Fix delete in place of keys in stackdriver output (#5465)

plugins/outputs/stackdriver/stackdriver.go

@@ -199,12 +199,14 @@ func (s *Stackdriver) Write(metrics []telegraf.Metric) error {
 	for len(buckets) != 0 {
 		// can send up to 200 time series to stackdriver
 		timeSeries := make([]*monitoringpb.TimeSeries, 0, 200)
-		for i, k := range keys {
+		for i := 0; i < len(keys); i++ {
+			k := keys[i]
 			s := buckets[k]
 			timeSeries = append(timeSeries, s[0])
 			if len(s) == 1 {
 				delete(buckets, k)
 				keys = append(keys[:i], keys[i+1:]...)
+				i--
 				continue
 			}
 

plugins/outputs/stackdriver/stackdriver_test.go

@@ -253,6 +253,51 @@ func TestWriteBatchable(t *testing.T) {
 			},
 			time.Unix(1, 0),
 		),
+		testutil.MustMetric("ram",
+			map[string]string{
+				"foo": "bar",
+			},
+			map[string]interface{}{
+				"value": 42,
+			},
+			time.Unix(4, 0),
+		),
+		testutil.MustMetric("ram",
+			map[string]string{
+				"foo": "foo",
+			},
+			map[string]interface{}{
+				"value": 43,
+			},
+			time.Unix(5, 0),
+		),
+		testutil.MustMetric("ram",
+			map[string]string{
+				"foo": "bar",
+			},
+			map[string]interface{}{
+				"value": 43,
+			},
+			time.Unix(3, 0),
+		),
+		testutil.MustMetric("disk",
+			map[string]string{
+				"foo": "foo",
+			},
+			map[string]interface{}{
+				"value": 43,
+			},
+			time.Unix(3, 0),
+		),
+		testutil.MustMetric("disk",
+			map[string]string{
+				"foo": "bar",
+			},
+			map[string]interface{}{
+				"value": 43,
+			},
+			time.Unix(1, 0),
+		),
 	}
 
 	err = s.Connect()
@@ -262,7 +307,7 @@ func TestWriteBatchable(t *testing.T) {
 
 	require.Len(t, mockMetric.reqs, 2)
 	request := mockMetric.reqs[0].(*monitoringpb.CreateTimeSeriesRequest)
-	require.Len(t, request.TimeSeries, 2)
+	require.Len(t, request.TimeSeries, 6)
 	ts := request.TimeSeries[0]
 	require.Len(t, ts.Points, 1)
 	require.Equal(t, ts.Points[0].Interval, &monitoringpb.TimeInterval{
@@ -288,6 +333,32 @@ func TestWriteBatchable(t *testing.T) {
 			Int64Value: int64(43),
 		},
 	})
+
+	ts = request.TimeSeries[2]
+	require.Len(t, ts.Points, 1)
+	require.Equal(t, ts.Points[0].Interval, &monitoringpb.TimeInterval{
+		EndTime: &googlepb.Timestamp{
+			Seconds: 3,
+		},
+	})
+	require.Equal(t, ts.Points[0].Value, &monitoringpb.TypedValue{
+		Value: &monitoringpb.TypedValue_Int64Value{
+			Int64Value: int64(43),
+		},
+	})
+
+	ts = request.TimeSeries[4]
+	require.Len(t, ts.Points, 1)
+	require.Equal(t, ts.Points[0].Interval, &monitoringpb.TimeInterval{
+		EndTime: &googlepb.Timestamp{
+			Seconds: 5,
+		},
+	})
+	require.Equal(t, ts.Points[0].Value, &monitoringpb.TypedValue{
+		Value: &monitoringpb.TypedValue_Int64Value{
+			Int64Value: int64(43),
+		},
+	})
 }
 
 func TestWriteIgnoredErrors(t *testing.T) {