autoexport: Add support for metrics

CHANGELOG.md

@@ -14,12 +14,17 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Add `"go.opentelemetry.io/contrib/samplers/jaegerremote".WithSamplingStrategyFetcher` which sets custom fetcher implementation. (#4045)
 - Add `"go.opentelemetry.io/contrib/config"` package that includes configuration models generated via go-jsonschema. (#4376)
 - Add `NewSDK` function to `"go.opentelemetry.io/contrib/config"`. The initial implementation only returns noop providers. (#4414)
+- Add metrics support to `go.opentelemetry.io/contrib/exporters/autoexport`. (#4229)
 
 ### Changed
 
 - Dropped compatibility testing for [Go 1.19].
   The project no longer guarantees support for this version of Go. (#4352)
 
+### Deprecated
+
+- In `go.opentelemetry.io/contrib/exporters/autoexport`, `Option` was renamed to `SpanOption`. The old name is deprecated but continues to be supported as an alias. (#4229)
+
 ### Fixed
 
 - The `go.opentelemetry.io/contrib/samplers/jaegerremote` sampler does not panic when the default HTTP round-tripper (`http.DefaultTransport`) is not `*http.Transport`. (#4045)

exporters/autoexport/go.mod

@@ -4,11 +4,13 @@ go 1.20
 
 require (
 	github.com/stretchr/testify v1.8.4
+	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v0.42.0
+	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v0.42.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.19.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.19.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.19.0
-	go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.19.0
 	go.opentelemetry.io/otel/sdk v1.19.0
+	go.opentelemetry.io/otel/sdk/metric v1.19.0
 )
 
 require (
@@ -20,6 +22,7 @@ require (
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.16.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	go.opentelemetry.io/otel v1.19.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlpmetric v0.42.0 // indirect
 	go.opentelemetry.io/otel/metric v1.19.0 // indirect
 	go.opentelemetry.io/otel/trace v1.19.0 // indirect
 	go.opentelemetry.io/proto/otlp v1.0.0 // indirect

exporters/autoexport/go.sum

@@ -24,18 +24,24 @@ github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcU
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 go.opentelemetry.io/otel v1.19.0 h1:MuS/TNf4/j4IXsZuJegVzI1cwut7Qc00344rgH7p8bs=
 go.opentelemetry.io/otel v1.19.0/go.mod h1:i0QyjOq3UPoTzff0PJB2N66fb4S0+rSbSB15/oyH9fY=
+go.opentelemetry.io/otel/exporters/otlp/otlpmetric v0.42.0 h1:ZtfnDL+tUrs1F0Pzfwbg2d59Gru9NCH3bgSHBM6LDwU=
+go.opentelemetry.io/otel/exporters/otlp/otlpmetric v0.42.0/go.mod h1:hG4Fj/y8TR/tlEDREo8tWstl9fO9gcFkn4xrx0Io8xU=
+go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v0.42.0 h1:NmnYCiR0qNufkldjVvyQfZTHSdzeHoZ41zggMsdMcLM=
+go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v0.42.0/go.mod h1:UVAO61+umUsHLtYb8KXXRoHtxUkdOPkYidzW3gipRLQ=
+go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v0.42.0 h1:wNMDy/LVGLj2h3p6zg4d0gypKfWKSWI14E1C4smOgl8=
+go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v0.42.0/go.mod h1:YfbDdXAAkemWJK3H/DshvlrxqFB2rtW4rY6ky/3x/H0=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.19.0 h1:Mne5On7VWdx7omSrSSZvM4Kw7cS7NQkOOmLcgscI51U=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.19.0/go.mod h1:IPtUMKL4O3tH5y+iXVyAXqpAwMuzC1IrxVS81rummfE=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.19.0 h1:3d+S281UTjM+AbF31XSOYn1qXn3BgIdWl8HNEpx08Jk=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.19.0/go.mod h1:0+KuTDyKL4gjKCF75pHOX4wuzYDUZYfAQdSu43o+Z2I=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.19.0 h1:IeMeyr1aBvBiPVYihXIaeIZba6b8E1bYp7lbdxK8CQg=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.19.0/go.mod h1:oVdCUtjq9MK9BlS7TtucsQwUcXcymNiEDjgDD2jMtZU=
-go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.19.0 h1:Nw7Dv4lwvGrI68+wULbcq7su9K2cebeCUrDjVrUJHxM=
-go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.19.0/go.mod h1:1MsF6Y7gTqosgoZvHlzcaaM8DIMNZgJh87ykokoNH7Y=
 go.opentelemetry.io/otel/metric v1.19.0 h1:aTzpGtV0ar9wlV4Sna9sdJyII5jTVJEvKETPiOKwvpE=
 go.opentelemetry.io/otel/metric v1.19.0/go.mod h1:L5rUsV9kM1IxCj1MmSdS+JQAcVm319EUrDVLrt7jqt8=
 go.opentelemetry.io/otel/sdk v1.19.0 h1:6USY6zH+L8uMH8L3t1enZPR3WFEmSTADlqldyHtJi3o=
 go.opentelemetry.io/otel/sdk v1.19.0/go.mod h1:NedEbbS4w3C6zElbLdPJKOpJQOrGUJ+GfzpjUvI0v1A=
+go.opentelemetry.io/otel/sdk/metric v1.19.0 h1:EJoTO5qysMsYCa+w4UghwFV/ptQgqSL/8Ni+hx+8i1k=
+go.opentelemetry.io/otel/sdk/metric v1.19.0/go.mod h1:XjG0jQyFJrv2PbMvwND7LwCEhsJzCzV5210euduKcKY=
 go.opentelemetry.io/otel/trace v1.19.0 h1:DFVQmlVbfVeOuBRrwdtaehRrWiL1JoVs9CPIQ1Dzxpg=
 go.opentelemetry.io/otel/trace v1.19.0/go.mod h1:mfaSyvGyEJEI0nyV2I4qhNQnbBOUUmYZpYojqMnX2vo=
 go.opentelemetry.io/proto/otlp v1.0.0 h1:T0TX0tmXU8a3CbNXzEKGeU5mIVOdf0oykP+u2lIVU/I=

exporters/autoexport/metrics.go

@@ -0,0 +1,97 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package autoexport // import "go.opentelemetry.io/contrib/exporters/autoexport"
+
+import (
+	"context"
+	"os"
+
+	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
+	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp"
+	"go.opentelemetry.io/otel/sdk/metric"
+)
+
+// MetricOption applies an autoexport configuration option.
+type MetricOption = option[metric.Reader]
+
+// WithFallbackMetricReader sets the fallback exporter to use when no exporter
+// is configured through the OTEL_METRICS_EXPORTER environment variable.
+func WithFallbackMetricReader(exporter metric.Reader) MetricOption {
+	return withFallback[metric.Reader](exporter)
+}
+
+// NewMetricReader returns a configured [go.opentelemetry.io/otel/sdk/metric.Reader]
+// defined using the environment variables described below.
+//
+// OTEL_METRICS_EXPORTER defines the metrics exporter; supported values:
+//   - "none" - "no operation" exporter
+//   - "otlp" (default) - OTLP exporter; see [go.opentelemetry.io/otel/exporters/otlp/otlpmetric]
+//
+// OTEL_EXPORTER_OTLP_PROTOCOL defines OTLP exporter's transport protocol;
+// supported values:
+//   - "grpc" - protobuf-encoded data using gRPC wire format over HTTP/2 connection;
+//     see: [go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc]
+//   - "http/protobuf" (default) -  protobuf-encoded data over HTTP connection;
+//     see: [go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp]
+//
+// An error is returned if an environment value is set to an unhandled value.
+//
+// Use [RegisterMetricReader] to handle more values of OTEL_METRICS_EXPORTER.
+//
+// Use [WithFallbackMetricReader] option to change the returned exporter
+// when OTEL_TRACES_EXPORTER is unset or empty.
+//
+// Use [IsNoneMetricReader] to check if the retured exporter is a "no operation" exporter.
+func NewMetricReader(ctx context.Context, opts ...MetricOption) (metric.Reader, error) {
+	return metricsSignal.create(ctx, opts...)
+}
+
+// RegisterMetricReader sets the MetricReader factory to be used when the
+// OTEL_METRICS_EXPORTERS environment variable contains the exporter name. This
+// will panic if name has already been registered.
+func RegisterMetricReader(name string, factory func(context.Context) (metric.Reader, error)) {
+	must(metricsSignal.registry.store(name, factory))
+}
+
+var metricsSignal = newSignal[metric.Reader]("OTEL_METRICS_EXPORTER")
+
+func init() {
+	RegisterMetricReader("otlp", func(ctx context.Context) (metric.Reader, error) {
+		proto := os.Getenv(otelExporterOTLPProtoEnvKey)
+		if proto == "" {
+			proto = "http/protobuf"
+		}
+
+		switch proto {
+		case "grpc":
+			r, err := otlpmetricgrpc.New(ctx)
+			if err != nil {
+				return nil, err
+			}
+			return metric.NewPeriodicReader(r), nil
+		case "http/protobuf":
+			r, err := otlpmetrichttp.New(ctx)
+			if err != nil {
+				return nil, err
+			}
+			return metric.NewPeriodicReader(r), nil
+		default:
+			return nil, errInvalidOTLPProtocol
+		}
+	})
+	RegisterMetricReader("none", func(ctx context.Context) (metric.Reader, error) {
+		return newNoopMetricReader(), nil
+	})
+}

exporters/autoexport/metrics_test.go

@@ -0,0 +1,65 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package autoexport // import "go.opentelemetry.io/contrib/exporters/autoexport"
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+	"testing"
+
+	"go.opentelemetry.io/otel/sdk/metric"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMetricExporterNone(t *testing.T) {
+	t.Setenv("OTEL_METRICS_EXPORTER", "none")
+	got, err := NewMetricReader(context.Background())
+	assert.NoError(t, err)
+	assert.True(t, IsNoneMetricReader(got))
+}
+
+func TestMetricExporterOTLP(t *testing.T) {
+	t.Setenv("OTEL_METRICS_EXPORTER", "otlp")
+
+	for _, tc := range []struct {
+		protocol, exporterType string
+	}{
+		{"http/protobuf", "*otlpmetrichttp.Exporter"},
+		{"", "*otlpmetrichttp.Exporter"},
+		{"grpc", "*otlpmetricgrpc.Exporter"},
+	} {
+		t.Run(fmt.Sprintf("protocol=%q", tc.protocol), func(t *testing.T) {
+			t.Setenv("OTEL_EXPORTER_OTLP_PROTOCOL", tc.protocol)
+
+			got, err := NewMetricReader(context.Background())
+			assert.NoError(t, err)
+			assert.IsType(t, &metric.PeriodicReader{}, got)
+
+			// Implementation detail hack. This may break when bumping OTLP exporter modules as it uses unexported API.
+			exporterType := reflect.Indirect(reflect.ValueOf(got)).FieldByName("exporter").Elem().Type()
+			assert.Equal(t, tc.exporterType, exporterType.String())
+		})
+	}
+}
+
+func TestMetricExporterOTLPOverInvalidProtocol(t *testing.T) {
+	t.Setenv("OTEL_METRICS_EXPORTER", "otlp")
+	t.Setenv("OTEL_EXPORTER_OTLP_PROTOCOL", "invalid-protocol")
+
+	_, err := NewMetricReader(context.Background())
+	assert.Error(t, err)
+}