Use the prometheus.type metric metadata to support double-writing unknown-typed metrics

exporter/collector/googlemanagedprometheus/extra_metrics.go

@@ -17,26 +17,13 @@ package googlemanagedprometheus
 import (
 	"time"
 
-	"go.opentelemetry.io/collector/featuregate"
+	"github.com/prometheus/common/model"
 	"go.opentelemetry.io/collector/pdata/pcommon"
 	"go.opentelemetry.io/collector/pdata/pmetric"
 	semconv "go.opentelemetry.io/collector/semconv/v1.18.0"
 )
 
-const (
-	// Special attribute key used by Ops Agent prometheus receiver to denote untyped
-	// prometheus metric. Internal use only.
-	GCPOpsAgentUntypedMetricKey = "prometheus.googleapis.com/internal/untyped_metric"
-
-	gcpUntypedDoubleExportGateKey = "gcp.untypedDoubleExport"
-)
-
-var untypedDoubleExportFeatureGate = featuregate.GlobalRegistry().MustRegister(
-	gcpUntypedDoubleExportGateKey,
-	featuregate.StageAlpha,
-	featuregate.WithRegisterFromVersion("v0.77.0"),
-	featuregate.WithRegisterDescription("Enable automatically exporting untyped Prometheus metrics as both gauge and cumulative to GCP."),
-	featuregate.WithRegisterReferenceURL("https://github.com/GoogleCloudPlatform/opentelemetry-operations-go/pull/668"))
+const prometheusMetricMetadataTypeKey = "prometheus.type"
 
 func (c Config) ExtraMetrics(m pmetric.Metrics) {
 	addUntypedMetrics(m)
@@ -47,9 +34,6 @@ func (c Config) ExtraMetrics(m pmetric.Metrics) {
 // addUntypedMetrics looks for any Gauge data point with the special Ops Agent untyped metric
 // attribute and duplicates that data point to a matching Sum.
 func addUntypedMetrics(m pmetric.Metrics) {
-	if !untypedDoubleExportFeatureGate.IsEnabled() {
-		return
-	}
 	rms := m.ResourceMetrics()
 	for i := 0; i < rms.Len(); i++ {
 		rm := rms.At(i)
@@ -69,21 +53,21 @@ func addUntypedMetrics(m pmetric.Metrics) {
 					continue
 				}
 
+				if !isUnknown(metric) {
+					continue
+				}
+
 				// attribute is set on the data point
 				gauge := metric.Gauge()
 				points := gauge.DataPoints()
 				for l := 0; l < points.Len(); l++ {
-					point := points.At(l)
-					val, ok := point.Attributes().Get(GCPOpsAgentUntypedMetricKey)
-					if !(ok && val.AsString() == "true") {
-						continue
-					}
-
 					// Add the new Sum metric and copy values over from this Gauge
+					point := points.At(l)
 					newMetric := mes.AppendEmpty()
 					newMetric.SetName(metric.Name())
 					newMetric.SetDescription(metric.Description())
 					newMetric.SetUnit(metric.Unit())
+					newMetric.Metadata().PutStr(prometheusMetricMetadataTypeKey, string(model.MetricTypeUnknown))
 
 					newSum := newMetric.SetEmptySum()
 					newSum.SetIsMonotonic(true)
@@ -105,6 +89,11 @@ func addUntypedMetrics(m pmetric.Metrics) {
 	}
 }
 
+func isUnknown(metric pmetric.Metric) bool {
+	originalType, ok := metric.Metadata().Get(prometheusMetricMetadataTypeKey)
+	return ok && originalType.Str() == string(model.MetricTypeUnknown)
+}
+
 // resourceID identifies a resource. We only send one target info for each
 // resourceID.
 type resourceID struct {

exporter/collector/googlemanagedprometheus/extra_metrics_test.go

@@ -19,7 +19,6 @@ import (
 	"time"
 
 	"github.com/stretchr/testify/assert"
-	"go.opentelemetry.io/collector/featuregate"
 	"go.opentelemetry.io/collector/pdata/pcommon"
 	"go.opentelemetry.io/collector/pdata/pmetric"
 	semconv "go.opentelemetry.io/collector/semconv/v1.18.0"
@@ -53,11 +52,10 @@ func appendMetric(metrics pmetric.Metrics, timestamp time.Time) pmetric.Metrics
 func TestAddExtraMetrics(t *testing.T) {
 	timestamp := time.Now()
 	for _, tc := range []struct {
-		input                    pmetric.Metrics
-		expected                 pmetric.ResourceMetricsSlice
-		name                     string
-		config                   Config
-		enableUntypedFeatureGate bool
+		input    pmetric.Metrics
+		expected pmetric.ResourceMetricsSlice
+		name     string
+		config   Config
 	}{
 		{
 			name:   "add target info from resource metric",
@@ -322,49 +320,44 @@ func TestAddExtraMetrics(t *testing.T) {
 			}(),
 		},
 		{
-			name:                     "add untyped Sum metric from Gauge",
-			enableUntypedFeatureGate: true,
-			config:                   Config{},
+			name:   "add untyped Sum metric from Gauge",
+			config: Config{},
 			input: func() pmetric.Metrics {
 				metrics := testMetric(timestamp)
 				metrics.ResourceMetrics().At(0).
 					ScopeMetrics().At(0).
 					Metrics().At(0).
-					Gauge().DataPoints().At(0).
-					Attributes().PutStr(GCPOpsAgentUntypedMetricKey, "true")
+					Metadata().PutStr("prometheus.type", "unknown")
 				return metrics
 			}(),
 			expected: func() pmetric.ResourceMetricsSlice {
 				metrics := testMetric(timestamp).ResourceMetrics()
 
-				dataPoint := metrics.At(0).
+				metrics.At(0).
 					ScopeMetrics().At(0).
 					Metrics().At(0).
-					Gauge().DataPoints().At(0)
-				dataPoint.Attributes().PutStr(GCPOpsAgentUntypedMetricKey, "true")
+					Metadata().PutStr("prometheus.type", "unknown")
 
 				metric := metrics.At(0).ScopeMetrics().At(0).Metrics().AppendEmpty()
 				metric.SetName("baz-metric")
+				metric.Metadata().PutStr("prometheus.type", "unknown")
 				metric.SetEmptySum().DataPoints().AppendEmpty().SetIntValue(2112)
 				metric.Sum().SetIsMonotonic(true)
 				metric.Sum().SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
 				metric.Sum().DataPoints().At(0).SetTimestamp(pcommon.NewTimestampFromTime(timestamp))
-				metric.Sum().DataPoints().At(0).Attributes().PutStr(GCPOpsAgentUntypedMetricKey, "true")
 
 				return metrics
 			}(),
 		},
 		{
-			name:                     "add untyped Sum metric from Gauge (double value)",
-			enableUntypedFeatureGate: true,
-			config:                   Config{},
+			name:   "add untyped Sum metric from Gauge (double value)",
+			config: Config{},
 			input: func() pmetric.Metrics {
 				metrics := testMetric(timestamp)
 				metrics.ResourceMetrics().At(0).
 					ScopeMetrics().At(0).
 					Metrics().At(0).
-					Gauge().DataPoints().At(0).
-					Attributes().PutStr(GCPOpsAgentUntypedMetricKey, "true")
+					Metadata().PutStr("prometheus.type", "unknown")
 				metrics.ResourceMetrics().At(0).
 					ScopeMetrics().At(0).
 					Metrics().At(0).
@@ -375,100 +368,69 @@ func TestAddExtraMetrics(t *testing.T) {
 			expected: func() pmetric.ResourceMetricsSlice {
 				metrics := testMetric(timestamp).ResourceMetrics()
 
-				dataPoint := metrics.At(0).
+				metrics.At(0).ScopeMetrics().At(0).Metrics().At(0).Metadata().PutStr("prometheus.type", "unknown")
+				metrics.At(0).
 					ScopeMetrics().At(0).
 					Metrics().At(0).
-					Gauge().DataPoints().At(0)
-				dataPoint.Attributes().PutStr(GCPOpsAgentUntypedMetricKey, "true")
-				dataPoint.SetDoubleValue(123.5)
+					Gauge().DataPoints().At(0).SetDoubleValue(123.5)
 
 				metric := metrics.At(0).ScopeMetrics().At(0).Metrics().AppendEmpty()
 				metric.SetName("baz-metric")
+				metric.Metadata().PutStr("prometheus.type", "unknown")
 				metric.SetEmptySum().DataPoints().AppendEmpty().SetDoubleValue(123.5)
 				metric.Sum().SetIsMonotonic(true)
 				metric.Sum().SetAggregationTemporality(pmetric.AggregationTemporalityCumulative)
 				metric.Sum().DataPoints().At(0).SetTimestamp(pcommon.NewTimestampFromTime(timestamp))
-				metric.Sum().DataPoints().At(0).Attributes().PutStr(GCPOpsAgentUntypedMetricKey, "true")
 
 				return metrics
 			}(),
 		},
 		{
-			name:                     "untyped Gauge does nothing if feature gate is disabled",
-			enableUntypedFeatureGate: false,
-			config:                   Config{},
-			input: func() pmetric.Metrics {
-				metrics := testMetric(timestamp)
-				metrics.ResourceMetrics().At(0).
-					ScopeMetrics().At(0).
-					Metrics().At(0).
-					Gauge().DataPoints().At(0).
-					Attributes().PutStr(GCPOpsAgentUntypedMetricKey, "true")
-				return metrics
-			}(),
-			expected: func() pmetric.ResourceMetricsSlice {
-				metrics := testMetric(timestamp).ResourceMetrics()
-				dataPoint := metrics.At(0).
-					ScopeMetrics().At(0).
-					Metrics().At(0).
-					Gauge().DataPoints().At(0)
-				dataPoint.Attributes().PutStr(GCPOpsAgentUntypedMetricKey, "true")
-				return metrics
-			}(),
-		},
-		{
-			name:                     "untyped Gauge does nothing if feature gate is enabled and key!=true",
-			enableUntypedFeatureGate: true,
-			config:                   Config{},
+			name:   "untyped Gauge does nothing if feature gate is enabled and key!=unknown",
+			config: Config{},
 			input: func() pmetric.Metrics {
 				metrics := testMetric(timestamp)
 				metrics.ResourceMetrics().At(0).
 					ScopeMetrics().At(0).
 					Metrics().At(0).
-					Gauge().DataPoints().At(0).
-					Attributes().PutStr(GCPOpsAgentUntypedMetricKey, "foo")
+					Metadata().PutStr("prometheus.type", "foo")
 				return metrics
 			}(),
 			expected: func() pmetric.ResourceMetricsSlice {
 				metrics := testMetric(timestamp).ResourceMetrics()
-				dataPoint := metrics.At(0).
+				metrics.At(0).
 					ScopeMetrics().At(0).
 					Metrics().At(0).
-					Gauge().DataPoints().At(0)
-				dataPoint.Attributes().PutStr(GCPOpsAgentUntypedMetricKey, "foo")
+					Metadata().PutStr("prometheus.type", "foo")
 				return metrics
 			}(),
 		},
 		{
-			name:                     "untyped non-Gauge does nothing if feature gate is enabled",
-			enableUntypedFeatureGate: true,
-			config:                   Config{},
+			name:   "untyped non-Gauge does nothing if feature gate is enabled",
+			config: Config{},
 			input: func() pmetric.Metrics {
 				metrics := testMetric(timestamp)
-				metrics.ResourceMetrics().At(0).
+				metric := metrics.ResourceMetrics().At(0).
 					ScopeMetrics().At(0).
-					Metrics().AppendEmpty().SetEmptyHistogram().DataPoints().AppendEmpty().
-					Attributes().PutStr(GCPOpsAgentUntypedMetricKey, "true")
+					Metrics().AppendEmpty()
+
+				metric.SetEmptyHistogram().DataPoints().AppendEmpty()
+				metric.Metadata().PutStr("prometheus.type", "unknown")
 				return metrics
 			}(),
 			expected: func() pmetric.ResourceMetricsSlice {
 				metrics := testMetric(timestamp).ResourceMetrics()
-				metrics.At(0).
+				metric := metrics.At(0).
 					ScopeMetrics().At(0).
-					Metrics().AppendEmpty().SetEmptyHistogram().DataPoints().AppendEmpty().
-					Attributes().PutStr(GCPOpsAgentUntypedMetricKey, "true")
+					Metrics().AppendEmpty()
+
+				metric.SetEmptyHistogram().DataPoints().AppendEmpty()
+				metric.Metadata().PutStr("prometheus.type", "unknown")
 				return metrics
 			}(),
 		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
-			if tc.enableUntypedFeatureGate {
-				assert.NoError(t, featuregate.GlobalRegistry().Set(gcpUntypedDoubleExportGateKey, true))
-				// disable it after the test is over
-				defer func() {
-					assert.NoError(t, featuregate.GlobalRegistry().Set(gcpUntypedDoubleExportGateKey, false))
-				}()
-			}
 			m := tc.input
 			tc.config.ExtraMetrics(m)
 			assert.EqualValues(t, tc.expected, m.ResourceMetrics())

exporter/collector/googlemanagedprometheus/go.mod

@@ -6,6 +6,7 @@ toolchain go1.22.0
 
 require (
 	github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus v0.99.0
+	github.com/prometheus/common v0.53.0
 	github.com/stretchr/testify v1.9.0
 	go.opentelemetry.io/collector/featuregate v1.6.0
 	go.opentelemetry.io/collector/pdata v1.6.0
@@ -21,6 +22,7 @@ require (
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_model v0.6.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
 	golang.org/x/net v0.23.0 // indirect
 	golang.org/x/sys v0.18.0 // indirect

exporter/collector/googlemanagedprometheus/go.sum

@@ -27,6 +27,10 @@ github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometh
 github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus v0.99.0/go.mod h1:sQID67FDKapC9OJNgVxcG7MscZRpWIfgWrSodEZGedo=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/prometheus/client_model v0.6.0 h1:k1v3CzpSRUTrKMppY35TLwPvxHqBu0bYgxZzqGIgaos=
+github.com/prometheus/client_model v0.6.0/go.mod h1:NTQHnmxFpouOD0DpvP4XujX3CdOAGQPoaGhyTchlyt8=
+github.com/prometheus/common v0.53.0 h1:U2pL9w9nmJwJDa4qqLQ3ZaePJ6ZTwt7cMD3AG3+aLCE=
+github.com/prometheus/common v0.53.0/go.mod h1:BrxBKv3FWBIGXw89Mg1AeBq7FSyRzXWI3l3e7W3RN5U=
 github.com/rogpeppe/go-internal v1.10.0 h1:TMyTOH3F/DB16zRVcYyreMH6GnZZrwQVAoYjRBZyWFQ=
 github.com/rogpeppe/go-internal v1.10.0/go.mod h1:UQnix2H7Ngw/k4C5ijL5+65zddjncjaFoBhdsK/akog=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

exporter/collector/googlemanagedprometheus/naming.go

@@ -25,6 +25,7 @@ import (
 
 // GetMetricName returns the metric name with GMP-specific suffixes. The.
 func (c Config) GetMetricName(baseName string, metric pmetric.Metric) (string, error) {
+	unknown := isUnknown(metric)
 	// First, build a name that is compliant with prometheus conventions
 	compliantName := prometheus.BuildCompliantName(metric, "", c.AddMetricSuffixes)
 	// Second, ad the GMP-specific suffix
@@ -34,9 +35,9 @@ func (c Config) GetMetricName(baseName string, metric pmetric.Metric) (string, e
 			// Non-monotonic sums are converted to GCM gauges
 			return compliantName + "/gauge", nil
 		}
-		return getUnknownMetricName(metric.Sum().DataPoints(), "/counter", "counter", metric.Name(), compliantName), nil
+		return getUnknownMetricName(metric.Sum().DataPoints(), unknown, "/counter", "counter", metric.Name(), compliantName), nil
 	case pmetric.MetricTypeGauge:
-		return getUnknownMetricName(metric.Gauge().DataPoints(), "/gauge", "", metric.Name(), compliantName), nil
+		return getUnknownMetricName(metric.Gauge().DataPoints(), unknown, "/gauge", "", metric.Name(), compliantName), nil
 	case pmetric.MetricTypeSummary:
 		// summaries are sent as the following series:
 		// * Sum: prometheus.googleapis.com/<baseName>_sum/summary:counter
@@ -60,35 +61,24 @@ func (c Config) GetMetricName(baseName string, metric pmetric.Metric) (string, e
 // "/unknown" (eg, for Gauge) or "/unknown:{secondarySuffix}" (eg, "/unknown:counter" for Sum).
 // It also removes the "_total" suffix on an unknown counter, if this suffix was not present in
 // the original metric name before calling prometheus.BuildCompliantName(), which is hacky.
-// It is based on the untyped_prometheus_metric data point attribute, and behind a feature gate.
-func getUnknownMetricName(points pmetric.NumberDataPointSlice, suffix, secondarySuffix, originalName, compliantName string) string {
-	if !untypedDoubleExportFeatureGate.IsEnabled() {
-		return compliantName + suffix
-	}
-
+//
+//nolint:revive
+func getUnknownMetricName(points pmetric.NumberDataPointSlice, unknown bool, suffix, secondarySuffix, originalName, compliantName string) string {
 	nameTokens := strings.FieldsFunc(
 		originalName,
 		func(r rune) bool { return !unicode.IsLetter(r) && !unicode.IsDigit(r) },
 	)
 
-	untyped := false
 	newSuffix := suffix
-	for i := 0; i < points.Len(); i++ {
-		point := points.At(i)
-		if val, ok := point.Attributes().Get(GCPOpsAgentUntypedMetricKey); ok && val.AsString() == "true" {
-			untyped = true
-			// delete the special Ops Agent untyped attribute
-			point.Attributes().Remove(GCPOpsAgentUntypedMetricKey)
-			newSuffix = "/unknown"
-			if len(secondarySuffix) > 0 {
-				newSuffix = newSuffix + ":" + secondarySuffix
-			}
-			// even though we have the suffix, keep looping to remove the attribute from other points, if any
+	if unknown {
+		newSuffix = "/unknown"
+		if len(secondarySuffix) > 0 {
+			newSuffix = newSuffix + ":" + secondarySuffix
 		}
 	}
 
 	// de-normalize "_total" suffix for counters where not present on original metric name
-	if untyped && nameTokens[len(nameTokens)-1] != "total" && strings.HasSuffix(compliantName, "_total") {
+	if unknown && nameTokens[len(nameTokens)-1] != "total" && strings.HasSuffix(compliantName, "_total") {
 		compliantName = strings.TrimSuffix(compliantName, "_total")
 	}
 	return compliantName + newSuffix