Deprecate metric/unit and use a string for units in the metric API/SDK

CHANGELOG.md

@@ -41,6 +41,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 - [bridge/ot] Fall-back to TextMap carrier when it's not ot.HttpHeaders. (#3679)
 - The `Collect` method of the `"go.opentelemetry.io/otel/sdk/metric".Reader` interface is updated to accept the `metricdata.ResourceMetrics` value the collection will be made into. This change is made to enable memory reuse by SDK users. (#3732)
+- The `WithUnit` option in `go.opentelemetry.io/otel/sdk/metric/instrument` is updated to accept a `string` for the unit value. (#3776)
 
 ### Fixed
 
@@ -51,6 +52,14 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Data race issue in OTLP exporter retry mechanism. (#3756)
 - Fixes wrapping a nil error in some cases (#????)
 
+### Deprecated
+
+- The `go.opentelemetry.io/otel/metric/unit` package is deprecated.
+  Use the equivalent unit string instead. (#3776)
+  - Use `"1"` instead of `unit.Dimensionless`
+  - Use `"By"` instead of `unit.Bytes`
+  - Use `"ms"` instead of `unit.Milliseconds`
+
 ## [1.13.0/0.36.0] 2023-02-07
 
 ### Added

bridge/opencensus/go.mod

@@ -6,7 +6,6 @@ require (
 	github.com/stretchr/testify v1.8.2
 	go.opencensus.io v0.24.0
 	go.opentelemetry.io/otel v1.13.0
-	go.opentelemetry.io/otel/metric v0.36.0
 	go.opentelemetry.io/otel/sdk v1.13.0
 	go.opentelemetry.io/otel/sdk/metric v0.36.0
 	go.opentelemetry.io/otel/trace v1.13.0
@@ -19,6 +18,7 @@ require (
 	github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e // indirect
 	github.com/kr/pretty v0.1.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	go.opentelemetry.io/otel/metric v0.36.0 // indirect
 	golang.org/x/sys v0.5.0 // indirect
 	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect

bridge/opencensus/internal/ocmetric/metric.go

@@ -21,7 +21,6 @@ import (
 	ocmetricdata "go.opencensus.io/metric/metricdata"
 
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/metric/unit"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
@@ -52,7 +51,7 @@ func ConvertMetrics(ocmetrics []*ocmetricdata.Metric) ([]metricdata.Metrics, err
 		otelMetrics = append(otelMetrics, metricdata.Metrics{
 			Name:        ocm.Descriptor.Name,
 			Description: ocm.Descriptor.Description,
-			Unit:        convertUnit(ocm.Descriptor.Unit),
+			Unit:        string(ocm.Descriptor.Unit),
 			Data:        agg,
 		})
 	}
@@ -201,16 +200,3 @@ func convertAttrs(keys []ocmetricdata.LabelKey, values []ocmetricdata.LabelValue
 	}
 	return attribute.NewSet(attrs...), nil
 }
-
-// convertUnit converts from the OpenCensus unit to OpenTelemetry unit.
-func convertUnit(u ocmetricdata.Unit) unit.Unit {
-	switch u {
-	case ocmetricdata.UnitDimensionless:
-		return unit.Dimensionless
-	case ocmetricdata.UnitBytes:
-		return unit.Bytes
-	case ocmetricdata.UnitMilliseconds:
-		return unit.Milliseconds
-	}
-	return unit.Unit(string(u))
-}

bridge/opencensus/internal/ocmetric/metric_test.go

@@ -22,7 +22,6 @@ import (
 	ocmetricdata "go.opencensus.io/metric/metricdata"
 
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/metric/unit"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata/metricdatatest"
 )
@@ -214,7 +213,7 @@ func TestConvertMetrics(t *testing.T) {
 				{
 					Name:        "foo.com/histogram-a",
 					Description: "a testing histogram",
-					Unit:        unit.Dimensionless,
+					Unit:        "1",
 					Data: metricdata.Histogram{
 						DataPoints: []metricdata.HistogramDataPoint{
 							{
@@ -252,7 +251,7 @@ func TestConvertMetrics(t *testing.T) {
 				}, {
 					Name:        "foo.com/gauge-a",
 					Description: "an int testing gauge",
-					Unit:        unit.Bytes,
+					Unit:        "By",
 					Data: metricdata.Gauge[int64]{
 						DataPoints: []metricdata.DataPoint[int64]{
 							{
@@ -281,7 +280,7 @@ func TestConvertMetrics(t *testing.T) {
 				}, {
 					Name:        "foo.com/gauge-b",
 					Description: "a float testing gauge",
-					Unit:        unit.Bytes,
+					Unit:        "By",
 					Data: metricdata.Gauge[float64]{
 						DataPoints: []metricdata.DataPoint[float64]{
 							{
@@ -310,7 +309,7 @@ func TestConvertMetrics(t *testing.T) {
 				}, {
 					Name:        "foo.com/sum-a",
 					Description: "an int testing sum",
-					Unit:        unit.Milliseconds,
+					Unit:        "ms",
 					Data: metricdata.Sum[int64]{
 						IsMonotonic: true,
 						Temporality: metricdata.CumulativeTemporality,
@@ -341,7 +340,7 @@ func TestConvertMetrics(t *testing.T) {
 				}, {
 					Name:        "foo.com/sum-b",
 					Description: "a float testing sum",
-					Unit:        unit.Milliseconds,
+					Unit:        "ms",
 					Data: metricdata.Sum[float64]{
 						IsMonotonic: true,
 						Temporality: metricdata.CumulativeTemporality,
@@ -387,7 +386,7 @@ func TestConvertMetrics(t *testing.T) {
 				{
 					Name:        "foo.com/histogram-a",
 					Description: "a testing histogram",
-					Unit:        unit.Dimensionless,
+					Unit:        "1",
 					Data: metricdata.Histogram{
 						Temporality: metricdata.CumulativeTemporality,
 						DataPoints:  []metricdata.HistogramDataPoint{},
@@ -410,7 +409,7 @@ func TestConvertMetrics(t *testing.T) {
 				{
 					Name:        "foo.com/sum-a",
 					Description: "a testing sum",
-					Unit:        unit.Dimensionless,
+					Unit:        "1",
 					Data: metricdata.Sum[float64]{
 						IsMonotonic: true,
 						Temporality: metricdata.CumulativeTemporality,
@@ -434,7 +433,7 @@ func TestConvertMetrics(t *testing.T) {
 				{
 					Name:        "foo.com/gauge-a",
 					Description: "a testing gauge",
-					Unit:        unit.Dimensionless,
+					Unit:        "1",
 					Data: metricdata.Gauge[int64]{
 						DataPoints: []metricdata.DataPoint[int64]{},
 					},
@@ -580,38 +579,6 @@ func TestConvertMetrics(t *testing.T) {
 	}
 }
 
-func TestConvertUnits(t *testing.T) {
-	var noUnit unit.Unit
-	for _, tc := range []struct {
-		desc     string
-		input    ocmetricdata.Unit
-		expected unit.Unit
-	}{{
-		desc:     "unspecified unit",
-		expected: noUnit,
-	}, {
-		desc:     "dimensionless",
-		input:    ocmetricdata.UnitDimensionless,
-		expected: unit.Dimensionless,
-	}, {
-		desc:     "milliseconds",
-		input:    ocmetricdata.UnitMilliseconds,
-		expected: unit.Milliseconds,
-	}, {
-		desc:     "bytes",
-		input:    ocmetricdata.UnitBytes,
-		expected: unit.Bytes,
-	},
-	} {
-		t.Run(tc.desc, func(t *testing.T) {
-			output := convertUnit(tc.input)
-			if output != tc.expected {
-				t.Errorf("convertUnit(%v) = %q, want %q", tc.input, output, tc.expected)
-			}
-		})
-	}
-}
-
 func TestConvertAttributes(t *testing.T) {
 	setWithMultipleKeys := attribute.NewSet(
 		attribute.KeyValue{Key: attribute.Key("first"), Value: attribute.StringValue("1")},

exporters/otlp/otlpmetric/go.mod

@@ -7,7 +7,6 @@ require (
 	github.com/stretchr/testify v1.8.2
 	go.opentelemetry.io/otel v1.13.0
 	go.opentelemetry.io/otel/exporters/otlp/internal/retry v1.13.0
-	go.opentelemetry.io/otel/metric v0.36.0
 	go.opentelemetry.io/otel/sdk v1.13.0
 	go.opentelemetry.io/otel/sdk/metric v0.36.0
 	go.opentelemetry.io/proto/otlp v0.19.0
@@ -23,6 +22,7 @@ require (
 	github.com/golang/protobuf v1.5.2 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.7.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	go.opentelemetry.io/otel/metric v0.36.0 // indirect
 	go.opentelemetry.io/otel/trace v1.13.0 // indirect
 	golang.org/x/net v0.7.0 // indirect
 	golang.org/x/sys v0.5.0 // indirect

exporters/otlp/otlpmetric/internal/otest/client.go

@@ -27,7 +27,6 @@ import (
 
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/internal"
-	"go.opentelemetry.io/otel/metric/unit"
 	semconv "go.opentelemetry.io/otel/semconv/v1.17.0"
 	collpb "go.opentelemetry.io/proto/otlp/collector/metrics/v1"
 	cpb "go.opentelemetry.io/proto/otlp/common/v1"
@@ -118,31 +117,31 @@ var (
 		{
 			Name:        "int64-gauge",
 			Description: "Gauge with int64 values",
-			Unit:        string(unit.Dimensionless),
+			Unit:        "1",
 			Data:        &mpb.Metric_Gauge{Gauge: gaugeInt64},
 		},
 		{
 			Name:        "float64-gauge",
 			Description: "Gauge with float64 values",
-			Unit:        string(unit.Dimensionless),
+			Unit:        "1",
 			Data:        &mpb.Metric_Gauge{Gauge: gaugeFloat64},
 		},
 		{
 			Name:        "int64-sum",
 			Description: "Sum with int64 values",
-			Unit:        string(unit.Dimensionless),
+			Unit:        "1",
 			Data:        &mpb.Metric_Sum{Sum: sumInt64},
 		},
 		{
 			Name:        "float64-sum",
 			Description: "Sum with float64 values",
-			Unit:        string(unit.Dimensionless),
+			Unit:        "1",
 			Data:        &mpb.Metric_Sum{Sum: sumFloat64},
 		},
 		{
 			Name:        "histogram",
 			Description: "Histogram",
-			Unit:        string(unit.Dimensionless),
+			Unit:        "1",
 			Data:        &mpb.Metric_Histogram{Histogram: hist},
 		},
 	}

exporters/otlp/otlpmetric/internal/transform/metricdata_test.go

@@ -22,7 +22,6 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/metric/unit"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	"go.opentelemetry.io/otel/sdk/resource"
@@ -188,49 +187,49 @@ var (
 		{
 			Name:        "int64-gauge",
 			Description: "Gauge with int64 values",
-			Unit:        unit.Dimensionless,
+			Unit:        "1",
 			Data:        otelGaugeInt64,
 		},
 		{
 			Name:        "float64-gauge",
 			Description: "Gauge with float64 values",
-			Unit:        unit.Dimensionless,
+			Unit:        "1",
 			Data:        otelGaugeFloat64,
 		},
 		{
 			Name:        "int64-sum",
 			Description: "Sum with int64 values",
-			Unit:        unit.Dimensionless,
+			Unit:        "1",
 			Data:        otelSumInt64,
 		},
 		{
 			Name:        "float64-sum",
 			Description: "Sum with float64 values",
-			Unit:        unit.Dimensionless,
+			Unit:        "1",
 			Data:        otelSumFloat64,
 		},
 		{
 			Name:        "invalid-sum",
 			Description: "Sum with invalid temporality",
-			Unit:        unit.Dimensionless,
+			Unit:        "1",
 			Data:        otelSumInvalid,
 		},
 		{
 			Name:        "histogram",
 			Description: "Histogram",
-			Unit:        unit.Dimensionless,
+			Unit:        "1",
 			Data:        otelHist,
 		},
 		{
 			Name:        "invalid-histogram",
 			Description: "Invalid histogram",
-			Unit:        unit.Dimensionless,
+			Unit:        "1",
 			Data:        otelHistInvalid,
 		},
 		{
 			Name:        "unknown",
 			Description: "Unknown aggregation",
-			Unit:        unit.Dimensionless,
+			Unit:        "1",
 			Data:        unknownAgg,
 		},
 	}
@@ -239,31 +238,31 @@ var (
 		{
 			Name:        "int64-gauge",
 			Description: "Gauge with int64 values",
-			Unit:        string(unit.Dimensionless),
+			Unit:        "1",
 			Data:        &mpb.Metric_Gauge{Gauge: pbGaugeInt64},
 		},
 		{
 			Name:        "float64-gauge",
 			Description: "Gauge with float64 values",
-			Unit:        string(unit.Dimensionless),
+			Unit:        "1",
 			Data:        &mpb.Metric_Gauge{Gauge: pbGaugeFloat64},
 		},
 		{
 			Name:        "int64-sum",
 			Description: "Sum with int64 values",
-			Unit:        string(unit.Dimensionless),
+			Unit:        "1",
 			Data:        &mpb.Metric_Sum{Sum: pbSumInt64},
 		},
 		{
 			Name:        "float64-sum",
 			Description: "Sum with float64 values",
-			Unit:        string(unit.Dimensionless),
+			Unit:        "1",
 			Data:        &mpb.Metric_Sum{Sum: pbSumFloat64},
 		},
 		{
 			Name:        "histogram",
 			Description: "Histogram",
-			Unit:        string(unit.Dimensionless),
+			Unit:        "1",
 			Data:        &mpb.Metric_Histogram{Histogram: pbHist},
 		},
 	}

exporters/prometheus/exporter.go

@@ -31,7 +31,6 @@ import (
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/internal/global"
-	"go.opentelemetry.io/otel/metric/unit"
 	"go.opentelemetry.io/otel/sdk/instrumentation"
 	"go.opentelemetry.io/otel/sdk/metric"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
@@ -309,10 +308,10 @@ func sanitizeRune(r rune) rune {
 	return '_'
 }
 
-var unitSuffixes = map[unit.Unit]string{
-	unit.Dimensionless: "_ratio",
-	unit.Bytes:         "_bytes",
-	unit.Milliseconds:  "_milliseconds",
+var unitSuffixes = map[string]string{
+	"1":  "_ratio",
+	"By": "_bytes",
+	"ms": "_milliseconds",
 }
 
 // getName returns the sanitized name, including unit suffix.