improve metrics logging

src/ngrok/server/metrics.go

@@ -182,31 +182,35 @@ func NewKeenIoMetrics(batchInterval time.Duration) *KeenIoMetrics {
 			}
 		}()
 
-		batches := make(map[string][]interface{})
+		batch := make(map[string][]interface{})
 		batchTimer := time.Tick(batchInterval)
 
 		for {
 			select {
 			case m := <-k.Metrics:
-				list, ok := batches[m.Collection]
+				list, ok := batch[m.Collection]
 				if !ok {
 					list = make([]interface{}, 0)
 				}
-				batches[m.Collection] = append(list, m.Event)
+				batch[m.Collection] = append(list, m.Event)
 
 			case <-batchTimer:
 				// no metrics to report
-				if len(batches) == 0 {
+				if len(batch) == 0 {
 					continue
 				}
 
-				payload, err := json.Marshal(batches)
+				payload, err := json.Marshal(batch)
 				if err != nil {
-					k.Error("Failed to serialize metrics payload: %v, %v", batches, err)
+					k.Error("Failed to serialize metrics payload: %v, %v", batch, err)
 				} else {
+					for key, val := range batch {
+						k.Debug("Reporting %d metrics for %s", len(val), key)
+					}
+
 					k.AuthedRequest("POST", "/events", bytes.NewReader(payload))
 				}
-				batches = make(map[string][]interface{})
+				batch = make(map[string][]interface{})
 			}
 		}
 	}()
@@ -234,7 +238,7 @@ func (k *KeenIoMetrics) AuthedRequest(method, path string, body *bytes.Reader) (
 	if err != nil {
 		k.Error("Failed to send metric event to keen.io %v", err)
 	} else {
-		k.Info("keen.io processed request in %v sec", time.Since(requestStartAt).Seconds)
+		k.Info("keen.io processed request in %f sec", time.Since(requestStartAt).Seconds())
 		defer resp.Body.Close()
 		if resp.StatusCode != 200 {
 			bytes, _ := ioutil.ReadAll(resp.Body)