Set cookie creating issues

[Pinakee BIswas]

Hi,

We have been using Varnish for caching our web pages. We have an 
ecommerce site. Things have been working fine till today but suddenly 
things have started breaking down and I am not sure why. Following is 
the issue:

We use session cookie to store user sessions. The session cookie is 
getting changed as Cached responses from varnish is having set-cookie 
header which is messing up the session cookie. We are using varnish 4.8. 
Following is a snippet of the VCL:


sub vcl_recv {
     # Happens before we check if we have this in cache already.
     #
     # Typically you clean up the request here, removing cookies you 
don't need,
     # rewriting the request, etc.
     set req.backend_hint = uwsgi;

     #if (req.http.cookie ~ "jivaana_country=") {
         # Set the country header
#       set req.http.X-CLIENT-COUNTRY = regsub(req.http.cookie, 
".*jivaana_country=([^;]+);.*", "\1");
#    }

    std.log("ga:" + ga.extract(req.url, mode = keep));
    set req.url = ga.apply(req.url); #  remove Google Analytics parameters

    if (req.method == "GET") {
         if ((req.url !~ "^/accounts/userheader") &&
             (req.url !~ "^/accounts/new-userheader") &&
             (req.url !~ "^/product/recently-viewed") &&
             (req.url !~ "^/product/recommended-products") &&
             (req.url !~ "^/product/addtobasket")) {
                 unset req.http.cookie; # strip the cookies - we don't 
need them
         }
     }

     call devicedetect;
}

sub vcl_backend_response {
     # Happens after we have read the response headers from the backend.
     #
     # Here you clean the response headers, removing silly Set-Cookie 
headers
     # and other mistakes your backend does.
     if (bereq.method == "GET") {
         set beresp.do_esi = true;
         if ((bereq.url !~ "^/accounts/userheader") &&
             (bereq.url !~ "^/accounts/new-userheader") &&
             (bereq.url !~ "^/product/recently-viewed") &&
             (bereq.url !~ "^/product/recommended-products") &&
             (bereq.url !~ "^/product/addtobasket")) {
                 #unset beresp.http.Set-Cookie;
                 set beresp.uncacheable = false;
                 #std.log("Caching the url : **********************" + 
bereq.url);
    }
}

sub vcl_deliver {
     # Happens when we have all the pieces we need, and are about to 
send the
     # response to the client.
     #
     # You can do accounting or modifying the final object here.
}

sub vcl_hash {
}

Would really appreciate any support as this is messing up our user sessions.

Thanks,

Pinakee