Here we override the TTL of a object comming from the backend if it matches certain criteria:
sub vcl_fetch {
if (req.url ~ "\.(png|gif|jpg)$") {
unset beresp.http.set-cookie;
set beresp.ttl = 1h;
}
}
We also remove any Set-Cookie headers in order to avoid a hit-for-pass object to be created. See user-guide-vcl_actions.