From 78b1d28174bbb40863710383ef4f97c028cb07da Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Sat, 30 Sep 2023 10:19:03 +0200
Subject: [PATCH 01/20] feat: prometheus remote write send metadata

---
 .../prometheusremotewriteexporter/exporter.go |  9 ++-
 .../prometheusremotewriteexporter/helper.go   | 16 ++++--
 .../otlp_to_openmetrics_metadata.go           | 57 +++++++++++++++++++
 3 files changed, 74 insertions(+), 8 deletions(-)
 create mode 100644 pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go

diff --git a/exporter/prometheusremotewriteexporter/exporter.go b/exporter/prometheusremotewriteexporter/exporter.go
index 865abcc06636..46e8faa77e56 100644
--- a/exporter/prometheusremotewriteexporter/exporter.go
+++ b/exporter/prometheusremotewriteexporter/exporter.go
@@ -130,12 +130,15 @@ func (prwe *prwExporter) PushMetrics(ctx context.Context, md pmetric.Metrics) er
 	case <-prwe.closeChan:
 		return errors.New("shutdown has been called")
 	default:
+
+		m := prometheusremotewrite.OtelMetricsToMetadata(md)
+
 		tsMap, err := prometheusremotewrite.FromMetrics(md, prwe.exporterSettings)
 		if err != nil {
 			err = consumererror.NewPermanent(err)
 		}
 		// Call export even if a conversion error, since there may be points that were successfully converted.
-		return multierr.Combine(err, prwe.handleExport(ctx, tsMap))
+		return multierr.Combine(err, prwe.handleExport(ctx, tsMap, m))
 	}
 }
 
@@ -151,14 +154,14 @@ func validateAndSanitizeExternalLabels(cfg *Config) (map[string]string, error) {
 	return sanitizedLabels, nil
 }
 
-func (prwe *prwExporter) handleExport(ctx context.Context, tsMap map[string]*prompb.TimeSeries) error {
+func (prwe *prwExporter) handleExport(ctx context.Context, tsMap map[string]*prompb.TimeSeries, m []prompb.MetricMetadata) error {
 	// There are no metrics to export, so return.
 	if len(tsMap) == 0 {
 		return nil
 	}
 
 	// Calls the helper function to convert and batch the TsMap to the desired format
-	requests, err := batchTimeSeries(tsMap, prwe.maxBatchSizeBytes)
+	requests, err := batchTimeSeries(tsMap, prwe.maxBatchSizeBytes, m)
 	if err != nil {
 		return err
 	}
diff --git a/exporter/prometheusremotewriteexporter/helper.go b/exporter/prometheusremotewriteexporter/helper.go
index b468609380c8..362ff66cff28 100644
--- a/exporter/prometheusremotewriteexporter/helper.go
+++ b/exporter/prometheusremotewriteexporter/helper.go
@@ -11,7 +11,7 @@ import (
 )
 
 // batchTimeSeries splits series into multiple batch write requests.
-func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int) ([]*prompb.WriteRequest, error) {
+func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int, m []prompb.MetricMetadata) ([]*prompb.WriteRequest, error) {
 	if len(tsMap) == 0 {
 		return nil, errors.New("invalid tsMap: cannot be empty map")
 	}
@@ -20,12 +20,17 @@ func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int)
 	tsArray := make([]prompb.TimeSeries, 0, len(tsMap))
 	sizeOfCurrentBatch := 0
 
+	sizeOfM := 0
+	for _, mi := range m {
+		sizeOfM += mi.Size()
+	}
+
 	i := 0
 	for _, v := range tsMap {
 		sizeOfSeries := v.Size()
 
-		if sizeOfCurrentBatch+sizeOfSeries >= maxBatchByteSize {
-			wrapped := convertTimeseriesToRequest(tsArray)
+		if sizeOfCurrentBatch+sizeOfSeries+sizeOfM >= maxBatchByteSize {
+			wrapped := convertTimeseriesToRequest(tsArray, m)
 			requests = append(requests, wrapped)
 
 			tsArray = make([]prompb.TimeSeries, 0, len(tsMap)-i)
@@ -38,14 +43,14 @@ func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int)
 	}
 
 	if len(tsArray) != 0 {
-		wrapped := convertTimeseriesToRequest(tsArray)
+		wrapped := convertTimeseriesToRequest(tsArray, m)
 		requests = append(requests, wrapped)
 	}
 
 	return requests, nil
 }
 
-func convertTimeseriesToRequest(tsArray []prompb.TimeSeries) *prompb.WriteRequest {
+func convertTimeseriesToRequest(tsArray []prompb.TimeSeries, m []prompb.MetricMetadata) *prompb.WriteRequest {
 	// the remote_write endpoint only requires the timeseries.
 	// otlp defines it's own way to handle metric metadata
 	return &prompb.WriteRequest{
@@ -54,6 +59,7 @@ func convertTimeseriesToRequest(tsArray []prompb.TimeSeries) *prompb.WriteReques
 		// * https://github.com/open-telemetry/wg-prometheus/issues/10
 		// * https://github.com/open-telemetry/opentelemetry-collector/issues/2315
 		Timeseries: orderBySampleTimestamp(tsArray),
+		Metadata:   m,
 	}
 }
 
diff --git a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
new file mode 100644
index 000000000000..b22afe8faa05
--- /dev/null
+++ b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
@@ -0,0 +1,57 @@
+package prometheusremotewrite
+
+import (
+	prometheustranslator "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus"
+	"github.com/prometheus/prometheus/prompb"
+	"go.opentelemetry.io/collector/pdata/pmetric"
+)
+
+func otelMetricTypeToPromMetricType(otelMetric pmetric.Metric) prompb.MetricMetadata_MetricType {
+	switch otelMetric.Type() {
+	case pmetric.MetricTypeGauge:
+		return prompb.MetricMetadata_GAUGE
+	case pmetric.MetricTypeSum:
+		metricType := prompb.MetricMetadata_GAUGE
+		if otelMetric.Sum().IsMonotonic() {
+			metricType = prompb.MetricMetadata_COUNTER
+		}
+		return metricType
+	case pmetric.MetricTypeHistogram:
+		return prompb.MetricMetadata_HISTOGRAM
+	case pmetric.MetricTypeSummary:
+		return prompb.MetricMetadata_SUMMARY
+	case pmetric.MetricTypeExponentialHistogram:
+		return prompb.MetricMetadata_HISTOGRAM
+	}
+	return prompb.MetricMetadata_UNKNOWN
+}
+
+func OtelMetricsToMetadata(md pmetric.Metrics) []prompb.MetricMetadata {
+	resourceMetricsSlice := md.ResourceMetrics()
+
+	metadataLength := 0
+	for i := 0; i < resourceMetricsSlice.Len(); i++ {
+		metadataLength += resourceMetricsSlice.At(i).ScopeMetrics().Len()
+	}
+	var metadata = make([]prompb.MetricMetadata, 0, metadataLength)
+	for i := 0; i < resourceMetricsSlice.Len(); i++ {
+		resourceMetrics := resourceMetricsSlice.At(i)
+		scopeMetricsSlice := resourceMetrics.ScopeMetrics()
+
+		for j := 0; j < scopeMetricsSlice.Len(); j++ {
+			scopeMetrics := scopeMetricsSlice.At(j)
+			for k := 0; k < scopeMetrics.Metrics().Len(); k++ {
+				metric := scopeMetrics.Metrics().At(k)
+				entry := prompb.MetricMetadata{
+					Type:             otelMetricTypeToPromMetricType(metric),
+					MetricFamilyName: prometheustranslator.BuildCompliantName(metric, "", true), // TODO expose addMetricSuffixes in configuration
+					Help:             metric.Description(),
+					Unit:             metric.Unit(),
+				}
+				metadata = append(metadata, entry)
+			}
+		}
+	}
+
+	return metadata
+}

From 14d0c3b662dcd9e060c7f4d61d9c8b1d5c63d176 Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Mon, 9 Oct 2023 22:23:47 +0200
Subject: [PATCH 02/20] chore: added config option for sending medatada

---
 .../prometheusremotewriteexporter/config.go   |  3 +++
 .../prometheusremotewriteexporter/exporter.go | 11 ++++++++---
 .../prometheusremotewriteexporter/helper.go   | 19 ++++++++++++++++---
 .../prometheusremotewrite/metrics_to_prw.go   |  1 +
 .../otlp_to_openmetrics_metadata.go           |  4 ++--
 5 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/exporter/prometheusremotewriteexporter/config.go b/exporter/prometheusremotewriteexporter/config.go
index 22b0b3a969d9..2ceeffcae326 100644
--- a/exporter/prometheusremotewriteexporter/config.go
+++ b/exporter/prometheusremotewriteexporter/config.go
@@ -48,6 +48,9 @@ type Config struct {
 
 	// AddMetricSuffixes controls whether unit and type suffixes are added to metrics on export
 	AddMetricSuffixes bool `mapstructure:"add_metric_suffixes"`
+
+	// AddMetricSuffixes controls whether unit and type suffixes are added to metrics on export
+	SendMetadata bool `mapstructure:"send_metadata"`
 }
 
 type CreatedMetric struct {
diff --git a/exporter/prometheusremotewriteexporter/exporter.go b/exporter/prometheusremotewriteexporter/exporter.go
index 46e8faa77e56..bb94b77d4c5e 100644
--- a/exporter/prometheusremotewriteexporter/exporter.go
+++ b/exporter/prometheusremotewriteexporter/exporter.go
@@ -77,6 +77,7 @@ func newPRWExporter(cfg *Config, set exporter.CreateSettings) (*prwExporter, err
 			DisableTargetInfo:   !cfg.TargetInfo.Enabled,
 			ExportCreatedMetric: cfg.CreatedMetric.Enabled,
 			AddMetricSuffixes:   cfg.AddMetricSuffixes,
+			SendMetadata:        true,
 		},
 	}
 	if cfg.WAL == nil {
@@ -131,14 +132,18 @@ func (prwe *prwExporter) PushMetrics(ctx context.Context, md pmetric.Metrics) er
 		return errors.New("shutdown has been called")
 	default:
 
-		m := prometheusremotewrite.OtelMetricsToMetadata(md)
-
 		tsMap, err := prometheusremotewrite.FromMetrics(md, prwe.exporterSettings)
 		if err != nil {
 			err = consumererror.NewPermanent(err)
 		}
+
+		if prwe.exporterSettings.SendMetadata {
+			m := prometheusremotewrite.OtelMetricsToMetadata(md, prwe.exporterSettings.AddMetricSuffixes)
+			// Call export even if a conversion error, since there may be points that were successfully converted.
+			return multierr.Combine(err, prwe.handleExport(ctx, tsMap, m))
+		}
 		// Call export even if a conversion error, since there may be points that were successfully converted.
-		return multierr.Combine(err, prwe.handleExport(ctx, tsMap, m))
+		return multierr.Combine(err, prwe.handleExport(ctx, tsMap, nil))
 	}
 }
 
diff --git a/exporter/prometheusremotewriteexporter/helper.go b/exporter/prometheusremotewriteexporter/helper.go
index 362ff66cff28..f943622cd8a7 100644
--- a/exporter/prometheusremotewriteexporter/helper.go
+++ b/exporter/prometheusremotewriteexporter/helper.go
@@ -21,8 +21,10 @@ func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int,
 	sizeOfCurrentBatch := 0
 
 	sizeOfM := 0
-	for _, mi := range m {
-		sizeOfM += mi.Size()
+	if m != nil {
+		for _, mi := range m {
+			sizeOfM += mi.Size()
+		}
 	}
 
 	i := 0
@@ -53,13 +55,24 @@ func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int,
 func convertTimeseriesToRequest(tsArray []prompb.TimeSeries, m []prompb.MetricMetadata) *prompb.WriteRequest {
 	// the remote_write endpoint only requires the timeseries.
 	// otlp defines it's own way to handle metric metadata
+
+	if m != nil {
+		return &prompb.WriteRequest{
+			// Prometheus requires time series to be sorted by Timestamp to avoid out of order problems.
+			// See:
+			// * https://github.com/open-telemetry/wg-prometheus/issues/10
+			// * https://github.com/open-telemetry/opentelemetry-collector/issues/2315
+			Timeseries: orderBySampleTimestamp(tsArray),
+			Metadata:   m,
+		}
+	}
+
 	return &prompb.WriteRequest{
 		// Prometheus requires time series to be sorted by Timestamp to avoid out of order problems.
 		// See:
 		// * https://github.com/open-telemetry/wg-prometheus/issues/10
 		// * https://github.com/open-telemetry/opentelemetry-collector/issues/2315
 		Timeseries: orderBySampleTimestamp(tsArray),
-		Metadata:   m,
 	}
 }
 
diff --git a/pkg/translator/prometheusremotewrite/metrics_to_prw.go b/pkg/translator/prometheusremotewrite/metrics_to_prw.go
index 2889a4e9640a..c189f299d037 100644
--- a/pkg/translator/prometheusremotewrite/metrics_to_prw.go
+++ b/pkg/translator/prometheusremotewrite/metrics_to_prw.go
@@ -21,6 +21,7 @@ type Settings struct {
 	DisableTargetInfo   bool
 	ExportCreatedMetric bool
 	AddMetricSuffixes   bool
+	SendMetadata        bool
 }
 
 // FromMetrics converts pmetric.Metrics to prometheus remote write format.
diff --git a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
index b22afe8faa05..852aab1c47e7 100644
--- a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
+++ b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
@@ -26,7 +26,7 @@ func otelMetricTypeToPromMetricType(otelMetric pmetric.Metric) prompb.MetricMeta
 	return prompb.MetricMetadata_UNKNOWN
 }
 
-func OtelMetricsToMetadata(md pmetric.Metrics) []prompb.MetricMetadata {
+func OtelMetricsToMetadata(md pmetric.Metrics, addMetricSuffixes bool) []prompb.MetricMetadata {
 	resourceMetricsSlice := md.ResourceMetrics()
 
 	metadataLength := 0
@@ -44,7 +44,7 @@ func OtelMetricsToMetadata(md pmetric.Metrics) []prompb.MetricMetadata {
 				metric := scopeMetrics.Metrics().At(k)
 				entry := prompb.MetricMetadata{
 					Type:             otelMetricTypeToPromMetricType(metric),
-					MetricFamilyName: prometheustranslator.BuildCompliantName(metric, "", true), // TODO expose addMetricSuffixes in configuration
+					MetricFamilyName: prometheustranslator.BuildCompliantName(metric, "", addMetricSuffixes),
 					Help:             metric.Description(),
 					Unit:             metric.Unit(),
 				}

From 54fc6994404a076c4c93c38a2af180917ae40277 Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Mon, 9 Oct 2023 22:41:34 +0200
Subject: [PATCH 03/20] chore: send metadata in separate requests

---
 .../prometheusremotewriteexporter/exporter.go |  2 +-
 .../prometheusremotewriteexporter/helper.go   | 53 ++++++++++++++-----
 .../otlp_to_openmetrics_metadata.go           |  6 +--
 3 files changed, 44 insertions(+), 17 deletions(-)

diff --git a/exporter/prometheusremotewriteexporter/exporter.go b/exporter/prometheusremotewriteexporter/exporter.go
index bb94b77d4c5e..701a14327c67 100644
--- a/exporter/prometheusremotewriteexporter/exporter.go
+++ b/exporter/prometheusremotewriteexporter/exporter.go
@@ -159,7 +159,7 @@ func validateAndSanitizeExternalLabels(cfg *Config) (map[string]string, error) {
 	return sanitizedLabels, nil
 }
 
-func (prwe *prwExporter) handleExport(ctx context.Context, tsMap map[string]*prompb.TimeSeries, m []prompb.MetricMetadata) error {
+func (prwe *prwExporter) handleExport(ctx context.Context, tsMap map[string]*prompb.TimeSeries, m []*prompb.MetricMetadata) error {
 	// There are no metrics to export, so return.
 	if len(tsMap) == 0 {
 		return nil
diff --git a/exporter/prometheusremotewriteexporter/helper.go b/exporter/prometheusremotewriteexporter/helper.go
index f943622cd8a7..c7187bf004d3 100644
--- a/exporter/prometheusremotewriteexporter/helper.go
+++ b/exporter/prometheusremotewriteexporter/helper.go
@@ -11,28 +11,21 @@ import (
 )
 
 // batchTimeSeries splits series into multiple batch write requests.
-func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int, m []prompb.MetricMetadata) ([]*prompb.WriteRequest, error) {
+func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int, m []*prompb.MetricMetadata) ([]*prompb.WriteRequest, error) {
 	if len(tsMap) == 0 {
 		return nil, errors.New("invalid tsMap: cannot be empty map")
 	}
 
-	requests := make([]*prompb.WriteRequest, 0, len(tsMap))
+	requests := make([]*prompb.WriteRequest, 0, len(tsMap)+len(m))
 	tsArray := make([]prompb.TimeSeries, 0, len(tsMap))
 	sizeOfCurrentBatch := 0
 
-	sizeOfM := 0
-	if m != nil {
-		for _, mi := range m {
-			sizeOfM += mi.Size()
-		}
-	}
-
 	i := 0
 	for _, v := range tsMap {
 		sizeOfSeries := v.Size()
 
-		if sizeOfCurrentBatch+sizeOfSeries+sizeOfM >= maxBatchByteSize {
-			wrapped := convertTimeseriesToRequest(tsArray, m)
+		if sizeOfCurrentBatch+sizeOfSeries >= maxBatchByteSize {
+			wrapped := convertTimeseriesToRequest(tsArray, nil)
 			requests = append(requests, wrapped)
 
 			tsArray = make([]prompb.TimeSeries, 0, len(tsMap)-i)
@@ -45,7 +38,31 @@ func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int,
 	}
 
 	if len(tsArray) != 0 {
-		wrapped := convertTimeseriesToRequest(tsArray, m)
+		wrapped := convertTimeseriesToRequest(tsArray, nil)
+		requests = append(requests, wrapped)
+	}
+
+	mArray := make([]prompb.MetricMetadata, 0, len(m))
+	sizeOfCurrentBatch = 0
+	i = 0
+	for _, v := range m {
+		sizeOfM := v.Size()
+
+		if sizeOfCurrentBatch+sizeOfM >= maxBatchByteSize {
+			wrapped := convertTimeseriesToRequest(nil, mArray)
+			requests = append(requests, wrapped)
+
+			mArray = make([]prompb.MetricMetadata, 0, len(m)-i)
+			sizeOfCurrentBatch = 0
+		}
+
+		mArray = append(mArray, *v)
+		sizeOfCurrentBatch += sizeOfM
+		i++
+	}
+
+	if len(mArray) != 0 {
+		wrapped := convertTimeseriesToRequest(nil, mArray)
 		requests = append(requests, wrapped)
 	}
 
@@ -56,7 +73,7 @@ func convertTimeseriesToRequest(tsArray []prompb.TimeSeries, m []prompb.MetricMe
 	// the remote_write endpoint only requires the timeseries.
 	// otlp defines it's own way to handle metric metadata
 
-	if m != nil {
+	if m != nil && tsArray != nil {
 		return &prompb.WriteRequest{
 			// Prometheus requires time series to be sorted by Timestamp to avoid out of order problems.
 			// See:
@@ -67,6 +84,16 @@ func convertTimeseriesToRequest(tsArray []prompb.TimeSeries, m []prompb.MetricMe
 		}
 	}
 
+	if m != nil {
+		return &prompb.WriteRequest{
+			// Prometheus requires time series to be sorted by Timestamp to avoid out of order problems.
+			// See:
+			// * https://github.com/open-telemetry/wg-prometheus/issues/10
+			// * https://github.com/open-telemetry/opentelemetry-collector/issues/2315
+			Metadata: m,
+		}
+	}
+
 	return &prompb.WriteRequest{
 		// Prometheus requires time series to be sorted by Timestamp to avoid out of order problems.
 		// See:
diff --git a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
index 852aab1c47e7..1ebcaa93f0b7 100644
--- a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
+++ b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
@@ -26,14 +26,14 @@ 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) []*prompb.MetricMetadata {
 	resourceMetricsSlice := md.ResourceMetrics()
 
 	metadataLength := 0
 	for i := 0; i < resourceMetricsSlice.Len(); i++ {
 		metadataLength += resourceMetricsSlice.At(i).ScopeMetrics().Len()
 	}
-	var metadata = make([]prompb.MetricMetadata, 0, metadataLength)
+	var metadata = make([]*prompb.MetricMetadata, 0, metadataLength)
 	for i := 0; i < resourceMetricsSlice.Len(); i++ {
 		resourceMetrics := resourceMetricsSlice.At(i)
 		scopeMetricsSlice := resourceMetrics.ScopeMetrics()
@@ -48,7 +48,7 @@ func OtelMetricsToMetadata(md pmetric.Metrics, addMetricSuffixes bool) []prompb.
 					Help:             metric.Description(),
 					Unit:             metric.Unit(),
 				}
-				metadata = append(metadata, entry)
+				metadata = append(metadata, &entry)
 			}
 		}
 	}

From 3343077a3df2423f3525b9de5d60a2d2ea65c070 Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Sat, 28 Oct 2023 20:57:30 +0200
Subject: [PATCH 04/20] chore: ran make goporto to make the pipeline pass

---
 .../prometheusremotewrite/otlp_to_openmetrics_metadata.go       | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
index 1ebcaa93f0b7..19c282f38151 100644
--- a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
+++ b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
@@ -1,4 +1,4 @@
-package prometheusremotewrite
+package prometheusremotewrite // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheusremotewrite"
 
 import (
 	prometheustranslator "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus"

From 0d27a442930846b7de03b3771970479e0d96ecd8 Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Sat, 28 Oct 2023 22:34:15 +0200
Subject: [PATCH 05/20] chore: add missing license to the file

---
 .../prometheusremotewrite/otlp_to_openmetrics_metadata.go      | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
index 19c282f38151..43ff8c17c3ed 100644
--- a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
+++ b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
@@ -1,3 +1,6 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
 package prometheusremotewrite // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheusremotewrite"
 
 import (

From 44c22dd1a6d5f3c7965394721de0403ceac98e57 Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Sun, 29 Oct 2023 10:51:31 +0100
Subject: [PATCH 06/20] chore: more fixes for pipeline failing

---
 exporter/prometheusremotewriteexporter/exporter_test.go | 4 ++--
 exporter/prometheusremotewriteexporter/helper_test.go   | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/exporter/prometheusremotewriteexporter/exporter_test.go b/exporter/prometheusremotewriteexporter/exporter_test.go
index 2a317cebb91d..9bcfcac1a2a0 100644
--- a/exporter/prometheusremotewriteexporter/exporter_test.go
+++ b/exporter/prometheusremotewriteexporter/exporter_test.go
@@ -368,7 +368,7 @@ func runExportPipeline(ts *prompb.TimeSeries, endpoint *url.URL) error {
 		return err
 	}
 
-	return prwe.handleExport(context.Background(), testmap)
+	return prwe.handleExport(context.Background(), testmap, nil)
 }
 
 // Test_PushMetrics checks the number of TimeSeries received by server and the number of metrics dropped is the same as
@@ -919,7 +919,7 @@ func TestWALOnExporterRoundTrip(t *testing.T) {
 		"timeseries1": ts1,
 		"timeseries2": ts2,
 	}
-	errs := prwe.handleExport(ctx, tsMap)
+	errs := prwe.handleExport(ctx, tsMap, nil)
 	assert.NoError(t, errs)
 	// Shutdown after we've written to the WAL. This ensures that our
 	// exported data in-flight will flushed flushed to the WAL before exiting.
diff --git a/exporter/prometheusremotewriteexporter/helper_test.go b/exporter/prometheusremotewriteexporter/helper_test.go
index 9528607a6fd9..1b838ec0a46b 100644
--- a/exporter/prometheusremotewriteexporter/helper_test.go
+++ b/exporter/prometheusremotewriteexporter/helper_test.go
@@ -57,7 +57,7 @@ func Test_batchTimeSeries(t *testing.T) {
 	// run tests
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			requests, err := batchTimeSeries(tt.tsMap, tt.maxBatchByteSize)
+			requests, err := batchTimeSeries(tt.tsMap, tt.maxBatchByteSize, nil)
 			if tt.returnErr {
 				assert.Error(t, err)
 				return
@@ -116,7 +116,7 @@ func TestEnsureTimeseriesPointsAreSortedByTimestamp(t *testing.T) {
 			},
 		},
 	}
-	got := convertTimeseriesToRequest(outOfOrder)
+	got := convertTimeseriesToRequest(outOfOrder, nil)
 
 	// We must ensure that the resulting Timeseries' sample points are sorted by Timestamp.
 	want := &prompb.WriteRequest{

From afae26f5d952d27f0edbe482f00ba99c7b8070cf Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Sun, 29 Oct 2023 11:35:24 +0100
Subject: [PATCH 07/20] chore: more fixes for pipeline failing

---
 .../prometheusremotewrite/otlp_to_openmetrics_metadata.go      | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
index 43ff8c17c3ed..995465da47f0 100644
--- a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
+++ b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
@@ -4,9 +4,10 @@
 package prometheusremotewrite // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheusremotewrite"
 
 import (
-	prometheustranslator "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus"
 	"github.com/prometheus/prometheus/prompb"
 	"go.opentelemetry.io/collector/pdata/pmetric"
+
+	prometheustranslator "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus"
 )
 
 func otelMetricTypeToPromMetricType(otelMetric pmetric.Metric) prompb.MetricMetadata_MetricType {

From 4663b680de4920e56dcbd07fb32edb855108d00d Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Thu, 9 Nov 2023 12:02:08 +0100
Subject: [PATCH 08/20] chore: disable sending metadata by default

---
 exporter/prometheusremotewriteexporter/exporter.go | 2 +-
 exporter/prometheusremotewriteexporter/factory.go  | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/exporter/prometheusremotewriteexporter/exporter.go b/exporter/prometheusremotewriteexporter/exporter.go
index 701a14327c67..eef1a3c6de92 100644
--- a/exporter/prometheusremotewriteexporter/exporter.go
+++ b/exporter/prometheusremotewriteexporter/exporter.go
@@ -77,7 +77,7 @@ func newPRWExporter(cfg *Config, set exporter.CreateSettings) (*prwExporter, err
 			DisableTargetInfo:   !cfg.TargetInfo.Enabled,
 			ExportCreatedMetric: cfg.CreatedMetric.Enabled,
 			AddMetricSuffixes:   cfg.AddMetricSuffixes,
-			SendMetadata:        true,
+			SendMetadata:        cfg.SendMetadata,
 		},
 	}
 	if cfg.WAL == nil {
diff --git a/exporter/prometheusremotewriteexporter/factory.go b/exporter/prometheusremotewriteexporter/factory.go
index 63135b9b8cb5..f90aa41b21ac 100644
--- a/exporter/prometheusremotewriteexporter/factory.go
+++ b/exporter/prometheusremotewriteexporter/factory.go
@@ -81,6 +81,7 @@ func createDefaultConfig() component.Config {
 			Multiplier:          backoff.DefaultMultiplier,
 		},
 		AddMetricSuffixes: true,
+		SendMetadata:      false,
 		HTTPClientSettings: confighttp.HTTPClientSettings{
 			Endpoint: "http://some.url:9411/api/prom/push",
 			// We almost read 0 bytes, so no need to tune ReadBufferSize.

From dfa93e0f6d1d42bd5e222ec8b20bde79a0bef33c Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Thu, 9 Nov 2023 12:09:41 +0100
Subject: [PATCH 09/20] chore: update remote write exporter readme

---
 exporter/prometheusremotewriteexporter/README.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/exporter/prometheusremotewriteexporter/README.md b/exporter/prometheusremotewriteexporter/README.md
index f15b3c4b76e8..f6dacf9da748 100644
--- a/exporter/prometheusremotewriteexporter/README.md
+++ b/exporter/prometheusremotewriteexporter/README.md
@@ -52,6 +52,7 @@ The following settings can be optionally configured:
   - *Note the following headers cannot be changed: `Content-Encoding`, `Content-Type`, `X-Prometheus-Remote-Write-Version`, and `User-Agent`.*
 - `namespace`: prefix attached to each exported metric name.
 - `add_metric_suffixes`: If set to false, type and unit suffixes will not be added to metrics. Default: true.
+- `send_metadata`: If set to true, prometheus metadata will generated and sent. Default: false.
 - `remote_write_queue`: fine tuning for queueing and sending of the outgoing remote writes.
   - `enabled`: enable the sending queue (default: `true`)
   - `queue_size`: number of OTLP metrics that can be queued. Ignored if `enabled` is `false` (default: `10000`)

From 2c724f90fa05a4b3e88ccd7ed2d39948f776cc45 Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Thu, 9 Nov 2023 15:27:55 +0100
Subject: [PATCH 10/20] chore: added unit tests

---
 .../otlp_to_openmetrics_metadata_test.go      | 234 ++++++++++++++++++
 1 file changed, 234 insertions(+)
 create mode 100644 pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go

diff --git a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go
new file mode 100644
index 000000000000..fee41fbf6291
--- /dev/null
+++ b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go
@@ -0,0 +1,234 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package prometheusremotewrite // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheusremotewrite"
+import (
+	"testing"
+	"time"
+
+	"github.com/prometheus/prometheus/prompb"
+	"github.com/stretchr/testify/assert"
+	"go.opentelemetry.io/collector/pdata/pcommon"
+	"go.opentelemetry.io/collector/pdata/pmetric"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/internal/coreinternal/testdata"
+	prometheustranslator "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus"
+)
+
+func TestOtelMetricTypeToPromMetricType(t *testing.T) {
+	ts := uint64(time.Now().UnixNano())
+	tests := []struct {
+		name   string
+		metric func() pmetric.Metric
+		want   prompb.MetricMetadata_MetricType
+	}{
+		{
+			name: "gauge",
+			metric: func() pmetric.Metric {
+				return getIntGaugeMetric(
+					"test",
+					pcommon.NewMap(),
+					1, ts,
+				)
+			},
+			want: prompb.MetricMetadata_GAUGE,
+		},
+		{
+			name: "sum",
+			metric: func() pmetric.Metric {
+				return getIntSumMetric(
+					"test",
+					pcommon.NewMap(),
+					pmetric.AggregationTemporalityCumulative,
+					1, ts,
+				)
+			},
+			want: prompb.MetricMetadata_GAUGE,
+		},
+		{
+			name: "monotonic cumulative",
+			metric: func() pmetric.Metric {
+				metric := pmetric.NewMetric()
+				metric.SetName("test_sum")
+				metric.SetEmptySum().SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
+				metric.SetEmptySum().SetIsMonotonic(true)
+
+				dp := metric.Sum().DataPoints().AppendEmpty()
+				dp.SetDoubleValue(1)
+
+				return metric
+			},
+			want: prompb.MetricMetadata_COUNTER,
+		},
+		{
+			name: "cumulative histogram",
+			metric: func() pmetric.Metric {
+				m := getHistogramMetric("", pcommon.NewMap(), pmetric.AggregationTemporalityCumulative, 0, 0, 0, []float64{}, []uint64{})
+				return m
+			},
+			want: prompb.MetricMetadata_HISTOGRAM,
+		},
+		{
+			name: "cumulative exponential histogram",
+			metric: func() pmetric.Metric {
+				metric := pmetric.NewMetric()
+				h := metric.SetEmptyExponentialHistogram()
+				h.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
+				return metric
+			},
+			want: prompb.MetricMetadata_HISTOGRAM,
+		},
+		{
+			name: "summary with start time",
+			metric: func() pmetric.Metric {
+				metric := pmetric.NewMetric()
+				metric.SetName("test_summary")
+				metric.SetEmptySummary()
+
+				dp := metric.Summary().DataPoints().AppendEmpty()
+				dp.SetTimestamp(pcommon.Timestamp(ts))
+				dp.SetStartTimestamp(pcommon.Timestamp(ts))
+
+				return metric
+			},
+			want: prompb.MetricMetadata_SUMMARY,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			metric := tt.metric()
+
+			metricType := otelMetricTypeToPromMetricType(metric)
+
+			assert.Equal(t, tt.want, metricType)
+		})
+	}
+}
+
+func TestOtelMetricsToMetadata(t *testing.T) {
+	ts := uint64(time.Now().UnixNano())
+	tests := []struct {
+		name    string
+		metrics pmetric.Metrics
+		want    []*prompb.MetricMetadata
+	}{
+		{
+			name:    "all types§",
+			metrics: GenerateMetricsAllTypesNoDataPointsHelpAndUnit(),
+			want: []*prompb.MetricMetadata{
+				{
+					Type: prompb.MetricMetadata_GAUGE,
+					MetricFamilyName: prometheustranslator.BuildCompliantName(getIntGaugeMetric(
+						testdata.TestGaugeDoubleMetricName,
+						pcommon.NewMap(),
+						1, ts,
+					), "", false),
+					Help: "gauge description",
+					Unit: "testing_unit",
+				},
+				{
+					Type: prompb.MetricMetadata_GAUGE,
+					MetricFamilyName: prometheustranslator.BuildCompliantName(getIntGaugeMetric(
+						testdata.TestGaugeIntMetricName,
+						pcommon.NewMap(),
+						1, ts,
+					), "", false),
+					Help: "gauge description",
+					Unit: "testing_unit",
+				},
+				{
+					Type: prompb.MetricMetadata_COUNTER,
+					MetricFamilyName: prometheustranslator.BuildCompliantName(getIntGaugeMetric(
+						testdata.TestSumDoubleMetricName,
+						pcommon.NewMap(),
+						1, ts,
+					), "", false),
+					Help: "sum description",
+					Unit: "testing_unit",
+				},
+				{
+					Type: prompb.MetricMetadata_COUNTER,
+					MetricFamilyName: prometheustranslator.BuildCompliantName(getIntGaugeMetric(
+						testdata.TestSumIntMetricName,
+						pcommon.NewMap(),
+						1, ts,
+					), "", false),
+					Help: "sum description",
+					Unit: "testing_unit",
+				},
+				{
+					Type: prompb.MetricMetadata_HISTOGRAM,
+					MetricFamilyName: prometheustranslator.BuildCompliantName(getIntGaugeMetric(
+						testdata.TestDoubleHistogramMetricName,
+						pcommon.NewMap(),
+						1, ts,
+					), "", false),
+					Help: "histogram description",
+					Unit: "testing_unit",
+				},
+				{
+					Type: prompb.MetricMetadata_SUMMARY,
+					MetricFamilyName: prometheustranslator.BuildCompliantName(getIntGaugeMetric(
+						testdata.TestDoubleSummaryMetricName,
+						pcommon.NewMap(),
+						1, ts,
+					), "", false),
+					Help: "summary description",
+					Unit: "testing_unit",
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			metaData := OtelMetricsToMetadata(tt.metrics, false)
+
+			for i := 0; i < len(metaData); i++ {
+				assert.Equal(t, tt.want[i].Type, metaData[i].Type)
+				assert.Equal(t, tt.want[i].MetricFamilyName, metaData[i].MetricFamilyName)
+				assert.Equal(t, tt.want[i].Help, metaData[i].Help)
+				assert.Equal(t, tt.want[i].Unit, metaData[i].Unit)
+			}
+
+		})
+	}
+}
+
+func GenerateMetricsAllTypesNoDataPointsHelpAndUnit() pmetric.Metrics {
+	md := testdata.GenerateMetricsOneEmptyInstrumentationLibrary()
+	ilm0 := md.ResourceMetrics().At(0).ScopeMetrics().At(0)
+	ms := ilm0.Metrics()
+	initMetric(ms.AppendEmpty(), testdata.TestGaugeDoubleMetricName, pmetric.MetricTypeGauge, "gauge description", "testing_unit")
+	initMetric(ms.AppendEmpty(), testdata.TestGaugeIntMetricName, pmetric.MetricTypeGauge, "gauge description", "testing_unit")
+	initMetric(ms.AppendEmpty(), testdata.TestSumDoubleMetricName, pmetric.MetricTypeSum, "sum description", "testing_unit")
+	initMetric(ms.AppendEmpty(), testdata.TestSumIntMetricName, pmetric.MetricTypeSum, "sum description", "testing_unit")
+	initMetric(ms.AppendEmpty(), testdata.TestDoubleHistogramMetricName, pmetric.MetricTypeHistogram, "histogram description", "testing_unit")
+	initMetric(ms.AppendEmpty(), testdata.TestDoubleSummaryMetricName, pmetric.MetricTypeSummary, "summary description", "testing_unit")
+	return md
+}
+
+func initMetric(m pmetric.Metric, name string, ty pmetric.MetricType, desc string, unit string) {
+	m.SetName(name)
+	m.SetDescription(desc)
+	m.SetUnit(unit)
+	//exhaustive:enforce
+	switch ty {
+	case pmetric.MetricTypeGauge:
+		m.SetEmptyGauge()
+
+	case pmetric.MetricTypeSum:
+		sum := m.SetEmptySum()
+		sum.SetIsMonotonic(true)
+		sum.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
+
+	case pmetric.MetricTypeHistogram:
+		histo := m.SetEmptyHistogram()
+		histo.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
+
+	case pmetric.MetricTypeExponentialHistogram:
+		m.SetEmptyExponentialHistogram()
+
+	case pmetric.MetricTypeSummary:
+		m.SetEmptySummary()
+	}
+}

From c3c4d022ff861aaa41cbb190185d832141c672fe Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Thu, 9 Nov 2023 15:55:29 +0100
Subject: [PATCH 11/20] chore: added changelog entry

---
 ...ote-write-add-option-to-send-metadata.yaml | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100755 .chloggen/prometheus-remote-write-add-option-to-send-metadata.yaml

diff --git a/.chloggen/prometheus-remote-write-add-option-to-send-metadata.yaml b/.chloggen/prometheus-remote-write-add-option-to-send-metadata.yaml
new file mode 100755
index 000000000000..45199deb9018
--- /dev/null
+++ b/.chloggen/prometheus-remote-write-add-option-to-send-metadata.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: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: exporter/prometheusremotewrite
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: prometheusremotewrite exporter add option to send metadata
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [ 13849 ]
+
+# (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: []

From 62588b8b4918cd61e1b994440801850a322fc7a0 Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Thu, 9 Nov 2023 16:00:13 +0100
Subject: [PATCH 12/20] chore: make linter happy

---
 .../otlp_to_openmetrics_metadata_test.go                      | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go
index fee41fbf6291..dde1ee31c4c2 100644
--- a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go
+++ b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go
@@ -124,7 +124,7 @@ func TestOtelMetricsToMetadata(t *testing.T) {
 						1, ts,
 					), "", false),
 					Help: "gauge description",
-					Unit: "testing_unit",
+					Unit: "testing_unit1",
 				},
 				{
 					Type: prompb.MetricMetadata_GAUGE,
@@ -198,7 +198,7 @@ func GenerateMetricsAllTypesNoDataPointsHelpAndUnit() pmetric.Metrics {
 	md := testdata.GenerateMetricsOneEmptyInstrumentationLibrary()
 	ilm0 := md.ResourceMetrics().At(0).ScopeMetrics().At(0)
 	ms := ilm0.Metrics()
-	initMetric(ms.AppendEmpty(), testdata.TestGaugeDoubleMetricName, pmetric.MetricTypeGauge, "gauge description", "testing_unit")
+	initMetric(ms.AppendEmpty(), testdata.TestGaugeDoubleMetricName, pmetric.MetricTypeGauge, "gauge description", "testing_unit1")
 	initMetric(ms.AppendEmpty(), testdata.TestGaugeIntMetricName, pmetric.MetricTypeGauge, "gauge description", "testing_unit")
 	initMetric(ms.AppendEmpty(), testdata.TestSumDoubleMetricName, pmetric.MetricTypeSum, "sum description", "testing_unit")
 	initMetric(ms.AppendEmpty(), testdata.TestSumIntMetricName, pmetric.MetricTypeSum, "sum description", "testing_unit")

From 41c68e7c446ebcb07a60a8bd0f789feca0cf5270 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juraj=20Mich=C3=A1lek?= <juraj.michalek132@gmail.com>
Date: Wed, 15 Nov 2023 18:49:04 +0100
Subject: [PATCH 13/20] Update exporter/prometheusremotewriteexporter/README.md

Co-authored-by: Antoine Toulme <antoine@toulme.name>
---
 exporter/prometheusremotewriteexporter/README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/exporter/prometheusremotewriteexporter/README.md b/exporter/prometheusremotewriteexporter/README.md
index f6dacf9da748..d230c2f9765c 100644
--- a/exporter/prometheusremotewriteexporter/README.md
+++ b/exporter/prometheusremotewriteexporter/README.md
@@ -52,7 +52,7 @@ The following settings can be optionally configured:
   - *Note the following headers cannot be changed: `Content-Encoding`, `Content-Type`, `X-Prometheus-Remote-Write-Version`, and `User-Agent`.*
 - `namespace`: prefix attached to each exported metric name.
 - `add_metric_suffixes`: If set to false, type and unit suffixes will not be added to metrics. Default: true.
-- `send_metadata`: If set to true, prometheus metadata will generated and sent. Default: false.
+- `send_metadata`: If set to true, prometheus metadata will be generated and sent. Default: false.
 - `remote_write_queue`: fine tuning for queueing and sending of the outgoing remote writes.
   - `enabled`: enable the sending queue (default: `true`)
   - `queue_size`: number of OTLP metrics that can be queued. Ignored if `enabled` is `false` (default: `10000`)

From ec03854a064e4b6358d3cc125f8eb3f0b8a2d1f7 Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Wed, 15 Nov 2023 18:51:41 +0100
Subject: [PATCH 14/20] chore: update comment copied comment

---
 exporter/prometheusremotewriteexporter/config.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/exporter/prometheusremotewriteexporter/config.go b/exporter/prometheusremotewriteexporter/config.go
index 2ceeffcae326..1f854918d2d5 100644
--- a/exporter/prometheusremotewriteexporter/config.go
+++ b/exporter/prometheusremotewriteexporter/config.go
@@ -49,7 +49,7 @@ type Config struct {
 	// AddMetricSuffixes controls whether unit and type suffixes are added to metrics on export
 	AddMetricSuffixes bool `mapstructure:"add_metric_suffixes"`
 
-	// AddMetricSuffixes controls whether unit and type suffixes are added to metrics on export
+	// SendMetadata controls whether prometheus metadata will be generated and sent
 	SendMetadata bool `mapstructure:"send_metadata"`
 }
 

From 7ae3f820296e73d22bee897cc8b32291cdacf134 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juraj=20Mich=C3=A1lek?= <juraj.michalek132@gmail.com>
Date: Sun, 19 Nov 2023 17:36:56 +0100
Subject: [PATCH 15/20] Update
 exporter/prometheusremotewriteexporter/exporter.go

Co-authored-by: Anthony Mirabella <a9@aneurysm9.com>
---
 exporter/prometheusremotewriteexporter/exporter.go | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/exporter/prometheusremotewriteexporter/exporter.go b/exporter/prometheusremotewriteexporter/exporter.go
index eef1a3c6de92..c9c849bcf5c7 100644
--- a/exporter/prometheusremotewriteexporter/exporter.go
+++ b/exporter/prometheusremotewriteexporter/exporter.go
@@ -137,10 +137,9 @@ func (prwe *prwExporter) PushMetrics(ctx context.Context, md pmetric.Metrics) er
 			err = consumererror.NewPermanent(err)
 		}
 
+		var m []*prompb.MetricMetadata
 		if prwe.exporterSettings.SendMetadata {
-			m := prometheusremotewrite.OtelMetricsToMetadata(md, prwe.exporterSettings.AddMetricSuffixes)
-			// Call export even if a conversion error, since there may be points that were successfully converted.
-			return multierr.Combine(err, prwe.handleExport(ctx, tsMap, m))
+			m = prometheusremotewrite.OtelMetricsToMetadata(md, prwe.exporterSettings.AddMetricSuffixes)
 		}
 		// Call export even if a conversion error, since there may be points that were successfully converted.
 		return multierr.Combine(err, prwe.handleExport(ctx, tsMap, nil))

From c47cea6cd3ebda56433573072287ec8e910d842a Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Sun, 19 Nov 2023 17:52:13 +0100
Subject: [PATCH 16/20] chore: add separate method for creating metadata
 requests

---
 .../prometheusremotewriteexporter/helper.go   | 38 ++++++-------------
 1 file changed, 11 insertions(+), 27 deletions(-)

diff --git a/exporter/prometheusremotewriteexporter/helper.go b/exporter/prometheusremotewriteexporter/helper.go
index c7187bf004d3..d5eca3086a7e 100644
--- a/exporter/prometheusremotewriteexporter/helper.go
+++ b/exporter/prometheusremotewriteexporter/helper.go
@@ -25,7 +25,7 @@ func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int,
 		sizeOfSeries := v.Size()
 
 		if sizeOfCurrentBatch+sizeOfSeries >= maxBatchByteSize {
-			wrapped := convertTimeseriesToRequest(tsArray, nil)
+			wrapped := convertTimeseriesToRequest(tsArray)
 			requests = append(requests, wrapped)
 
 			tsArray = make([]prompb.TimeSeries, 0, len(tsMap)-i)
@@ -38,7 +38,7 @@ func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int,
 	}
 
 	if len(tsArray) != 0 {
-		wrapped := convertTimeseriesToRequest(tsArray, nil)
+		wrapped := convertTimeseriesToRequest(tsArray)
 		requests = append(requests, wrapped)
 	}
 
@@ -49,7 +49,7 @@ func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int,
 		sizeOfM := v.Size()
 
 		if sizeOfCurrentBatch+sizeOfM >= maxBatchByteSize {
-			wrapped := convertTimeseriesToRequest(nil, mArray)
+			wrapped := convertMetadataToRequest(mArray)
 			requests = append(requests, wrapped)
 
 			mArray = make([]prompb.MetricMetadata, 0, len(m)-i)
@@ -62,38 +62,16 @@ func batchTimeSeries(tsMap map[string]*prompb.TimeSeries, maxBatchByteSize int,
 	}
 
 	if len(mArray) != 0 {
-		wrapped := convertTimeseriesToRequest(nil, mArray)
+		wrapped := convertMetadataToRequest(mArray)
 		requests = append(requests, wrapped)
 	}
 
 	return requests, nil
 }
 
-func convertTimeseriesToRequest(tsArray []prompb.TimeSeries, m []prompb.MetricMetadata) *prompb.WriteRequest {
+func convertTimeseriesToRequest(tsArray []prompb.TimeSeries) *prompb.WriteRequest {
 	// the remote_write endpoint only requires the timeseries.
 	// otlp defines it's own way to handle metric metadata
-
-	if m != nil && tsArray != nil {
-		return &prompb.WriteRequest{
-			// Prometheus requires time series to be sorted by Timestamp to avoid out of order problems.
-			// See:
-			// * https://github.com/open-telemetry/wg-prometheus/issues/10
-			// * https://github.com/open-telemetry/opentelemetry-collector/issues/2315
-			Timeseries: orderBySampleTimestamp(tsArray),
-			Metadata:   m,
-		}
-	}
-
-	if m != nil {
-		return &prompb.WriteRequest{
-			// Prometheus requires time series to be sorted by Timestamp to avoid out of order problems.
-			// See:
-			// * https://github.com/open-telemetry/wg-prometheus/issues/10
-			// * https://github.com/open-telemetry/opentelemetry-collector/issues/2315
-			Metadata: m,
-		}
-	}
-
 	return &prompb.WriteRequest{
 		// Prometheus requires time series to be sorted by Timestamp to avoid out of order problems.
 		// See:
@@ -103,6 +81,12 @@ func convertTimeseriesToRequest(tsArray []prompb.TimeSeries, m []prompb.MetricMe
 	}
 }
 
+func convertMetadataToRequest(m []prompb.MetricMetadata) *prompb.WriteRequest {
+	return &prompb.WriteRequest{
+		Metadata: m,
+	}
+}
+
 func orderBySampleTimestamp(tsArray []prompb.TimeSeries) []prompb.TimeSeries {
 	for i := range tsArray {
 		sL := tsArray[i].Samples

From a05570c4be69220660742bed6c06c536b30d2fe1 Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Sun, 19 Nov 2023 22:03:20 +0100
Subject: [PATCH 17/20] chore: fix metadata length calculation

---
 .../prometheusremotewrite/otlp_to_openmetrics_metadata.go   | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
index 995465da47f0..558685ca2918 100644
--- a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
+++ b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
@@ -35,8 +35,12 @@ func OtelMetricsToMetadata(md pmetric.Metrics, addMetricSuffixes bool) []*prompb
 
 	metadataLength := 0
 	for i := 0; i < resourceMetricsSlice.Len(); i++ {
-		metadataLength += resourceMetricsSlice.At(i).ScopeMetrics().Len()
+		scopeMetricsSlice := resourceMetricsSlice.At(i).ScopeMetrics()
+		for j := 0; j < scopeMetricsSlice.Len(); j++ {
+			metadataLength += scopeMetricsSlice.At(j).Metrics().Len()
+		}
 	}
+
 	var metadata = make([]*prompb.MetricMetadata, 0, metadataLength)
 	for i := 0; i < resourceMetricsSlice.Len(); i++ {
 		resourceMetrics := resourceMetricsSlice.At(i)

From 90c79d7720901b5dd292d89ec5eb68d50db3ec85 Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Sun, 19 Nov 2023 22:10:41 +0100
Subject: [PATCH 18/20] chore: fix pass metadata requests

---
 exporter/prometheusremotewriteexporter/exporter.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/exporter/prometheusremotewriteexporter/exporter.go b/exporter/prometheusremotewriteexporter/exporter.go
index c9c849bcf5c7..cc7a65f294b1 100644
--- a/exporter/prometheusremotewriteexporter/exporter.go
+++ b/exporter/prometheusremotewriteexporter/exporter.go
@@ -142,7 +142,7 @@ func (prwe *prwExporter) PushMetrics(ctx context.Context, md pmetric.Metrics) er
 			m = prometheusremotewrite.OtelMetricsToMetadata(md, prwe.exporterSettings.AddMetricSuffixes)
 		}
 		// Call export even if a conversion error, since there may be points that were successfully converted.
-		return multierr.Combine(err, prwe.handleExport(ctx, tsMap, nil))
+		return multierr.Combine(err, prwe.handleExport(ctx, tsMap, m))
 	}
 }
 

From 9f7f769fd11c3bf3f7ef5cbf492ca11e366c42b9 Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Sun, 19 Nov 2023 22:18:40 +0100
Subject: [PATCH 19/20] chore: update call of a function

---
 exporter/prometheusremotewriteexporter/helper_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/exporter/prometheusremotewriteexporter/helper_test.go b/exporter/prometheusremotewriteexporter/helper_test.go
index 1b838ec0a46b..8404bb6c9e9e 100644
--- a/exporter/prometheusremotewriteexporter/helper_test.go
+++ b/exporter/prometheusremotewriteexporter/helper_test.go
@@ -116,7 +116,7 @@ func TestEnsureTimeseriesPointsAreSortedByTimestamp(t *testing.T) {
 			},
 		},
 	}
-	got := convertTimeseriesToRequest(outOfOrder, nil)
+	got := convertTimeseriesToRequest(outOfOrder)
 
 	// We must ensure that the resulting Timeseries' sample points are sorted by Timestamp.
 	want := &prompb.WriteRequest{

From cfaa046602222d1fb5493a404316a2feeb6f7fa0 Mon Sep 17 00:00:00 2001
From: Juraj Michalek <juraj.michalek@matillion.com>
Date: Mon, 20 Nov 2023 20:46:56 +0100
Subject: [PATCH 20/20] chore: don't set unit in metadata for now

---
 .../otlp_to_openmetrics_metadata.go           |  1 -
 .../otlp_to_openmetrics_metadata_test.go      | 26 +++++++------------
 2 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
index 558685ca2918..b2564a3d187f 100644
--- a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
+++ b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go
@@ -54,7 +54,6 @@ func OtelMetricsToMetadata(md pmetric.Metrics, addMetricSuffixes bool) []*prompb
 					Type:             otelMetricTypeToPromMetricType(metric),
 					MetricFamilyName: prometheustranslator.BuildCompliantName(metric, "", addMetricSuffixes),
 					Help:             metric.Description(),
-					Unit:             metric.Unit(),
 				}
 				metadata = append(metadata, &entry)
 			}
diff --git a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go
index dde1ee31c4c2..6807ed7319d1 100644
--- a/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go
+++ b/pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go
@@ -114,7 +114,7 @@ func TestOtelMetricsToMetadata(t *testing.T) {
 	}{
 		{
 			name:    "all types§",
-			metrics: GenerateMetricsAllTypesNoDataPointsHelpAndUnit(),
+			metrics: GenerateMetricsAllTypesNoDataPointsHelp(),
 			want: []*prompb.MetricMetadata{
 				{
 					Type: prompb.MetricMetadata_GAUGE,
@@ -124,7 +124,6 @@ func TestOtelMetricsToMetadata(t *testing.T) {
 						1, ts,
 					), "", false),
 					Help: "gauge description",
-					Unit: "testing_unit1",
 				},
 				{
 					Type: prompb.MetricMetadata_GAUGE,
@@ -134,7 +133,6 @@ func TestOtelMetricsToMetadata(t *testing.T) {
 						1, ts,
 					), "", false),
 					Help: "gauge description",
-					Unit: "testing_unit",
 				},
 				{
 					Type: prompb.MetricMetadata_COUNTER,
@@ -144,7 +142,6 @@ func TestOtelMetricsToMetadata(t *testing.T) {
 						1, ts,
 					), "", false),
 					Help: "sum description",
-					Unit: "testing_unit",
 				},
 				{
 					Type: prompb.MetricMetadata_COUNTER,
@@ -154,7 +151,6 @@ func TestOtelMetricsToMetadata(t *testing.T) {
 						1, ts,
 					), "", false),
 					Help: "sum description",
-					Unit: "testing_unit",
 				},
 				{
 					Type: prompb.MetricMetadata_HISTOGRAM,
@@ -164,7 +160,6 @@ func TestOtelMetricsToMetadata(t *testing.T) {
 						1, ts,
 					), "", false),
 					Help: "histogram description",
-					Unit: "testing_unit",
 				},
 				{
 					Type: prompb.MetricMetadata_SUMMARY,
@@ -174,7 +169,6 @@ func TestOtelMetricsToMetadata(t *testing.T) {
 						1, ts,
 					), "", false),
 					Help: "summary description",
-					Unit: "testing_unit",
 				},
 			},
 		},
@@ -187,30 +181,28 @@ func TestOtelMetricsToMetadata(t *testing.T) {
 				assert.Equal(t, tt.want[i].Type, metaData[i].Type)
 				assert.Equal(t, tt.want[i].MetricFamilyName, metaData[i].MetricFamilyName)
 				assert.Equal(t, tt.want[i].Help, metaData[i].Help)
-				assert.Equal(t, tt.want[i].Unit, metaData[i].Unit)
 			}
 
 		})
 	}
 }
 
-func GenerateMetricsAllTypesNoDataPointsHelpAndUnit() pmetric.Metrics {
+func GenerateMetricsAllTypesNoDataPointsHelp() pmetric.Metrics {
 	md := testdata.GenerateMetricsOneEmptyInstrumentationLibrary()
 	ilm0 := md.ResourceMetrics().At(0).ScopeMetrics().At(0)
 	ms := ilm0.Metrics()
-	initMetric(ms.AppendEmpty(), testdata.TestGaugeDoubleMetricName, pmetric.MetricTypeGauge, "gauge description", "testing_unit1")
-	initMetric(ms.AppendEmpty(), testdata.TestGaugeIntMetricName, pmetric.MetricTypeGauge, "gauge description", "testing_unit")
-	initMetric(ms.AppendEmpty(), testdata.TestSumDoubleMetricName, pmetric.MetricTypeSum, "sum description", "testing_unit")
-	initMetric(ms.AppendEmpty(), testdata.TestSumIntMetricName, pmetric.MetricTypeSum, "sum description", "testing_unit")
-	initMetric(ms.AppendEmpty(), testdata.TestDoubleHistogramMetricName, pmetric.MetricTypeHistogram, "histogram description", "testing_unit")
-	initMetric(ms.AppendEmpty(), testdata.TestDoubleSummaryMetricName, pmetric.MetricTypeSummary, "summary description", "testing_unit")
+	initMetric(ms.AppendEmpty(), testdata.TestGaugeDoubleMetricName, pmetric.MetricTypeGauge, "gauge description")
+	initMetric(ms.AppendEmpty(), testdata.TestGaugeIntMetricName, pmetric.MetricTypeGauge, "gauge description")
+	initMetric(ms.AppendEmpty(), testdata.TestSumDoubleMetricName, pmetric.MetricTypeSum, "sum description")
+	initMetric(ms.AppendEmpty(), testdata.TestSumIntMetricName, pmetric.MetricTypeSum, "sum description")
+	initMetric(ms.AppendEmpty(), testdata.TestDoubleHistogramMetricName, pmetric.MetricTypeHistogram, "histogram description")
+	initMetric(ms.AppendEmpty(), testdata.TestDoubleSummaryMetricName, pmetric.MetricTypeSummary, "summary description")
 	return md
 }
 
-func initMetric(m pmetric.Metric, name string, ty pmetric.MetricType, desc string, unit string) {
+func initMetric(m pmetric.Metric, name string, ty pmetric.MetricType, desc string) {
 	m.SetName(name)
 	m.SetDescription(desc)
-	m.SetUnit(unit)
 	//exhaustive:enforce
 	switch ty {
 	case pmetric.MetricTypeGauge: