Add otel type label for non-monotonic counters in OTLP endpoint

Signed-off-by: Carrie Edwards <edwrdscarrie@gmail.com>

docs/feature_flags.md

@@ -241,7 +241,7 @@ Examples of equivalent durations:
 
 When enabled, allows for the native ingestion of delta OTLP metrics, storing the raw sample values without conversion. This cannot be enabled in conjunction with `otlp-deltatocumulative`. It is recommended to enable `type-and-unit-labels`.
 
-Currently, the StartTimeUnixNano field is ignored. Delta metrics are given a `__temporality__` label with a value of "delta", and a `__type__` label with a value of "gauge"/"gaugehistogram" if `type-and-unit-labels` is enabled. OTel sum metrics are additionally given a `__monotonicity__` label with a value of "true"/"false".
+Currently, the StartTimeUnixNano field is ignored. Delta metrics are given a `__temporality__` label with a value of "delta", and a `__type__` label with a value of "gauge"/"gaugehistogram" if `type-and-unit-labels` is enabled. OTel sum metrics are additionally given a `__monotonicity__` label with a value of "true"/"false". OTel non-monotonic sum metrics are also given a `__otel_type__` label with a value of "sum".
 
 Delta support is in a very early stage of development and the ingestion and querying process my change over time. For the open proposal see [prometheus/proposals#48](https://github.com/prometheus/proposals/pull/48).
 

schema/labels.go

@@ -21,7 +21,7 @@ import (
 
 const (
 	// Special label names and selectors for schema.Metadata fields.
-	// They are currently private to ensure __name__, __type__, __unit__, __temporality__ and __monotonicity__ are used
+	// They are currently private to ensure __name__, __type__, __unit__, __temporality__,  __monotonicity__, and __otel_type__ are used
 	// together and remain extensible in Prometheus. See NewMetadataFromLabels and Metadata
 	// methods for the interactions with the labels package structs.
 	metricName         = "__name__"
@@ -29,12 +29,13 @@ const (
 	metricUnit         = "__unit__"
 	metricTemporality  = "__temporality__"
 	metricMonotonicity = "__monotonicity__"
+	metricOTelType     = "__otel_type__"
 )
 
 // IsMetadataLabel returns true if the given label name is a special
 // schema Metadata label.
 func IsMetadataLabel(name string) bool {
-	return name == metricName || name == metricType || name == metricUnit || name == metricTemporality || name == metricMonotonicity
+	return name == metricName || name == metricType || name == metricUnit || name == metricTemporality || name == metricMonotonicity || name == metricOTelType
 }
 
 // Metadata represents the core metric schema/metadata elements that:
@@ -82,6 +83,8 @@ type Metadata struct {
 	// Monotonicity represents whether the metric is monotonic. Empty string means monotonicity is not set.
 	// Valid values are "true" and "false".
 	Monotonicity string
+	// OTelType represents the original OTLP metric type for a metric ingested via the OTLP endpoint.
+	OTelType string
 }
 
 // NewMetadataFromLabels returns the schema metadata from the labels.
@@ -96,6 +99,7 @@ func NewMetadataFromLabels(ls labels.Labels) Metadata {
 		Unit:         ls.Get(metricUnit),
 		Temporality:  ls.Get(metricTemporality),
 		Monotonicity: ls.Get(metricMonotonicity),
+		OTelType:     ls.Get(metricOTelType),
 	}
 }
 
@@ -119,6 +123,8 @@ func (m Metadata) IsEmptyFor(labelName string) bool {
 		return m.Temporality == ""
 	case metricMonotonicity:
 		return m.Monotonicity == ""
+	case metricOTelType:
+		return m.OTelType == ""
 	default:
 		return true
 	}
@@ -142,6 +148,9 @@ func (m Metadata) AddToLabels(b *labels.ScratchBuilder) {
 	if m.Monotonicity != "" {
 		b.Add(metricMonotonicity, m.Monotonicity)
 	}
+	if m.OTelType != "" {
+		b.Add(metricOTelType, m.OTelType)
+	}
 }
 
 // SetToLabels injects metric schema metadata as labels into the labels.Builder.
@@ -159,6 +168,7 @@ func (m Metadata) SetToLabels(b *labels.Builder) {
 	b.Set(metricUnit, m.Unit)
 	b.Set(metricTemporality, m.Temporality)
 	b.Set(metricMonotonicity, m.Monotonicity)
+	b.Set(metricOTelType, m.OTelType)
 }
 
 // IgnoreOverriddenMetadataLabelsScratchBuilder is a wrapper over labels scratch builder

schema/labels_test.go

@@ -31,10 +31,11 @@ func TestMetadata(t *testing.T) {
 		Unit:         "seconds",
 		Temporality:  "delta",
 		Monotonicity: "true",
+		OTelType:     "sum",
 	}
 
 	for _, tcase := range []struct {
-		emptyName, emptyType, emptyUnit, emptyTemporality, emptyMonotonicity bool
+		emptyName, emptyType, emptyUnit, emptyTemporality, emptyMonotonicity, emptyOTelType bool
 	}{
 		{},
 		{emptyName: true},
@@ -42,6 +43,7 @@ func TestMetadata(t *testing.T) {
 		{emptyUnit: true},
 		{emptyTemporality: true},
 		{emptyMonotonicity: true},
+		{emptyOTelType: true},
 		{emptyName: true, emptyType: true, emptyUnit: true, emptyTemporality: true},
 	} {
 		var (
@@ -75,6 +77,10 @@ func TestMetadata(t *testing.T) {
 				lb.Add(metricMonotonicity, testMeta.Monotonicity)
 				expectedMeta.Monotonicity = testMeta.Monotonicity
 			}
+			if !tcase.emptyOTelType {
+				lb.Add(metricOTelType, testMeta.OTelType)
+				expectedMeta.OTelType = testMeta.OTelType
+			}
 			lb.Sort()
 			expectedLabels = lb.Labels()
 		}
@@ -93,6 +99,7 @@ func TestMetadata(t *testing.T) {
 				require.Equal(t, tcase.emptyUnit, expectedMeta.IsEmptyFor(metricUnit))
 				require.Equal(t, tcase.emptyTemporality, expectedMeta.IsEmptyFor(metricTemporality))
 				require.Equal(t, tcase.emptyMonotonicity, expectedMeta.IsEmptyFor(metricMonotonicity))
+				require.Equal(t, tcase.emptyOTelType, expectedMeta.IsEmptyFor(metricOTelType))
 			}
 			{
 				// From Metadata to labels for various builders.
@@ -129,8 +136,9 @@ func TestIgnoreOverriddenMetadataLabelsScratchBuilder(t *testing.T) {
 				Unit:         "seconds",
 				Temporality:  "delta",
 				Monotonicity: "true",
+				OTelType:     "sum",
 			},
-			expectedLabels: labels.FromStrings(metricName, "metric_total", metricType, string(model.MetricTypeCounter), metricUnit, "seconds", metricTemporality, "delta", metricMonotonicity, "true", "foo", "bar"),
+			expectedLabels: labels.FromStrings(metricName, "metric_total", metricType, string(model.MetricTypeCounter), metricUnit, "seconds", metricTemporality, "delta", metricMonotonicity, "true", metricOTelType, "sum", "foo", "bar"),
 		},
 		{
 			highPrioMeta: Metadata{
@@ -178,6 +186,7 @@ func TestIsMetadataLabel(t *testing.T) {
 		{"__unit__", true},
 		{"__temporality__", true},
 		{"__monotonicity__", true},
+		{"__otel_type__", true},
 		{"foo", false},
 		{"bar", false},
 		{"__other__", false},

storage/remote/otlptranslator/prometheusremotewrite/metrics_to_prw_test.go

@@ -683,13 +683,19 @@ func createPromFloatSeriesWithTemporality(name, temporality string, ts time.Time
 }
 
 func createPromFloatSeriesWithTemporalityAndMonotonicity(name, temporality, monotonicity string, ts time.Time) prompb.TimeSeries {
+	labels := []prompb.Label{
+		{Name: "__monotonicity__", Value: monotonicity},
+		{Name: "__name__", Value: name},
+		{Name: "__temporality__", Value: temporality},
+		{Name: "test_label", Value: "test_value"},
+	}
+
+	if monotonicity == "false" {
+		labels = append(labels, prompb.Label{Name: "__otel_type__", Value: "sum"})
+	}
+
 	return prompb.TimeSeries{
-		Labels: []prompb.Label{
-			{Name: "__monotonicity__", Value: monotonicity},
-			{Name: "__name__", Value: name},
-			{Name: "__temporality__", Value: temporality},
-			{Name: "test_label", Value: "test_value"},
-		},
+		Labels: labels,
 		Samples: []prompb.Sample{{
 			Value:     5,
 			Timestamp: ts.UnixMilli(),

storage/remote/otlptranslator/prometheusremotewrite/number_data_points.go

@@ -104,6 +104,7 @@ func (c *PrometheusConverter) addSumNumberDataPoints(ctx context.Context, dataPo
 				lbls = append(lbls, prompb.Label{Name: "__monotonicity__", Value: "true"})
 			} else {
 				lbls = append(lbls, prompb.Label{Name: "__monotonicity__", Value: "false"})
+				lbls = append(lbls, prompb.Label{Name: "__otel_type__", Value: "sum"})
 			}
 		}