Add WithoutCounterSuffixes option in the prometheus exporter

CHANGELOG.md

@@ -14,6 +14,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Add `PeriodicReader` struct in `go.opentelemetry.io/otel/sdk/metric`. (#4244)
 - Add `Exporter` struct in `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc`. (#4272)
 - Add `Exporter` struct in `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp`. (#4272)
+- Add `WithoutCounterSuffixes` option in `go.opentelemetry.io/otel/exporters/prometheus` to disable addition of `_total` suffixes. (#TODO)
 
 ### Changed
 

exporters/prometheus/config.go

@@ -24,12 +24,13 @@ import (
 
 // config contains options for the exporter.
 type config struct {
-	registerer        prometheus.Registerer
-	disableTargetInfo bool
-	withoutUnits      bool
-	aggregation       metric.AggregationSelector
-	disableScopeInfo  bool
-	namespace         string
+	registerer             prometheus.Registerer
+	disableTargetInfo      bool
+	withoutUnits           bool
+	withoutCounterSuffixes bool
+	aggregation            metric.AggregationSelector
+	disableScopeInfo       bool
+	namespace              string
 }
 
 // newConfig creates a validated config configured with options.
@@ -110,6 +111,19 @@ func WithoutUnits() Option {
 	})
 }
 
+// WithoutUnits disables exporter's addition _total suffixes on counters.
+//
+// By default, metric names include a _total suffix to follow Prometheus naming
+// conventions. For example, the counter metric happy.people would become
+// happy_people_total. With this option set, the name would instead be
+// happy_people.
+func WithoutCounterSuffixes() Option {
+	return optionFunc(func(cfg config) config {
+		cfg.withoutCounterSuffixes = true
+		return cfg
+	})
+}
+
 // WithoutScopeInfo configures the Exporter to not export the otel_scope_info metric.
 // If not specified, the Exporter will create a otel_scope_info metric containing
 // the metrics' Instrumentation Scope, and also add labels about Instrumentation Scope to all metric points.

exporters/prometheus/exporter.go

@@ -59,9 +59,10 @@ var _ metric.Reader = &Exporter{}
 type collector struct {
 	reader metric.Reader
 
-	withoutUnits     bool
-	disableScopeInfo bool
-	namespace        string
+	withoutUnits           bool
+	withoutCounterSuffixes bool
+	disableScopeInfo       bool
+	namespace              string
 
 	mu                sync.Mutex // mu protects all members below from the concurrent access.
 	disableTargetInfo bool
@@ -70,7 +71,7 @@ type collector struct {
 	metricFamilies    map[string]*dto.MetricFamily
 }
 
-// prometheus counters MUST have a _total suffix:
+// prometheus counters MUST have a _total suffix by default:
 // https://github.com/open-telemetry/opentelemetry-specification/blob/v1.20.0/specification/compatibility/prometheus_and_openmetrics.md
 const counterSuffix = "_total"
 
@@ -84,13 +85,14 @@ func New(opts ...Option) (*Exporter, error) {
 	reader := metric.NewManualReader(cfg.manualReaderOptions()...)
 
 	collector := &collector{
-		reader:            reader,
-		disableTargetInfo: cfg.disableTargetInfo,
-		withoutUnits:      cfg.withoutUnits,
-		disableScopeInfo:  cfg.disableScopeInfo,
-		scopeInfos:        make(map[instrumentation.Scope]prometheus.Metric),
-		metricFamilies:    make(map[string]*dto.MetricFamily),
-		namespace:         cfg.namespace,
+		reader:                 reader,
+		disableTargetInfo:      cfg.disableTargetInfo,
+		withoutUnits:           cfg.withoutUnits,
+		withoutCounterSuffixes: cfg.withoutCounterSuffixes,
+		disableScopeInfo:       cfg.disableScopeInfo,
+		scopeInfos:             make(map[instrumentation.Scope]prometheus.Metric),
+		metricFamilies:         make(map[string]*dto.MetricFamily),
+		namespace:              cfg.namespace,
 	}
 
 	if err := cfg.registerer.Register(collector); err != nil {
@@ -387,12 +389,12 @@ func (c *collector) metricTypeAndName(m metricdata.Metrics) (*dto.MetricType, st
 	case metricdata.Histogram[int64], metricdata.Histogram[float64]:
 		return dto.MetricType_HISTOGRAM.Enum(), name
 	case metricdata.Sum[float64]:
-		if v.IsMonotonic {
+		if v.IsMonotonic && !c.withoutCounterSuffixes {
 			return dto.MetricType_COUNTER.Enum(), name + counterSuffix
 		}
 		return dto.MetricType_GAUGE.Enum(), name
 	case metricdata.Sum[int64]:
-		if v.IsMonotonic {
+		if v.IsMonotonic && !c.withoutCounterSuffixes {
 			return dto.MetricType_COUNTER.Enum(), name + counterSuffix
 		}
 		return dto.MetricType_GAUGE.Enum(), name

exporters/prometheus/exporter_test.go

@@ -71,6 +71,36 @@ func TestPrometheusExporter(t *testing.T) {
 				counter.Add(ctx, 5, otelmetric.WithAttributeSet(attrs2))
 			},
 		},
+		{
+			name:         "counter with suffixes disabled",
+			expectedFile: "testdata/counter_disabled_suffix.txt",
+			options:      []Option{WithoutCounterSuffixes()},
+			recordMetrics: func(ctx context.Context, meter otelmetric.Meter) {
+				opt := otelmetric.WithAttributes(
+					attribute.Key("A").String("B"),
+					attribute.Key("C").String("D"),
+					attribute.Key("E").Bool(true),
+					attribute.Key("F").Int(42),
+				)
+				counter, err := meter.Float64Counter(
+					"foo",
+					otelmetric.WithDescription("a simple counter without a total suffix"),
+					otelmetric.WithUnit("ms"),
+				)
+				require.NoError(t, err)
+				counter.Add(ctx, 5, opt)
+				counter.Add(ctx, 10.3, opt)
+				counter.Add(ctx, 9, opt)
+
+				attrs2 := attribute.NewSet(
+					attribute.Key("A").String("D"),
+					attribute.Key("C").String("B"),
+					attribute.Key("E").Bool(true),
+					attribute.Key("F").Int(42),
+				)
+				counter.Add(ctx, 5, otelmetric.WithAttributeSet(attrs2))
+			},
+		},
 		{
 			name:         "gauge",
 			expectedFile: "testdata/gauge.txt",

exporters/prometheus/testdata/counter_disabled_suffix.txt

@@ -0,0 +1,10 @@
+# HELP foo_milliseconds a simple counter without a total suffix
+# TYPE foo_milliseconds counter
+foo_milliseconds{A="B",C="D",E="true",F="42",otel_scope_name="testmeter",otel_scope_version="v0.1.0"} 24.3
+foo_milliseconds{A="D",C="B",E="true",F="42",otel_scope_name="testmeter",otel_scope_version="v0.1.0"} 5
+# HELP otel_scope_info Instrumentation Scope metadata
+# TYPE otel_scope_info gauge
+otel_scope_info{otel_scope_name="testmeter",otel_scope_version="v0.1.0"} 1
+# HELP target_info Target metadata
+# TYPE target_info gauge
+target_info{service_name="prometheus_test",telemetry_sdk_language="go",telemetry_sdk_name="opentelemetry",telemetry_sdk_version="latest"} 1