gistfile1.txt

sub vcl_fetch {
        if (!obj.cacheable) {
            pass;
        }
        if ( obj.status == 404 ) {
             restart;
        }
        elseif (req.request == "GET" && obj.http.Content-Type ~ "html" ) {
            esi;  /* Do ESI processing */
            set obj.ttl = 1 h;
        }
}