Preserve unknown, info, and stateset metric types from prometheus rec…

…eivers to exporters (open-telemetry#32605)

.chloggen/prometheus-additional-types.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: prometheusreceiver
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Prometheus receivers and exporters now preserve 'unknown', 'info', and 'stateset' types.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [16768]
+
+# (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: It uses the metric.metadata field with the 'prometheus.type' key to store the original type.
+
+# 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: []

exporter/prometheusexporter/collector.go

@@ -147,7 +147,12 @@ func (c *collector) convertGauge(metric pmetric.Metric, resourceAttrs pcommon.Ma
  case pmetric.NumberDataPointValueTypeDouble:
  value = ip.DoubleValue()
  }
- m, err := prometheus.NewConstMetric(desc, prometheus.GaugeValue, value, attributes...)
+ metricType := prometheus.GaugeValue
+ originalType, ok := metric.Metadata().Get(prometheustranslator.MetricMetadataTypeKey)
+ if ok && originalType.Str() == string(model.MetricTypeUnknown) {
+ metricType = prometheus.UntypedValue
+ }
+ m, err := prometheus.NewConstMetric(desc, metricType, value, attributes...)
  if err != nil {
  return nil, err
  }

exporter/prometheusexporter/collector_test.go

@@ -17,6 +17,8 @@ import (
  conventions "go.opentelemetry.io/collector/semconv/v1.6.1"
  "go.uber.org/zap"
  "go.uber.org/zap/zapcore"
+
+ prometheustranslator "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus"
 )
 
 type mockAccumulator struct {
@@ -396,6 +398,24 @@ func TestCollectMetrics(t *testing.T) {
  dp.Attributes().PutStr("label_2", "2")
  dp.SetTimestamp(pcommon.NewTimestampFromTime(ts))
 
+ return
+ },
+ },
+ {
+ name: "Unknown",
+ metricType: prometheus.UntypedValue,
+ value: 42.42,
+ metric: func(ts time.Time) (metric pmetric.Metric) {
+ metric = pmetric.NewMetric()
+ metric.SetName("test_metric")
+ metric.SetDescription("test description")
+ metric.Metadata().PutStr(prometheustranslator.MetricMetadataTypeKey, "unknown")
+ dp := metric.SetEmptyGauge().DataPoints().AppendEmpty()
+ dp.SetDoubleValue(42.42)
+ dp.Attributes().PutStr("label_1", "1")
+ dp.Attributes().PutStr("label_2", "2")
+ dp.SetTimestamp(pcommon.NewTimestampFromTime(ts))
+
  return
  },
  },

pkg/translator/prometheus/constants.go

@@ -0,0 +1,11 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package prometheus // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus"
+
+const (
+ // MetricMetadataTypeKey is the key used to store the original Prometheus
+ // type in metric metadata:
+ // https://github.com/open-telemetry/opentelemetry-specification/blob/e6eccba97ebaffbbfad6d4358408a2cead0ec2df/specification/compatibility/prometheus_and_openmetrics.md#metric-metadata
+ MetricMetadataTypeKey = "prometheus.type"
+)

pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata.go

@@ -4,22 +4,34 @@
 package prometheusremotewrite // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheusremotewrite"
 
 import (
+ "github.com/prometheus/common/model"
  "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 {
+ // metric metadata can be used to support Prometheus types that don't exist
+ // in OpenTelemetry.
+ typeFromMetadata, hasTypeFromMetadata := otelMetric.Metadata().Get(prometheustranslator.MetricMetadataTypeKey)
  switch otelMetric.Type() {
  case pmetric.MetricTypeGauge:
+ if hasTypeFromMetadata && typeFromMetadata.Str() == string(model.MetricTypeUnknown) {
+ return prompb.MetricMetadata_UNKNOWN
+ }
  return prompb.MetricMetadata_GAUGE
  case pmetric.MetricTypeSum:
- metricType := prompb.MetricMetadata_GAUGE
  if otelMetric.Sum().IsMonotonic() {
- metricType = prompb.MetricMetadata_COUNTER
+ return prompb.MetricMetadata_COUNTER
+ }
+ if hasTypeFromMetadata && typeFromMetadata.Str() == string(model.MetricTypeInfo) {
+ return prompb.MetricMetadata_INFO
  }
- return metricType
+ if hasTypeFromMetadata && typeFromMetadata.Str() == string(model.MetricTypeStateset) {
+ return prompb.MetricMetadata_STATESET
+ }
+ return prompb.MetricMetadata_GAUGE
  case pmetric.MetricTypeHistogram:
  return prompb.MetricMetadata_HISTOGRAM
  case pmetric.MetricTypeSummary:

pkg/translator/prometheusremotewrite/otlp_to_openmetrics_metadata_test.go

@@ -93,6 +93,50 @@ func TestOtelMetricTypeToPromMetricType(t *testing.T) {
  },
  want: prompb.MetricMetadata_SUMMARY,
  },
+ {
+ name: "unknown from metadata",
+ metric: func() pmetric.Metric {
+ metric := pmetric.NewMetric()
+ metric.SetName("test_sum")
+ metric.Metadata().PutStr(prometheustranslator.MetricMetadataTypeKey, "unknown")
+
+ dp := metric.SetEmptyGauge().DataPoints().AppendEmpty()
+ dp.SetDoubleValue(1)
+
+ return metric
+ },
+ want: prompb.MetricMetadata_UNKNOWN,
+ },
+ {
+ name: "info from metadata",
+ metric: func() pmetric.Metric {
+ metric := pmetric.NewMetric()
+ metric.SetName("test_sum")
+ metric.Metadata().PutStr(prometheustranslator.MetricMetadataTypeKey, "info")
+ metric.SetEmptySum().SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
+ metric.SetEmptySum().SetIsMonotonic(false)
+ dp := metric.Sum().DataPoints().AppendEmpty()
+ dp.SetDoubleValue(1)
+
+ return metric
+ },
+ want: prompb.MetricMetadata_INFO,
+ },
+ {
+ name: "stateset from metadata",
+ metric: func() pmetric.Metric {
+ metric := pmetric.NewMetric()
+ metric.SetName("test_sum")
+ metric.Metadata().PutStr(prometheustranslator.MetricMetadataTypeKey, "stateset")
+ metric.SetEmptySum().SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
+ metric.SetEmptySum().SetIsMonotonic(false)
+ dp := metric.Sum().DataPoints().AppendEmpty()
+ dp.SetDoubleValue(1)
+
+ return metric
+ },
+ want: prompb.MetricMetadata_STATESET,
+ },
  }
  for _, tt := range tests {
  t.Run(tt.name, func(t *testing.T) {

receiver/prometheusreceiver/internal/metricfamily.go

@@ -471,6 +471,7 @@ func (mf *metricFamily) appendMetric(metrics pmetric.MetricSlice, trimSuffixes b
  metric.SetName(name)
  metric.SetDescription(mf.metadata.Help)
  metric.SetUnit(prometheus.UnitWordToUCUM(mf.metadata.Unit))
+ metric.Metadata().PutStr(prometheus.MetricMetadataTypeKey, string(mf.metadata.Type))
 
  var pointCount int
 

receiver/prometheusreceiver/internal/metricsutil_test.go

@@ -65,6 +65,7 @@ func histogramPointNoValue(attributes []*kv, startTimestamp, timestamp pcommon.T
 func histogramMetric(name string, points ...pmetric.HistogramDataPoint) pmetric.Metric {
  metric := pmetric.NewMetric()
  metric.SetName(name)
+ metric.Metadata().PutStr("prometheus.type", "histogram")
  histogram := metric.SetEmptyHistogram()
  histogram.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
 
@@ -81,6 +82,7 @@ func histogramMetric(name string, points ...pmetric.HistogramDataPoint) pmetric.
 func exponentialHistogramMetric(name string, points ...pmetric.ExponentialHistogramDataPoint) pmetric.Metric {
  metric := pmetric.NewMetric()
  metric.SetName(name)
+ metric.Metadata().PutStr("prometheus.type", "histogram")
  histogram := metric.SetEmptyExponentialHistogram()
  histogram.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
 
@@ -198,6 +200,7 @@ func doublePointNoValue(attributes []*kv, startTimestamp, timestamp pcommon.Time
 func gaugeMetric(name string, points ...pmetric.NumberDataPoint) pmetric.Metric {
  metric := pmetric.NewMetric()
  metric.SetName(name)
+ metric.Metadata().PutStr("prometheus.type", "gauge")
  destPointL := metric.SetEmptyGauge().DataPoints()
  for _, point := range points {
  destPoint := destPointL.AppendEmpty()
@@ -210,6 +213,7 @@ func gaugeMetric(name string, points ...pmetric.NumberDataPoint) pmetric.Metric
 func sumMetric(name string, points ...pmetric.NumberDataPoint) pmetric.Metric {
  metric := pmetric.NewMetric()
  metric.SetName(name)
+ metric.Metadata().PutStr("prometheus.type", "counter")
  sum := metric.SetEmptySum()
  sum.SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
  sum.SetIsMonotonic(true)
@@ -260,6 +264,7 @@ func summaryPointNoValue(attributes []*kv, startTimestamp, timestamp pcommon.Tim
 func summaryMetric(name string, points ...pmetric.SummaryDataPoint) pmetric.Metric {
  metric := pmetric.NewMetric()
  metric.SetName(name)
+ metric.Metadata().PutStr("prometheus.type", "summary")
  destPointL := metric.SetEmptySummary().DataPoints()
  for _, point := range points {
  destPoint := destPointL.AppendEmpty()