feat: add support for MetricTypeSum (open-telemetry#37156)

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

Prometheus translation rw2 add support for MetricTypeSum.

The current work was inspired by
open-telemetry#36353

<!-- Issue number (e.g. open-telemetry#1234) or full URL to issue, if applicable. -->
#### Link to tracking issue open-telemetry#33661

Author: perebaj

.chloggen/add-metrictypesum-support.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: pkg/translator/prometheusremotewrite
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: add support for metric type sum in FromMetricsV2
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [33661]
+
+# (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: The public function is partially implemented and not ready for use
+
+# 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: [api]

pkg/translator/prometheusremotewrite/helper_test.go

@@ -13,6 +13,7 @@ import (
 	"github.com/prometheus/common/model"
 	"github.com/prometheus/prometheus/model/timestamp"
 	"github.com/prometheus/prometheus/prompb"
+	writev2 "github.com/prometheus/prometheus/prompb/io/prometheus/write/v2"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"go.opentelemetry.io/collector/pdata/pcommon"
@@ -545,6 +546,46 @@ func Test_getPromExemplars(t *testing.T) {
 	}
 }
 
+func Test_getPromExemplarsV2(t *testing.T) {
+	tnow := time.Now()
+	tests := []struct {
+		name      string
+		histogram pmetric.HistogramDataPoint
+		expected  []writev2.Exemplar
+	}{
+		{
+			name:      "with_exemplars_double_value",
+			histogram: getHistogramDataPointWithExemplars(t, tnow, floatVal1, traceIDValue1, spanIDValue1, label11, value11),
+			expected: []writev2.Exemplar{
+				{
+					Value:     floatVal1,
+					Timestamp: timestamp.FromTime(tnow),
+					// TODO: after deal with examplar labels on getPromExemplarsV2, add the labels here
+					// LabelsRefs: []uint32{},
+				},
+			},
+		},
+		{
+			name:      "with_exemplars_int_value",
+			histogram: getHistogramDataPointWithExemplars(t, tnow, intVal2, traceIDValue1, spanIDValue1, label11, value11),
+			expected: []writev2.Exemplar{
+				{
+					Value:     float64(intVal2),
+					Timestamp: timestamp.FromTime(tnow),
+					// TODO: after deal with examplar labels on getPromExemplarsV2, add the labels here
+					// LabelsRefs: []uint32{},
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			requests := getPromExemplarsV2(tt.histogram)
+			assert.Exactly(t, tt.expected, requests)
+		})
+	}
+}
+
 func TestAddResourceTargetInfo(t *testing.T) {
 	resourceAttrMap := map[string]any{
 		conventions.AttributeServiceName:       "service-name",

pkg/translator/prometheusremotewrite/metrics_to_prw_v2.go

@@ -6,6 +6,7 @@ package prometheusremotewrite // import "github.com/open-telemetry/opentelemetry
 import (
 	"errors"
 	"fmt"
+	"sort"
 	"strconv"
 
 	"github.com/prometheus/prometheus/prompb"
@@ -75,12 +76,19 @@ func (c *prometheusConverterV2) fromMetrics(md pmetric.Metrics, settings Setting
 				case pmetric.MetricTypeGauge:
 					dataPoints := metric.Gauge().DataPoints()
 					if dataPoints.Len() == 0 {
-						errs = multierr.Append(errs, fmt.Errorf("empty data points. %s is dropped", metric.Name()))
 						break
 					}
 					c.addGaugeNumberDataPoints(dataPoints, resource, settings, promName)
 				case pmetric.MetricTypeSum:
-					// TODO implement
+					dataPoints := metric.Sum().DataPoints()
+					if dataPoints.Len() == 0 {
+						break
+					}
+					if !metric.Sum().IsMonotonic() {
+						c.addGaugeNumberDataPoints(dataPoints, resource, settings, promName)
+					} else {
+						c.addSumNumberDataPoints(dataPoints, resource, metric, settings, promName)
+					}
 				case pmetric.MetricTypeHistogram:
 					// TODO implement
 				case pmetric.MetricTypeExponentialHistogram:
@@ -108,13 +116,14 @@ func (c *prometheusConverterV2) timeSeries() []writev2.TimeSeries {
 	return allTS
 }
 
-func (c *prometheusConverterV2) addSample(sample *writev2.Sample, lbls []prompb.Label) *writev2.TimeSeries {
-	if sample == nil || len(lbls) == 0 {
-		// This shouldn't happen
-		return nil
-	}
-
+func (c *prometheusConverterV2) addSample(sample *writev2.Sample, lbls []prompb.Label) {
 	buf := make([]uint32, 0, len(lbls)*2)
+
+	// TODO: Read the PRW spec to see if labels need to be sorted. If it is, then we need to sort in export code. If not, we can sort in the test. (@dashpole have more context on this)
+	sort.Slice(lbls, func(i, j int) bool {
+		return lbls[i].Name < lbls[j].Name
+	})
+
 	var off uint32
 	for _, l := range lbls {
 		off = c.symbolTable.Symbolize(l.Name)
@@ -127,6 +136,8 @@ func (c *prometheusConverterV2) addSample(sample *writev2.Sample, lbls []prompb.
 		Samples:    []writev2.Sample{*sample},
 	}
 	c.unique[timeSeriesSignature(lbls)] = &ts
+}
 
-	return &ts
+// TODO: implement this function.
+func (c *prometheusConverterV2) addTimeSeriesIfNeeded(_ []prompb.Label, _ pcommon.Timestamp, _ pcommon.Timestamp) {
 }

pkg/translator/prometheusremotewrite/metrics_to_prw_v2_test.go

@@ -32,9 +32,15 @@ func TestFromMetricsV2(t *testing.T) {
 					{Timestamp: convertTimeStamp(pcommon.Timestamp(ts)), Value: 1.23},
 				},
 			},
+			"1": {
+				LabelsRefs: []uint32{1, 9, 3, 4, 5, 6, 7, 8},
+				Samples: []writev2.Sample{
+					{Timestamp: convertTimeStamp(pcommon.Timestamp(ts)), Value: 1.23},
+				},
+			},
 		}
 	}
-	wantedSymbols := []string{"", "series_name_2", "value-2", "series_name_3", "value-3", "__name__", "gauge_1", "series_name_1", "value-1"}
+	wantedSymbols := []string{"", "series_name_2", "value-2", "series_name_3", "value-3", "__name__", "gauge_1", "series_name_1", "value-1", "sum_1"}
 	tsMap, symbolsTable, err := FromMetricsV2(payload.Metrics(), settings)
 	require.NoError(t, err)
 	require.Equal(t, want(), tsMap)

pkg/translator/prometheusremotewrite/number_data_points_v2.go

@@ -7,7 +7,9 @@ import (
 	"math"
 
 	"github.com/prometheus/common/model"
+	"github.com/prometheus/prometheus/model/timestamp"
 	"github.com/prometheus/prometheus/model/value"
+	"github.com/prometheus/prometheus/prompb"
 	writev2 "github.com/prometheus/prometheus/prompb/io/prometheus/write/v2"
 	"go.opentelemetry.io/collector/pdata/pcommon"
 	"go.opentelemetry.io/collector/pdata/pmetric"
@@ -45,3 +47,82 @@ func (c *prometheusConverterV2) addGaugeNumberDataPoints(dataPoints pmetric.Numb
 		c.addSample(sample, labels)
 	}
 }
+
+func (c *prometheusConverterV2) addSumNumberDataPoints(dataPoints pmetric.NumberDataPointSlice,
+	resource pcommon.Resource, metric pmetric.Metric, settings Settings, name string,
+) {
+	for x := 0; x < dataPoints.Len(); x++ {
+		pt := dataPoints.At(x)
+		lbls := createAttributes(
+			resource,
+			pt.Attributes(),
+			settings.ExternalLabels,
+			nil,
+			true,
+			model.MetricNameLabel,
+			name,
+		)
+
+		sample := &writev2.Sample{
+			// convert ns to ms
+			Timestamp: convertTimeStamp(pt.Timestamp()),
+		}
+		switch pt.ValueType() {
+		case pmetric.NumberDataPointValueTypeInt:
+			sample.Value = float64(pt.IntValue())
+		case pmetric.NumberDataPointValueTypeDouble:
+			sample.Value = pt.DoubleValue()
+		}
+		if pt.Flags().NoRecordedValue() {
+			sample.Value = math.Float64frombits(value.StaleNaN)
+		}
+		// TODO: properly add exemplars to the TimeSeries
+		c.addSample(sample, lbls)
+
+		if settings.ExportCreatedMetric && metric.Sum().IsMonotonic() {
+			startTimestamp := pt.StartTimestamp()
+			if startTimestamp != 0 {
+				return
+			}
+
+			createdLabels := make([]prompb.Label, len(lbls))
+			copy(createdLabels, lbls)
+			for i, l := range createdLabels {
+				if l.Name == model.MetricNameLabel {
+					createdLabels[i].Value = name + createdSuffix
+					break
+				}
+			}
+			// TODO: implement this function.
+			c.addTimeSeriesIfNeeded(createdLabels, startTimestamp, pt.Timestamp())
+		}
+	}
+}
+
+// getPromExemplarsV2 returns a slice of writev2.Exemplar from pdata exemplars.
+func getPromExemplarsV2[T exemplarType](pt T) []writev2.Exemplar {
+	promExemplars := make([]writev2.Exemplar, 0, pt.Exemplars().Len())
+	for i := 0; i < pt.Exemplars().Len(); i++ {
+		exemplar := pt.Exemplars().At(i)
+
+		var promExemplar writev2.Exemplar
+
+		switch exemplar.ValueType() {
+		case pmetric.ExemplarValueTypeInt:
+			promExemplar = writev2.Exemplar{
+				Value:     float64(exemplar.IntValue()),
+				Timestamp: timestamp.FromTime(exemplar.Timestamp().AsTime()),
+			}
+		case pmetric.ExemplarValueTypeDouble:
+			promExemplar = writev2.Exemplar{
+				Value:     exemplar.DoubleValue(),
+				Timestamp: timestamp.FromTime(exemplar.Timestamp().AsTime()),
+			}
+		}
+		// TODO append labels to promExemplar.Labels
+
+		promExemplars = append(promExemplars, promExemplar)
+	}
+
+	return promExemplars
+}