Do not check for name label, adding new test

Signed-off-by: Pedro Tanaka <pedro.stanaka@gmail.com>

pkg/distributor/distributor.go

@@ -638,7 +638,7 @@ func (d *Distributor) Push(ctx context.Context, req *cortexpb.WriteRequest) (*co
 		if mrc := d.limits.MetricRelabelConfigs(userID); len(mrc) > 0 {
 			l := relabel.Process(cortexpb.FromLabelAdaptersToLabels(ts.Labels), mrc...)
 			if len(l) == 0 {
-				// all labels are gone, therefore the __name__ label is not present, samples will be discarded
+				// all labels are gone, samples will be discarded
 				validation.DiscardedSamples.WithLabelValues(
 					validation.DroppedByRelabelConfiguration,
 					userID,
@@ -659,7 +659,7 @@ func (d *Distributor) Push(ctx context.Context, req *cortexpb.WriteRequest) (*co
 			removeLabel(labelName, &ts.Labels)
 		}
 
-		if len(ts.Labels) == 0 || wasNameLabelRemoved(ts.Labels) {
+		if len(ts.Labels) == 0 {
 			validation.DiscardedExemplars.WithLabelValues(
 				validation.DroppedByUserConfigurationOverride,
 				userID,
@@ -793,19 +793,6 @@ 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

@@ -1102,17 +1102,6 @@ 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,
@@ -1165,22 +1154,59 @@ 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, expectedTimeseriesLen, len(timeseries))
+			assert.Equal(t, 1, len(timeseries))
 			for _, v := range timeseries {
 				assert.Equal(t, tc.expectedSeries, cortexpb.FromLabelAdaptersToLabels(v.Labels))
 			}
 		}
 	}
 }
 
+func TestDistributor_Push_LabelRemoval_RemovingNameLabelWillError(t *testing.T) {
+	ctx := user.InjectOrgID(context.Background(), "user")
+	type testcase struct {
+		inputSeries    labels.Labels
+		expectedSeries labels.Labels
+		removeReplica  bool
+		removeLabels   []string
+	}
+
+	tc := testcase{
+		removeReplica: true,
+		removeLabels:  []string{"__name__"},
+		inputSeries: labels.Labels{
+			{Name: "__name__", Value: "some_metric"},
+			{Name: "cluster", Value: "one"},
+			{Name: "__replica__", Value: "two"},
+		},
+		expectedSeries: labels.Labels{},
+	}
+
+	var err error
+	var limits validation.Limits
+	flagext.DefaultValues(&limits)
+	limits.DropLabels = tc.removeLabels
+	limits.AcceptHASamples = tc.removeReplica
+
+	ds, _, _ := prepare(t, prepConfig{
+		numIngesters:     2,
+		happyIngesters:   2,
+		numDistributors:  1,
+		shardByAllLabels: true,
+		limits:           &limits,
+	})
+
+	// Push the series to the distributor
+	req := mockWriteRequest([]labels.Labels{tc.inputSeries}, 1, 1)
+	_, err = ds[0].Push(ctx, req)
+	require.Error(t, err)
+	assert.Equal(t, "rpc error: code = Code(400) desc = sample missing metric name", err.Error())
+}
+
 func TestDistributor_Push_ShouldGuaranteeShardingTokenConsistencyOverTheTime(t *testing.T) {
 	ctx := user.InjectOrgID(context.Background(), "user")
 	tests := map[string]struct {