Checking if user label drop configuration did not drop __name__ label

Signed-off-by: Pedro Tanaka <[email protected]>

Author: pedro-stanaka

pkg/distributor/distributor.go

@@ -659,6 +659,15 @@ func (d *Distributor) Push(ctx context.Context, req *cortexpb.WriteRequest) (*co
 			removeLabel(labelName, &ts.Labels)
 		}
 
+		if len(ts.Labels) == 0 || wasNameLabelRemoved(ts.Labels) {
+			validation.DiscardedExemplars.WithLabelValues(
+				validation.DroppedByUserConfigurationOverride,
+				userID,
+			).Add(float64(len(ts.Samples)))
+
+			continue
+		}
+
 		// We rely on sorted labels in different places:
 		// 1) When computing token for labels, and sharding by all labels. Here different order of labels returns
 		// different tokens, which is bad.
@@ -784,6 +793,19 @@ func (d *Distributor) Push(ctx context.Context, req *cortexpb.WriteRequest) (*co
 	return &cortexpb.WriteResponse{}, firstPartialErr
 }
 
+func wasNameLabelRemoved(labels []cortexpb.LabelAdapter) bool {
+	const nameLabel = "__name__"
+
+	for i := 0; i < len(labels); i++ {
+		pair := labels[i]
+		if pair.Name == nameLabel {
+			return false
+		}
+	}
+
+	return true
+}
+
 func sortLabelsIfNeeded(labels []cortexpb.LabelAdapter) {
 	// no need to run sort.Slice, if labels are already sorted, which is most of the time.
 	// we can avoid extra memory allocations (mostly interface-related) this way.

pkg/distributor/distributor_test.go

@@ -1102,6 +1102,17 @@ func TestDistributor_Push_LabelRemoval(t *testing.T) {
 				{Name: "__name__", Value: "some_metric"},
 			},
 		},
+		// Edge case: remove label __name__ will drop all user metrics
+		{
+			removeReplica: true,
+			removeLabels:  []string{"__name__"},
+			inputSeries: labels.Labels{
+				{Name: "__name__", Value: "some_metric"},
+				{Name: "cluster", Value: "one"},
+				{Name: "__replica__", Value: "two"},
+			},
+			expectedSeries: labels.Labels{},
+		},
 		// Remove multiple labels and replica.
 		{
 			removeReplica: true,
@@ -1154,11 +1165,15 @@ func TestDistributor_Push_LabelRemoval(t *testing.T) {
 		_, err = ds[0].Push(ctx, req)
 		require.NoError(t, err)
 
+		expectedTimeseriesLen := 0
+		if len(tc.expectedSeries) > 0 {
+			expectedTimeseriesLen = 1
+		}
 		// Since each test pushes only 1 series, we do expect the ingester
 		// to have received exactly 1 series
 		for i := range ingesters {
 			timeseries := ingesters[i].series()
-			assert.Equal(t, 1, len(timeseries))
+			assert.Equal(t, expectedTimeseriesLen, len(timeseries))
 			for _, v := range timeseries {
 				assert.Equal(t, tc.expectedSeries, cortexpb.FromLabelAdaptersToLabels(v.Labels))
 			}

pkg/util/validation/validate.go

@@ -59,6 +59,8 @@ const (
 
 	// DroppedByRelabelConfiguration Samples can also be discarded because of relabeling configuration
 	DroppedByRelabelConfiguration = "relabel_configuration"
+	// DroppedByUserConfigurationOverride Samples discarded due to user configuration removing label __name__
+	DroppedByUserConfigurationOverride = "user_label_removal_configuration"
 
 	// The combined length of the label names and values of an Exemplar's LabelSet MUST NOT exceed 128 UTF-8 characters
 	// https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#exemplars