[ENHANCEMENT] HTTP API: Add url to errors logged while sending response

Give more clues when troubleshooting.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>

web/api/v1/api.go

@@ -1761,7 +1761,7 @@ func (api *API) respond(w http.ResponseWriter, req *http.Request, data interface
 
 	b, err := codec.Encode(resp)
 	if err != nil {
-		level.Error(api.logger).Log("msg", "error marshaling response", "err", err)
+		level.Error(api.logger).Log("msg", "error marshaling response", "url", req.URL, "err", err)
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
@@ -1769,7 +1769,7 @@ func (api *API) respond(w http.ResponseWriter, req *http.Request, data interface
 	w.Header().Set("Content-Type", codec.ContentType().String())
 	w.WriteHeader(http.StatusOK)
 	if n, err := w.Write(b); err != nil {
-		level.Error(api.logger).Log("msg", "error writing response", "bytesWritten", n, "err", err)
+		level.Error(api.logger).Log("msg", "error writing response", "url", req.URL, "bytesWritten", n, "err", err)
 	}
 }