OTLP Receiver: Only update metadata to WAL when metadata-wal-records feature is enabled (#17472)

OTLP Receiver: Only update metadata to WAL when metadata-wal-records feature is enabled.

---------

Signed-off-by: pipiland2612 <nguyen.t.dang.minh@gmail.com>

storage/remote/otlptranslator/prometheusremotewrite/combined_appender.go

@@ -82,11 +82,12 @@ func NewCombinedAppenderMetrics(reg prometheus.Registerer) CombinedAppenderMetri
 // NewCombinedAppender creates a combined appender that sets start times and
 // updates metadata for each series only once, and appends samples and
 // exemplars for each call.
-func NewCombinedAppender(app storage.Appender, logger *slog.Logger, ingestCTZeroSample bool, metrics CombinedAppenderMetrics) CombinedAppender {
+func NewCombinedAppender(app storage.Appender, logger *slog.Logger, ingestCTZeroSample, appendMetadata bool, metrics CombinedAppenderMetrics) CombinedAppender {
 	return &combinedAppender{
 		app:                            app,
 		logger:                         logger,
 		ingestCTZeroSample:             ingestCTZeroSample,
+		appendMetadata:                 appendMetadata,
 		refs:                           make(map[uint64]seriesRef),
 		samplesAppendedWithoutMetadata: metrics.samplesAppendedWithoutMetadata,
 		outOfOrderExemplars:            metrics.outOfOrderExemplars,
@@ -106,6 +107,7 @@ type combinedAppender struct {
 	samplesAppendedWithoutMetadata prometheus.Counter
 	outOfOrderExemplars            prometheus.Counter
 	ingestCTZeroSample             bool
+	appendMetadata                 bool
 	// Used to ensure we only update metadata and created timestamps once, and to share storage.SeriesRefs.
 	// To detect hash collision it also stores the labels.
 	// There is no overflow/conflict list, the TSDB will handle that part.
@@ -189,17 +191,10 @@ func (b *combinedAppender) appendFloatOrHistogram(ls labels.Labels, meta metadat
 		return err
 	}
 
-	if !exists || series.meta.Help != meta.Help || series.meta.Type != meta.Type || series.meta.Unit != meta.Unit {
-		updateRefs = true
-		// If this is the first time we see this series, set the metadata.
-		_, err := b.app.UpdateMetadata(ref, ls, meta)
-		if err != nil {
-			b.samplesAppendedWithoutMetadata.Add(1)
-			b.logger.Warn("Error while updating metadata from OTLP", "err", err)
-		}
-	}
+	metadataChanged := exists && (series.meta.Help != meta.Help || series.meta.Type != meta.Type || series.meta.Unit != meta.Unit)
 
-	if updateRefs {
+	// Update cache if references changed or metadata changed.
+	if updateRefs || metadataChanged {
 		b.refs[hash] = seriesRef{
 			ref:  ref,
 			ct:   ct,
@@ -208,6 +203,17 @@ func (b *combinedAppender) appendFloatOrHistogram(ls labels.Labels, meta metadat
 		}
 	}
 
+	// Update metadata in storage if enabled and needed.
+	if b.appendMetadata && (!exists || metadataChanged) {
+		// Only update metadata in WAL if the metadata-wal-records feature is enabled.
+		// Without this feature, metadata is not persisted to WAL.
+		_, err := b.app.UpdateMetadata(ref, ls, meta)
+		if err != nil {
+			b.samplesAppendedWithoutMetadata.Add(1)
+			b.logger.Warn("Error while updating metadata from OTLP", "err", err)
+		}
+	}
+
 	b.appendExemplars(ref, ls, es)
 
 	return err

storage/remote/otlptranslator/prometheusremotewrite/combined_appender_test.go

@@ -17,6 +17,7 @@ import (
 	"bytes"
 	"context"
 	"errors"
+	"fmt"
 	"math"
 	"testing"
 	"time"
@@ -412,13 +413,13 @@ func testCombinedAppenderOnTSDB(t *testing.T, ingestCTZeroSample bool) {
 			reg := prometheus.NewRegistry()
 			cappMetrics := NewCombinedAppenderMetrics(reg)
 			app := db.Appender(ctx)
-			capp := NewCombinedAppender(app, logger, ingestCTZeroSample, cappMetrics)
+			capp := NewCombinedAppender(app, logger, ingestCTZeroSample, false, cappMetrics)
 			tc.appendFunc(t, capp)
 			require.NoError(t, app.Commit())
 
 			if tc.extraAppendFunc != nil {
 				app = db.Appender(ctx)
-				capp = NewCombinedAppender(app, logger, ingestCTZeroSample, cappMetrics)
+				capp = NewCombinedAppender(app, logger, ingestCTZeroSample, false, cappMetrics)
 				tc.extraAppendFunc(t, capp)
 				require.NoError(t, app.Commit())
 			}
@@ -501,7 +502,7 @@ func TestCombinedAppenderSeriesRefs(t *testing.T) {
 
 	t.Run("happy case with CT zero, reference is passed and reused", func(t *testing.T) {
 		app := &appenderRecorder{}
-		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
+		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, false, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
 
 		require.NoError(t, capp.AppendSample(seriesLabels.Copy(), floatMetadata, 1, 2, 42.0, nil))
 
@@ -512,109 +513,38 @@ func TestCombinedAppenderSeriesRefs(t *testing.T) {
 			},
 		}))
 
-		require.Len(t, app.records, 6)
+		require.Len(t, app.records, 5)
 		requireEqualOpAndRef(t, "AppendCTZeroSample", 0, app.records[0])
 		ref := app.records[0].outRef
 		require.NotZero(t, ref)
 		requireEqualOpAndRef(t, "Append", ref, app.records[1])
-		requireEqualOpAndRef(t, "UpdateMetadata", ref, app.records[2])
-		requireEqualOpAndRef(t, "AppendCTZeroSample", ref, app.records[3])
-		requireEqualOpAndRef(t, "Append", ref, app.records[4])
-		requireEqualOpAndRef(t, "AppendExemplar", ref, app.records[5])
+		requireEqualOpAndRef(t, "AppendCTZeroSample", ref, app.records[2])
+		requireEqualOpAndRef(t, "Append", ref, app.records[3])
+		requireEqualOpAndRef(t, "AppendExemplar", ref, app.records[4])
 	})
 
 	t.Run("error on second CT ingest doesn't update the reference", func(t *testing.T) {
 		app := &appenderRecorder{}
-		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
+		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, false, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
 
 		require.NoError(t, capp.AppendSample(seriesLabels.Copy(), floatMetadata, 1, 2, 42.0, nil))
 
 		app.appendCTZeroSampleError = errors.New("test error")
 		require.NoError(t, capp.AppendSample(seriesLabels.Copy(), floatMetadata, 3, 4, 62.0, nil))
 
-		require.Len(t, app.records, 5)
+		require.Len(t, app.records, 4)
 		requireEqualOpAndRef(t, "AppendCTZeroSample", 0, app.records[0])
 		ref := app.records[0].outRef
 		require.NotZero(t, ref)
 		requireEqualOpAndRef(t, "Append", ref, app.records[1])
-		requireEqualOpAndRef(t, "UpdateMetadata", ref, app.records[2])
-		requireEqualOpAndRef(t, "AppendCTZeroSample", ref, app.records[3])
-		require.Zero(t, app.records[3].outRef, "the second AppendCTZeroSample returned 0")
-		requireEqualOpAndRef(t, "Append", ref, app.records[4])
-	})
-
-	t.Run("updateMetadata called when meta help changes", func(t *testing.T) {
-		app := &appenderRecorder{}
-		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
-
-		newMetadata := floatMetadata
-		newMetadata.Help = "some other help"
-
-		require.NoError(t, capp.AppendSample(seriesLabels.Copy(), floatMetadata, 1, 2, 42.0, nil))
-		require.NoError(t, capp.AppendSample(seriesLabels.Copy(), newMetadata, 3, 4, 62.0, nil))
-		require.NoError(t, capp.AppendSample(seriesLabels.Copy(), newMetadata, 3, 5, 162.0, nil))
-
-		require.Len(t, app.records, 7)
-		requireEqualOpAndRef(t, "AppendCTZeroSample", 0, app.records[0])
-		ref := app.records[0].outRef
-		require.NotZero(t, ref)
-		requireEqualOpAndRef(t, "Append", ref, app.records[1])
-		requireEqualOpAndRef(t, "UpdateMetadata", ref, app.records[2])
-		requireEqualOpAndRef(t, "AppendCTZeroSample", ref, app.records[3])
-		requireEqualOpAndRef(t, "Append", ref, app.records[4])
-		requireEqualOpAndRef(t, "UpdateMetadata", ref, app.records[5])
-		requireEqualOpAndRef(t, "Append", ref, app.records[6])
-	})
-
-	t.Run("updateMetadata called when meta unit changes", func(t *testing.T) {
-		app := &appenderRecorder{}
-		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
-
-		newMetadata := floatMetadata
-		newMetadata.Unit = "seconds"
-
-		require.NoError(t, capp.AppendSample(seriesLabels.Copy(), floatMetadata, 1, 2, 42.0, nil))
-		require.NoError(t, capp.AppendSample(seriesLabels.Copy(), newMetadata, 3, 4, 62.0, nil))
-		require.NoError(t, capp.AppendSample(seriesLabels.Copy(), newMetadata, 3, 5, 162.0, nil))
-
-		require.Len(t, app.records, 7)
-		requireEqualOpAndRef(t, "AppendCTZeroSample", 0, app.records[0])
-		ref := app.records[0].outRef
-		require.NotZero(t, ref)
-		requireEqualOpAndRef(t, "Append", ref, app.records[1])
-		requireEqualOpAndRef(t, "UpdateMetadata", ref, app.records[2])
-		requireEqualOpAndRef(t, "AppendCTZeroSample", ref, app.records[3])
-		requireEqualOpAndRef(t, "Append", ref, app.records[4])
-		requireEqualOpAndRef(t, "UpdateMetadata", ref, app.records[5])
-		requireEqualOpAndRef(t, "Append", ref, app.records[6])
-	})
-
-	t.Run("updateMetadata called when meta type changes", func(t *testing.T) {
-		app := &appenderRecorder{}
-		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
-
-		newMetadata := floatMetadata
-		newMetadata.Type = model.MetricTypeGauge
-
-		require.NoError(t, capp.AppendSample(seriesLabels.Copy(), floatMetadata, 1, 2, 42.0, nil))
-		require.NoError(t, capp.AppendSample(seriesLabels.Copy(), newMetadata, 3, 4, 62.0, nil))
-		require.NoError(t, capp.AppendSample(seriesLabels.Copy(), newMetadata, 3, 5, 162.0, nil))
-
-		require.Len(t, app.records, 7)
-		requireEqualOpAndRef(t, "AppendCTZeroSample", 0, app.records[0])
-		ref := app.records[0].outRef
-		require.NotZero(t, ref)
-		requireEqualOpAndRef(t, "Append", ref, app.records[1])
-		requireEqualOpAndRef(t, "UpdateMetadata", ref, app.records[2])
-		requireEqualOpAndRef(t, "AppendCTZeroSample", ref, app.records[3])
-		requireEqualOpAndRef(t, "Append", ref, app.records[4])
-		requireEqualOpAndRef(t, "UpdateMetadata", ref, app.records[5])
-		requireEqualOpAndRef(t, "Append", ref, app.records[6])
+		requireEqualOpAndRef(t, "AppendCTZeroSample", ref, app.records[2])
+		require.Zero(t, app.records[2].outRef, "the second AppendCTZeroSample returned 0")
+		requireEqualOpAndRef(t, "Append", ref, app.records[3])
 	})
 
 	t.Run("metadata, exemplars are not updated if append failed", func(t *testing.T) {
 		app := &appenderRecorder{}
-		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
+		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, false, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
 		app.appendError = errors.New("test error")
 		require.Error(t, capp.AppendSample(seriesLabels.Copy(), floatMetadata, 0, 1, 42.0, []exemplar.Exemplar{
 			{
@@ -632,7 +562,7 @@ func TestCombinedAppenderSeriesRefs(t *testing.T) {
 
 	t.Run("metadata, exemplars are updated if append failed but reference is valid", func(t *testing.T) {
 		app := &appenderRecorder{}
-		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
+		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, true, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
 
 		newMetadata := floatMetadata
 		newMetadata.Help = "some other help"
@@ -661,7 +591,7 @@ func TestCombinedAppenderSeriesRefs(t *testing.T) {
 
 	t.Run("simulate conflict with existing series", func(t *testing.T) {
 		app := &appenderRecorder{}
-		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
+		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, false, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
 
 		ls := labels.FromStrings(
 			model.MetricNameLabel, "test_bytes_total",
@@ -688,23 +618,21 @@ func TestCombinedAppenderSeriesRefs(t *testing.T) {
 			},
 		}))
 
-		require.Len(t, app.records, 7)
+		require.Len(t, app.records, 5)
 		requireEqualOpAndRef(t, "AppendCTZeroSample", 0, app.records[0])
 		ref := app.records[0].outRef
 		require.NotZero(t, ref)
 		requireEqualOpAndRef(t, "Append", ref, app.records[1])
-		requireEqualOpAndRef(t, "UpdateMetadata", ref, app.records[2])
-		requireEqualOpAndRef(t, "AppendCTZeroSample", 0, app.records[3])
-		newRef := app.records[3].outRef
+		requireEqualOpAndRef(t, "AppendCTZeroSample", 0, app.records[2])
+		newRef := app.records[2].outRef
 		require.NotEqual(t, ref, newRef, "the second AppendCTZeroSample returned a different reference")
-		requireEqualOpAndRef(t, "Append", newRef, app.records[4])
-		requireEqualOpAndRef(t, "UpdateMetadata", newRef, app.records[5])
-		requireEqualOpAndRef(t, "AppendExemplar", newRef, app.records[6])
+		requireEqualOpAndRef(t, "Append", newRef, app.records[3])
+		requireEqualOpAndRef(t, "AppendExemplar", newRef, app.records[4])
 	})
 
 	t.Run("check that invoking AppendHistogram returns an error for nil histogram", func(t *testing.T) {
 		app := &appenderRecorder{}
-		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
+		capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, false, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
 
 		ls := labels.FromStrings(
 			model.MetricNameLabel, "test_bytes_total",
@@ -713,6 +641,101 @@ func TestCombinedAppenderSeriesRefs(t *testing.T) {
 		err := capp.AppendHistogram(ls, Metadata{}, 4, 2, nil, nil)
 		require.Error(t, err)
 	})
+
+	for _, appendMetadata := range []bool{false, true} {
+		t.Run(fmt.Sprintf("appendMetadata=%t", appendMetadata), func(t *testing.T) {
+			app := &appenderRecorder{}
+			capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, appendMetadata, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
+
+			require.NoError(t, capp.AppendSample(seriesLabels.Copy(), floatMetadata, 1, 2, 42.0, nil))
+
+			if appendMetadata {
+				require.Len(t, app.records, 3)
+				requireEqualOp(t, "AppendCTZeroSample", app.records[0])
+				requireEqualOp(t, "Append", app.records[1])
+				requireEqualOp(t, "UpdateMetadata", app.records[2])
+			} else {
+				require.Len(t, app.records, 2)
+				requireEqualOp(t, "AppendCTZeroSample", app.records[0])
+				requireEqualOp(t, "Append", app.records[1])
+			}
+		})
+	}
+}
+
+// TestCombinedAppenderMetadataChanges verifies that UpdateMetadata is called
+// when metadata fields change (help, unit, or type).
+func TestCombinedAppenderMetadataChanges(t *testing.T) {
+	seriesLabels := labels.FromStrings(
+		model.MetricNameLabel, "test_metric",
+		"foo", "bar",
+	)
+
+	baseMetadata := Metadata{
+		Metadata: metadata.Metadata{
+			Type: model.MetricTypeCounter,
+			Unit: "bytes",
+			Help: "original help",
+		},
+		MetricFamilyName: "test_metric",
+	}
+
+	tests := []struct {
+		name           string
+		modifyMetadata func(Metadata) Metadata
+	}{
+		{
+			name: "help changes",
+			modifyMetadata: func(m Metadata) Metadata {
+				m.Help = "new help text"
+				return m
+			},
+		},
+		{
+			name: "unit changes",
+			modifyMetadata: func(m Metadata) Metadata {
+				m.Unit = "seconds"
+				return m
+			},
+		},
+		{
+			name: "type changes",
+			modifyMetadata: func(m Metadata) Metadata {
+				m.Type = model.MetricTypeGauge
+				return m
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			app := &appenderRecorder{}
+			capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, true, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
+
+			newMetadata := tt.modifyMetadata(baseMetadata)
+
+			require.NoError(t, capp.AppendSample(seriesLabels.Copy(), baseMetadata, 1, 2, 42.0, nil))
+			require.NoError(t, capp.AppendSample(seriesLabels.Copy(), newMetadata, 3, 4, 62.0, nil))
+			require.NoError(t, capp.AppendSample(seriesLabels.Copy(), newMetadata, 3, 5, 162.0, nil))
+
+			// Verify expected operations.
+			require.Len(t, app.records, 7)
+			requireEqualOpAndRef(t, "AppendCTZeroSample", 0, app.records[0])
+			ref := app.records[0].outRef
+			require.NotZero(t, ref)
+			requireEqualOpAndRef(t, "Append", ref, app.records[1])
+			requireEqualOpAndRef(t, "UpdateMetadata", ref, app.records[2])
+			requireEqualOpAndRef(t, "AppendCTZeroSample", ref, app.records[3])
+			requireEqualOpAndRef(t, "Append", ref, app.records[4])
+			requireEqualOpAndRef(t, "UpdateMetadata", ref, app.records[5])
+			requireEqualOpAndRef(t, "Append", ref, app.records[6])
+		})
+	}
+}
+
+func requireEqualOp(t *testing.T, expectedOp string, actual appenderRecord) {
+	t.Helper()
+	require.Equal(t, expectedOp, actual.op)
 }
 
 func requireEqualOpAndRef(t *testing.T, expectedOp string, expectedRef storage.SeriesRef, actual appenderRecord) {
@@ -833,3 +856,82 @@ func (a *appenderRecorder) Rollback() error {
 func (*appenderRecorder) SetOptions(_ *storage.AppendOptions) {
 	panic("not implemented")
 }
+
+func TestMetadataChangedLogic(t *testing.T) {
+	seriesLabels := labels.FromStrings(model.MetricNameLabel, "test_metric", "foo", "bar")
+	baseMetadata := Metadata{
+		Metadata:         metadata.Metadata{Type: model.MetricTypeCounter, Unit: "bytes", Help: "original"},
+		MetricFamilyName: "test_metric",
+	}
+
+	tests := []struct {
+		name           string
+		appendMetadata bool
+		modifyMetadata func(Metadata) Metadata
+		expectWALCall  bool
+		verifyCached   func(*testing.T, metadata.Metadata)
+	}{
+		{
+			name:           "appendMetadata=false, no change",
+			appendMetadata: false,
+			modifyMetadata: func(m Metadata) Metadata { return m },
+			expectWALCall:  false,
+			verifyCached:   func(t *testing.T, m metadata.Metadata) { require.Equal(t, "original", m.Help) },
+		},
+		{
+			name:           "appendMetadata=false, help changes - cache updated, no WAL",
+			appendMetadata: false,
+			modifyMetadata: func(m Metadata) Metadata { m.Help = "changed"; return m },
+			expectWALCall:  false,
+			verifyCached:   func(t *testing.T, m metadata.Metadata) { require.Equal(t, "changed", m.Help) },
+		},
+		{
+			name:           "appendMetadata=true, help changes - cache and WAL updated",
+			appendMetadata: true,
+			modifyMetadata: func(m Metadata) Metadata { m.Help = "changed"; return m },
+			expectWALCall:  true,
+			verifyCached:   func(t *testing.T, m metadata.Metadata) { require.Equal(t, "changed", m.Help) },
+		},
+		{
+			name:           "appendMetadata=true, unit changes",
+			appendMetadata: true,
+			modifyMetadata: func(m Metadata) Metadata { m.Unit = "seconds"; return m },
+			expectWALCall:  true,
+			verifyCached:   func(t *testing.T, m metadata.Metadata) { require.Equal(t, "seconds", m.Unit) },
+		},
+		{
+			name:           "appendMetadata=true, type changes",
+			appendMetadata: true,
+			modifyMetadata: func(m Metadata) Metadata { m.Type = model.MetricTypeGauge; return m },
+			expectWALCall:  true,
+			verifyCached:   func(t *testing.T, m metadata.Metadata) { require.Equal(t, model.MetricTypeGauge, m.Type) },
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			app := &appenderRecorder{}
+			capp := NewCombinedAppender(app, promslog.NewNopLogger(), true, tt.appendMetadata, NewCombinedAppenderMetrics(prometheus.NewRegistry()))
+
+			require.NoError(t, capp.AppendSample(seriesLabels.Copy(), baseMetadata, 1, 2, 42.0, nil))
+
+			modifiedMetadata := tt.modifyMetadata(baseMetadata)
+			app.records = nil
+			require.NoError(t, capp.AppendSample(seriesLabels.Copy(), modifiedMetadata, 1, 3, 43.0, nil))
+
+			hash := seriesLabels.Hash()
+			cached, exists := capp.(*combinedAppender).refs[hash]
+			require.True(t, exists)
+			tt.verifyCached(t, cached.meta)
+
+			updateMetadataCalled := false
+			for _, record := range app.records {
+				if record.op == "UpdateMetadata" {
+					updateMetadataCalled = true
+					break
+				}
+			}
+			require.Equal(t, tt.expectWALCall, updateMetadataCalled)
+		})
+	}
+}

storage/remote/otlptranslator/prometheusremotewrite/metrics_to_prw_test.go

@@ -1067,7 +1067,7 @@ func BenchmarkPrometheusConverter_FromMetrics(b *testing.B) {
 
 											for b.Loop() {
 												app := &noOpAppender{}
-												mockAppender := NewCombinedAppender(app, noOpLogger, false, appMetrics)
+												mockAppender := NewCombinedAppender(app, noOpLogger, false, false, appMetrics)
 												converter := NewPrometheusConverter(mockAppender)
 												annots, err := converter.FromMetrics(context.Background(), payload.Metrics(), settings)
 												require.NoError(b, err)

storage/remote/write_handler.go

@@ -501,6 +501,8 @@ type OTLPOptions struct {
 	// IngestCTZeroSample enables writing zero samples based on the start time
 	// of metrics.
 	IngestCTZeroSample bool
+	// AppendMetadata enables writing metadata to WAL when metadata-wal-records feature is enabled.
+	AppendMetadata bool
 }
 
 // NewOTLPWriteHandler creates a http.Handler that accepts OTLP write requests and
@@ -519,6 +521,7 @@ func NewOTLPWriteHandler(logger *slog.Logger, reg prometheus.Registerer, appenda
 		lookbackDelta:           opts.LookbackDelta,
 		ingestCTZeroSample:      opts.IngestCTZeroSample,
 		enableTypeAndUnitLabels: opts.EnableTypeAndUnitLabels,
+		appendMetadata:          opts.AppendMetadata,
 		// Register metrics.
 		metrics: otlptranslator.NewCombinedAppenderMetrics(reg),
 	}
@@ -561,6 +564,7 @@ type rwExporter struct {
 	lookbackDelta           time.Duration
 	ingestCTZeroSample      bool
 	enableTypeAndUnitLabels bool
+	appendMetadata          bool
 
 	// Metrics.
 	metrics otlptranslator.CombinedAppenderMetrics
@@ -572,7 +576,7 @@ func (rw *rwExporter) ConsumeMetrics(ctx context.Context, md pmetric.Metrics) er
 		Appender: rw.appendable.Appender(ctx),
 		maxTime:  timestamp.FromTime(time.Now().Add(maxAheadTime)),
 	}
-	combinedAppender := otlptranslator.NewCombinedAppender(app, rw.logger, rw.ingestCTZeroSample, rw.metrics)
+	combinedAppender := otlptranslator.NewCombinedAppender(app, rw.logger, rw.ingestCTZeroSample, rw.appendMetadata, rw.metrics)
 	converter := otlptranslator.NewPrometheusConverter(combinedAppender)
 	annots, err := converter.FromMetrics(ctx, md, otlptranslator.Settings{
 		AddMetricSuffixes:                    otlpCfg.TranslationStrategy.ShouldAddSuffixes(),

storage/remote/write_test.go

@@ -921,6 +921,7 @@ func TestOTLPWriteHandler(t *testing.T) {
 		t.Run(testCase.name, func(t *testing.T) {
 			otlpOpts := OTLPOptions{
 				EnableTypeAndUnitLabels: testCase.typeAndUnitLabels,
+				AppendMetadata:          true,
 			}
 			appendable := handleOTLP(t, exportRequest, testCase.otlpCfg, otlpOpts)
 			for _, sample := range testCase.expectedSamples {

web/api/v1/api.go

@@ -348,6 +348,7 @@ func NewAPI(
 			LookbackDelta:           lookbackDelta,
 			IngestCTZeroSample:      ctZeroIngestionEnabled,
 			EnableTypeAndUnitLabels: enableTypeAndUnitLabels,
+			AppendMetadata:          appendMetadata,
 		})
 	}