chore: otel prom metadata translation pass namespace config (#39826)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

Fixing passing metric namespace to the otel metadata translation, so
when provided metric name matches the metric name in metadata

<!--Describe what testing was performed and which tests were added.-->
#### Testing

Added unit test coverage

---------

Co-authored-by: Arthur Silva Sens <[email protected]>

Author: jmichalek132

.chloggen/jm-otel-prom-metadata-translation-pass-namespace-config.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: pkg/translator/prometheusremotewrite
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Fix bug where metric metadata was sent with incorrect metric name if configuration includes 'namespace'"
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [ 39826 ]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user, api]

exporter/prometheusremotewriteexporter/exporter.go

@@ -220,7 +220,7 @@ func (prwe *prwExporter) pushMetricsV1(ctx context.Context, md pmetric.Metrics)
 
 	var m []*prompb.MetricMetadata
 	if prwe.exporterSettings.SendMetadata {
-		m = prometheusremotewrite.OtelMetricsToMetadata(md, prwe.exporterSettings.AddMetricSuffixes)
+		m = prometheusremotewrite.OtelMetricsToMetadata(md, prwe.exporterSettings.AddMetricSuffixes, prwe.exporterSettings.Namespace)
 	}
 	if err != nil {
 		prwe.telemetry.recordTranslationFailure(ctx)
@@ -253,7 +253,6 @@ func (prwe *prwExporter) PushMetrics(ctx context.Context, md pmetric.Metrics) er
 			return prwe.pushMetricsV1(ctx, md)
 		case config.RemoteWriteProtoMsgV2:
 			return prwe.pushMetricsV2(ctx, md)
-
 		default:
 			return fmt.Errorf("unsupported remote-write protobuf message: %v", prwe.RemoteWriteProtoMsg)
 		}

pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go

@@ -42,7 +42,7 @@ func otelMetricTypeToPromMetricType(otelMetric pmetric.Metric) prompb.MetricMeta
 	return prompb.MetricMetadata_UNKNOWN
 }
 
-func OtelMetricsToMetadata(md pmetric.Metrics, addMetricSuffixes bool) []*prompb.MetricMetadata {
+func OtelMetricsToMetadata(md pmetric.Metrics, addMetricSuffixes bool, namespace string) []*prompb.MetricMetadata {
 	resourceMetricsSlice := md.ResourceMetrics()
 
 	metadataLength := 0
@@ -64,7 +64,7 @@ func OtelMetricsToMetadata(md pmetric.Metrics, addMetricSuffixes bool) []*prompb
 				metric := scopeMetrics.Metrics().At(k)
 				entry := prompb.MetricMetadata{
 					Type:             otelMetricTypeToPromMetricType(metric),
-					MetricFamilyName: prometheustranslator.BuildCompliantName(metric, "", addMetricSuffixes),
+					MetricFamilyName: prometheustranslator.BuildCompliantName(metric, namespace, addMetricSuffixes),
 					Unit:             prometheustranslator.BuildCompliantPrometheusUnit(metric.Unit()),
 					Help:             metric.Description(),
 				}

pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go

@@ -152,9 +152,10 @@ func TestOtelMetricTypeToPromMetricType(t *testing.T) {
 func TestOtelMetricsToMetadata(t *testing.T) {
 	ts := uint64(time.Now().UnixNano())
 	tests := []struct {
-		name    string
-		metrics pmetric.Metrics
-		want    []*prompb.MetricMetadata
+		name      string
+		metrics   pmetric.Metrics
+		want      []*prompb.MetricMetadata
+		namespace string
 	}{
 		{
 			name:    "all types§",
@@ -222,10 +223,27 @@ func TestOtelMetricsToMetadata(t *testing.T) {
 				},
 			},
 		},
+		{
+			name:    "gauge_namespace",
+			metrics: GenerateMetricsGauge(),
+			want: []*prompb.MetricMetadata{
+				{
+					Type: prompb.MetricMetadata_GAUGE,
+					MetricFamilyName: prometheustranslator.BuildCompliantName(getIntGaugeMetric(
+						testdata.TestGaugeDoubleMetricName,
+						pcommon.NewMap(),
+						1, ts,
+					), "ns", false),
+					Unit: "bytes_per_second",
+					Help: "gauge description",
+				},
+			},
+			namespace: "ns",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			metaData := OtelMetricsToMetadata(tt.metrics, false)
+			metaData := OtelMetricsToMetadata(tt.metrics, false, tt.namespace)
 
 			for i := 0; i < len(metaData); i++ {
 				assert.Equal(t, tt.want[i].Type, metaData[i].Type)
@@ -237,6 +255,14 @@ func TestOtelMetricsToMetadata(t *testing.T) {
 	}
 }
 
+func GenerateMetricsGauge() pmetric.Metrics {
+	md := testdata.GenerateMetricsOneEmptyInstrumentationLibrary()
+	ilm0 := md.ResourceMetrics().At(0).ScopeMetrics().At(0)
+	ms := ilm0.Metrics()
+	initMetric(ms.AppendEmpty(), testdata.TestGaugeDoubleMetricName, pmetric.MetricTypeGauge, "By/s", "gauge description")
+	return md
+}
+
 func GenerateMetricsAllTypesNoDataPointsHelp() pmetric.Metrics {
 	md := testdata.GenerateMetricsOneEmptyInstrumentationLibrary()
 	ilm0 := md.ResourceMetrics().At(0).ScopeMetrics().At(0)