expand the set of units supported by the prometheus exporter, and avoid

duplicate unit suffixes

CHANGELOG.md

@@ -19,6 +19,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Add info and debug logging to the metric SDK. (#4315)
 - The `go.opentelemetry.io/otel/semconv/v1.21.0` package.
   The package contains semantic conventions from the `v1.21.0` version of the OpenTelemetry Semantic Conventions. (#4362)
+- Expand the set of units supported by the prometheus exporter, and don't add unit suffixes if they are already present in `go.opentelemetry.op/otel/exporters/prometheus` (#4374)
 
 ### Changed
 

exporters/prometheus/exporter.go

@@ -330,9 +330,45 @@ func sanitizeRune(r rune) rune {
 }
 
 var unitSuffixes = map[string]string{
-	"1":  "_ratio",
-	"By": "_bytes",
-	"ms": "_milliseconds",
+	// Time
+	"d":   "_days",
+	"h":   "_hours",
+	"min": "_minutes",
+	"s":   "_seconds",
+	"ms":  "_milliseconds",
+	"us":  "_microseconds",
+	"ns":  "_nanoseconds",
+
+	// Bytes
+	"By":   "_bytes",
+	"KiBy": "_kibibytes",
+	"MiBy": "_mebibytes",
+	"GiBy": "_gibibytes",
+	"TiBy": "_tibibytes",
+	"KBy":  "_kilobytes",
+	"MBy":  "_megabytes",
+	"GBy":  "_gigabytes",
+	"TBy":  "_terabytes",
+	"B":    "_bytes",
+	"KB":   "_kilobytes",
+	"MB":   "_megabytes",
+	"GB":   "_gigabytes",
+	"TB":   "_terabytes",
+
+	// SI
+	"m": "_meters",
+	"V": "_volts",
+	"A": "_amperes",
+	"J": "_joules",
+	"W": "_watts",
+	"g": "_grams",
+
+	// Misc
+	"Cel": "_celsius",
+	"Hz":  "_hertz",
+	"1":   "_ratio",
+	"%":   "_percent",
+	"$":   "_dollars",
 }
 
 // getName returns the sanitized name, prefixed with the namespace and suffixed with unit.
@@ -344,7 +380,7 @@ func (c *collector) getName(m metricdata.Metrics) string {
 	if c.withoutUnits {
 		return name
 	}
-	if suffix, ok := unitSuffixes[m.Unit]; ok {
+	if suffix, ok := unitSuffixes[m.Unit]; ok && !strings.HasSuffix(name, suffix) {
 		name += suffix
 	}
 	return name

exporters/prometheus/exporter_test.go

@@ -55,7 +55,36 @@ func TestPrometheusExporter(t *testing.T) {
 				counter, err := meter.Float64Counter(
 					"foo",
 					otelmetric.WithDescription("a simple counter"),
-					otelmetric.WithUnit("ms"),
+					otelmetric.WithUnit("s"),
+				)
+				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:         "counter that already has the unit suffix",
+			expectedFile: "testdata/counter.txt",
+			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.seconds",
+					otelmetric.WithDescription("a simple counter"),
+					otelmetric.WithUnit("s"),
 				)
 				require.NoError(t, err)
 				counter.Add(ctx, 5, opt)
@@ -85,7 +114,7 @@ func TestPrometheusExporter(t *testing.T) {
 				counter, err := meter.Float64Counter(
 					"foo",
 					otelmetric.WithDescription("a simple counter without a total suffix"),
-					otelmetric.WithUnit("ms"),
+					otelmetric.WithUnit("s"),
 				)
 				require.NoError(t, err)
 				counter.Add(ctx, 5, opt)
@@ -415,15 +444,15 @@ func TestMultiScopes(t *testing.T) {
 	fooCounter, err := provider.Meter("meterfoo", otelmetric.WithInstrumentationVersion("v0.1.0")).
 		Int64Counter(
 			"foo",
-			otelmetric.WithUnit("ms"),
+			otelmetric.WithUnit("s"),
 			otelmetric.WithDescription("meter foo counter"))
 	assert.NoError(t, err)
 	fooCounter.Add(ctx, 100, otelmetric.WithAttributes(attribute.String("type", "foo")))
 
 	barCounter, err := provider.Meter("meterbar", otelmetric.WithInstrumentationVersion("v0.1.0")).
 		Int64Counter(
 			"bar",
-			otelmetric.WithUnit("ms"),
+			otelmetric.WithUnit("s"),
 			otelmetric.WithDescription("meter bar counter"))
 	assert.NoError(t, err)
 	barCounter.Add(ctx, 200, otelmetric.WithAttributes(attribute.String("type", "bar")))
@@ -571,7 +600,7 @@ func TestDuplicateMetrics(t *testing.T) {
 				bazA.Add(ctx, 100, withTypeBar)
 
 				bazB, err := meterB.Int64Counter("bar",
-					otelmetric.WithUnit("ms"),
+					otelmetric.WithUnit("s"),
 					otelmetric.WithDescription("meter bar"))
 				assert.NoError(t, err)
 				bazB.Add(ctx, 100, withTypeBar)
@@ -589,7 +618,7 @@ func TestDuplicateMetrics(t *testing.T) {
 				barA.Add(ctx, 100, withTypeBar)
 
 				barB, err := meterB.Int64UpDownCounter("bar",
-					otelmetric.WithUnit("ms"),
+					otelmetric.WithUnit("s"),
 					otelmetric.WithDescription("meter gauge bar"))
 				assert.NoError(t, err)
 				barB.Add(ctx, 100, withTypeBar)
@@ -607,7 +636,7 @@ func TestDuplicateMetrics(t *testing.T) {
 				barA.Record(ctx, 100, withAB)
 
 				barB, err := meterB.Int64Histogram("bar",
-					otelmetric.WithUnit("ms"),
+					otelmetric.WithUnit("s"),
 					otelmetric.WithDescription("meter histogram bar"))
 				assert.NoError(t, err)
 				barB.Record(ctx, 100, withAB)

exporters/prometheus/testdata/counter.txt

@@ -1,7 +1,7 @@
-# HELP foo_milliseconds_total a simple counter
-# TYPE foo_milliseconds_total counter
-foo_milliseconds_total{A="B",C="D",E="true",F="42",otel_scope_name="testmeter",otel_scope_version="v0.1.0"} 24.3
-foo_milliseconds_total{A="D",C="B",E="true",F="42",otel_scope_name="testmeter",otel_scope_version="v0.1.0"} 5
+# HELP foo_seconds_total a simple counter
+# TYPE foo_seconds_total counter
+foo_seconds_total{A="B",C="D",E="true",F="42",otel_scope_name="testmeter",otel_scope_version="v0.1.0"} 24.3
+foo_seconds_total{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

exporters/prometheus/testdata/counter_disabled_suffix.txt

@@ -1,7 +1,7 @@
-# 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 foo_seconds a simple counter without a total suffix
+# TYPE foo_seconds counter
+foo_seconds{A="B",C="D",E="true",F="42",otel_scope_name="testmeter",otel_scope_version="v0.1.0"} 24.3
+foo_seconds{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

exporters/prometheus/testdata/multi_scopes.txt

@@ -1,9 +1,9 @@
-# HELP bar_milliseconds_total meter bar counter
-# TYPE bar_milliseconds_total counter
-bar_milliseconds_total{otel_scope_name="meterbar",otel_scope_version="v0.1.0",type="bar"} 200
-# HELP foo_milliseconds_total meter foo counter
-# TYPE foo_milliseconds_total counter
-foo_milliseconds_total{otel_scope_name="meterfoo",otel_scope_version="v0.1.0",type="foo"} 100
+# HELP bar_seconds_total meter bar counter
+# TYPE bar_seconds_total counter
+bar_seconds_total{otel_scope_name="meterbar",otel_scope_version="v0.1.0",type="bar"} 200
+# HELP foo_seconds_total meter foo counter
+# TYPE foo_seconds_total counter
+foo_seconds_total{otel_scope_name="meterfoo",otel_scope_version="v0.1.0",type="foo"} 100
 # HELP otel_scope_info Instrumentation Scope metadata
 # TYPE otel_scope_info gauge
 otel_scope_info{otel_scope_name="meterfoo",otel_scope_version="v0.1.0"} 1