04 Dec 2012 15:29:40 GMT
X-Varnish: 1233768756 1233766580
Age: 1081
Via: 1.1 varnish
Connection: keep-alive
X-Cache: HIT

There is no cookie present. But when loading the same page in a browser the headers are the same, I get a cache hit and no cookie in the response headers.

But then the cookie is there all of a sudden, so it must be being somewhere. Even if I remove it it reappears. It even appears in Incognito mode in Chrome. But it is not in the header response.

I have been through all the javascript on the site and cannot find anything, is there any other way of setting a cookie?

Thanks.

Answer 1

If the Set-Cookie header goes through Varnish at some point, you can use varnishlog to find the request URL:

$ varnishlog -b -m 'RxHeader:Set-Cookie.*COOKIENAME'

This will give you a full varnishlog listing for the backend requests, including the TxURL to the backend which tells you what the client asked for when it got Set-Cookie back.