Skip attaching __unit__ and __type__ label if exist

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * [FEATURE] StoreGateway: Introduces a new parquet mode. #7046
 * [FEATURE] Distributor: Add a per-tenant flag `-distributor.enable-type-and-unit-labels` that enables adding `__unit__` and `__type__` labels for remote write v2 and OTLP requests. This is a breaking change; the `-distributor.otlp.enable-type-and-unit-labels` flag is now deprecated, operates as a no-op, and has been consolidated into this new flag. #7077
+* [ENHANCEMENT] Distributor: Skip attaching `__unit__` and `__type__` labels when `-distributor.enable-type-and-unit-labels` is enabled, as these are appended from metadata. #7145
 * [ENHANCEMENT] StoreGateway: Add tracings to parquet mode. #7125
 * [ENHANCEMENT] Alertmanager: Upgrade alertmanger to 0.29.0 and add a new incidentIO integration. #7092
 * [ENHANCEMENT] Querier: Add a `-querier.parquet-queryable-shard-cache-ttl` flag to add TTL to parquet shard cache. #7098

pkg/util/push/push.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/go-kit/log/level"
 	"github.com/prometheus/client_golang/exp/api/remote"
+	"github.com/prometheus/common/model"
 	"github.com/prometheus/prometheus/model/labels"
 	"github.com/prometheus/prometheus/schema"
 	"github.com/prometheus/prometheus/util/compression"
@@ -202,7 +203,11 @@ func convertV2RequestToV1(req *cortexpb.PreallocWriteRequestV2, enableTypeAndUni
 		if shouldAttachTypeAndUnitLabels {
 			slb := labels.NewScratchBuilder(lbs.Len() + 2) // for __type__ and __unit__
 			lbs.Range(func(l labels.Label) {
-				slb.Add(l.Name, l.Value)
+				// Skip __type__ and __unit__ labels to prevent duplication,
+				// We append these labels from metadata.
+				if l.Name != model.MetricTypeLabel && l.Name != model.MetricUnitLabel {
+					slb.Add(l.Name, l.Value)
+				}
 			})
 			schema.Metadata{Type: cortexpb.MetadataV2MetricTypeToMetricType(metricType), Unit: unit}.AddToLabels(&slb)
 			slb.Sort()

pkg/util/push/push_test.go

@@ -173,7 +173,7 @@ func Benchmark_convertV2RequestToV1(b *testing.B) {
 }
 
 func Test_convertV2RequestToV1_WithEnableTypeAndUnitLabels(t *testing.T) {
-	symbols := []string{"", "__name__", "test_metric1", "b", "c", "baz", "qux", "d", "e", "foo", "bar", "f", "g", "h", "i", "Test gauge for test purposes", "Maybe op/sec who knows (:", "Test counter for test purposes"}
+	symbols := []string{"", "__name__", "test_metric1", "b", "c", "baz", "qux", "d", "e", "foo", "bar", "f", "g", "h", "i", "Test gauge for test purposes", "Maybe op/sec who knows (:", "Test counter for test purposes", "__type__", "exist type", "__unit__", "exist unit"}
 	samples := []cortexpb.Sample{
 		{
 			Value:       123,
@@ -233,6 +233,52 @@ func Test_convertV2RequestToV1_WithEnableTypeAndUnitLabels(t *testing.T) {
 			},
 			enableTypeAndUnitLabels: true,
 		},
+		{
+			desc: "should be added from metadata when __type__ and __unit__ labels already exist.",
+			v2Req: &cortexpb.PreallocWriteRequestV2{
+				WriteRequestV2: cortexpb.WriteRequestV2{
+					Symbols: symbols,
+					Timeseries: []cortexpb.PreallocTimeseriesV2{
+						{
+							TimeSeriesV2: &cortexpb.TimeSeriesV2{
+								LabelsRefs: []uint32{1, 2, 3, 4, 18, 19, 20, 21},
+								Samples:    samples,
+								Metadata:   cortexpb.MetadataV2{Type: cortexpb.METRIC_TYPE_COUNTER, HelpRef: 15, UnitRef: 16},
+								Exemplars:  []cortexpb.ExemplarV2{{LabelsRefs: []uint32{11, 12}, Value: 1, Timestamp: 1}},
+							},
+						},
+					},
+				},
+			},
+			expectedV1Req: cortexpb.PreallocWriteRequest{
+				WriteRequest: cortexpb.WriteRequest{
+					Timeseries: []cortexpb.PreallocTimeseries{
+						{
+							TimeSeries: &cortexpb.TimeSeries{
+								Labels:  cortexpb.FromLabelsToLabelAdapters(labels.FromStrings("__name__", "test_metric1", "__type__", "counter", "__unit__", "Maybe op/sec who knows (:", "b", "c")),
+								Samples: samples,
+								Exemplars: []cortexpb.Exemplar{
+									{
+										Labels:      cortexpb.FromLabelsToLabelAdapters(labels.FromStrings("f", "g")),
+										Value:       1,
+										TimestampMs: 1,
+									},
+								},
+							},
+						},
+					},
+					Metadata: []*cortexpb.MetricMetadata{
+						{
+							Type:             cortexpb.COUNTER,
+							MetricFamilyName: "test_metric1",
+							Help:             "Test gauge for test purposes",
+							Unit:             "Maybe op/sec who knows (:",
+						},
+					},
+				},
+			},
+			enableTypeAndUnitLabels: true,
+		},
 		{
 			desc: "should not attach unit and type labels when the enableTypeAndUnitLabels is false",
 			v2Req: &cortexpb.PreallocWriteRequestV2{