// parameter is provided, no bucket metrics are returned.
func (h *metricsV3Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	pathComponents := mux.Vars(r)["pathComps"]
	isListingRequest := r.Form.Has("list")

	var buckets []string
	if strings.HasPrefix(pathComponents, "/bucket/") {
		// bucket specific metrics, extract the bucket name from the path.