go.opentelemetry.io/otel/sdk/metric v1.37.0: Aggregation

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify go.opentelemetry.io/otel/sdk/metric.Aggregation in pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0
Demonstrate these symbols/APIs:
  - go.opentelemetry.io/otel/sdk/metric.Aggregation

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:bc8b401b621e8cfd0da7fc62b582f011932157218e8575bfbb21a8a11da70e28","contract":["metric.Aggregation interface is implemented by AggregationDefault, AggregationDrop, AggregationSum, AggregationLastValue, AggregationExplicitBucketHistogram, and AggregationBase2ExponentialHistogram","metric.DefaultAggregationSelector returns the default Aggregation for each InstrumentKind","metric.WithAggregationSelector configures a ManualReader with a custom AggregationSelector mapping","metric.NewView with AggregationDrop drops recorded data for matching instruments"],"goal":"verify go.opentelemetry.io/otel/sdk/metric.Aggregation in pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0"],"schemaVersion":1,"symbols":["go.opentelemetry.io/otel/sdk/metric.Aggregation"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0","symbols":["go.opentelemetry.io/otel/sdk/metric.Aggregation"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require go.opentelemetry.io/otel/sdk/metric v1.37.0

require (
	github.com/go-logr/logr v1.4.3 // indirect
	github.com/go-logr/stdr v1.2.2 // indirect
	github.com/google/uuid v1.6.0 // indirect
	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
	go.opentelemetry.io/otel v1.37.0 // indirect
	go.opentelemetry.io/otel/metric v1.37.0 // indirect
	go.opentelemetry.io/otel/sdk v1.37.0 // indirect
	go.opentelemetry.io/otel/trace v1.37.0 // indirect
	golang.org/x/sys v0.33.0 // indirect
)

github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
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/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
go.opentelemetry.io/auto/sdk v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
go.opentelemetry.io/otel v1.37.0 h1:9zhNfelUvx0KBfu/gb+ZgeAfAgtWrfHJZcAqFC228wQ=
go.opentelemetry.io/otel v1.37.0/go.mod h1:ehE/umFRLnuLa/vSccNq9oS1ErUlkkK71gMcN34UG8I=
go.opentelemetry.io/otel/metric v1.37.0 h1:mvwbQS5m0tbmqML4NqK+e3aDiO02vsf/WgbsdpcPoZE=
go.opentelemetry.io/otel/metric v1.37.0/go.mod h1:04wGrZurHYKOc+RKeye86GwKiTb9FKm1WHtO+4EVr2E=
go.opentelemetry.io/otel/sdk v1.37.0 h1:ItB0QUqnjesGRvNcmAcU0LyvkVyGJ2xftD29bWdDvKI=
go.opentelemetry.io/otel/sdk v1.37.0/go.mod h1:VredYzxUvuo2q3WRcDnKDjbdvmO0sCzOvVAiY+yUkAg=
go.opentelemetry.io/otel/sdk/metric v1.37.0 h1:90lI228XrB9jCMuSdA0673aubgRobVZFhbjxHHspCPc=
go.opentelemetry.io/otel/sdk/metric v1.37.0/go.mod h1:cNen4ZWfiD37l5NhS+Keb5RXVWZWpRE+9WyVCpbo5ps=
go.opentelemetry.io/otel/trace v1.37.0 h1:HLdcFNbRQBE2imdSEgm/kwqmQj1Or1l/7bW6mxVK7z4=
go.opentelemetry.io/otel/trace v1.37.0/go.mod h1:TlgrlQ+PtQO5XFerSPUYG0JSgGyryXewPGyayAWSBS0=
golang.org/x/sys v0.33.0 h1:q3i8TbbEz+JRD9ywIRlyRAQbM0qF7hu24q3teo2hbuw=
golang.org/x/sys v0.33.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

package main

import (
	"context"
	"fmt"

	"go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/metric/metricdata"
)

func main() {
	defaultCounterAgg := metric.DefaultAggregationSelector(metric.InstrumentKindCounter)
	fmt.Printf("Default Counter Aggregation: %T\n", defaultCounterAgg)

	customSelector := func(ik metric.InstrumentKind) metric.Aggregation {
		if ik == metric.InstrumentKindCounter {
			return metric.AggregationExplicitBucketHistogram{
				Boundaries: []float64{5, 10, 25},
			}
		}
		return metric.DefaultAggregationSelector(ik)
	}

	reader := metric.NewManualReader(metric.WithAggregationSelector(customSelector))
	mp := metric.NewMeterProvider(metric.WithReader(reader))
	defer func() { _ = mp.Shutdown(context.Background()) }()

	meter := mp.Meter("example.com/demo")
	counter, err := meter.Int64Counter("events")
	if err != nil {
		panic(err)
	}

	ctx := context.Background()
	counter.Add(ctx, 12)

	var rm metricdata.ResourceMetrics
	if err := reader.Collect(ctx, &rm); err != nil {
		panic(err)
	}

	for _, sm := range rm.ScopeMetrics {
		for _, m := range sm.Metrics {
			fmt.Printf("Metric %s aggregated as %T\n", m.Name, m.Data)
		}
	}
}

{
  "schemaVersion": 1,
  "goal": "verify go.opentelemetry.io/otel/sdk/metric.Aggregation in pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0"
  ],
  "symbols": [
    "go.opentelemetry.io/otel/sdk/metric.Aggregation"
  ]
}

package main

import (
	"context"
	"fmt"
	"os"

	"go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/metric/metricdata"
)

func main() {
	if err := runTests(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract test failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All contract assertions passed.")
}

func runTests() error {
	// 1. metric.Aggregation interface is implemented by AggregationDefault, AggregationDrop, AggregationSum, AggregationLastValue, AggregationExplicitBucketHistogram, and AggregationBase2ExponentialHistogram
	var _ metric.Aggregation = metric.AggregationDefault{}
	var _ metric.Aggregation = metric.AggregationDrop{}
	var _ metric.Aggregation = metric.AggregationSum{}
	var _ metric.Aggregation = metric.AggregationLastValue{}
	var _ metric.Aggregation = metric.AggregationExplicitBucketHistogram{}
	var _ metric.Aggregation = metric.AggregationBase2ExponentialHistogram{}

	// 2. metric.DefaultAggregationSelector returns the default Aggregation for each InstrumentKind
	counterAgg := metric.DefaultAggregationSelector(metric.InstrumentKindCounter)
	if _, ok := counterAgg.(metric.AggregationSum); !ok {
		return fmt.Errorf("expected AggregationSum for Counter, got %T", counterAgg)
	}

	histAgg := metric.DefaultAggregationSelector(metric.InstrumentKindHistogram)
	if _, ok := histAgg.(metric.AggregationExplicitBucketHistogram); !ok {
		return fmt.Errorf("expected AggregationExplicitBucketHistogram for Histogram, got %T", histAgg)
	}

	gaugeAgg := metric.DefaultAggregationSelector(metric.InstrumentKindObservableGauge)
	if _, ok := gaugeAgg.(metric.AggregationLastValue); !ok {
		return fmt.Errorf("expected AggregationLastValue for ObservableGauge, got %T", gaugeAgg)
	}

	// 3. metric.WithAggregationSelector configures a ManualReader with a custom AggregationSelector mapping
	customSelector := func(ik metric.InstrumentKind) metric.Aggregation {
		if ik == metric.InstrumentKindCounter {
			return metric.AggregationExplicitBucketHistogram{
				Boundaries: []float64{10, 50, 100},
			}
		}
		return metric.DefaultAggregationSelector(ik)
	}
	reader := metric.NewManualReader(metric.WithAggregationSelector(customSelector))
	mp := metric.NewMeterProvider(metric.WithReader(reader))
	defer func() { _ = mp.Shutdown(context.Background()) }()

	meter := mp.Meter("example.com/test-meter")
	counter, err := meter.Int64Counter("test_counter")
	if err != nil {
		return fmt.Errorf("failed to create counter: %w", err)
	}

	ctx := context.Background()
	counter.Add(ctx, 25)

	var rm metricdata.ResourceMetrics
	if err := reader.Collect(ctx, &rm); err != nil {
		return fmt.Errorf("failed to collect: %w", err)
	}

	if len(rm.ScopeMetrics) == 0 || len(rm.ScopeMetrics[0].Metrics) == 0 {
		return fmt.Errorf("expected metrics to be collected")
	}

	if _, ok := rm.ScopeMetrics[0].Metrics[0].Data.(metricdata.Histogram[int64]); !ok {
		return fmt.Errorf("expected Histogram[int64] due to custom AggregationSelector, got %T", rm.ScopeMetrics[0].Metrics[0].Data)
	}

	// 4. metric.NewView with AggregationDrop drops recorded data for matching instruments
	dropReader := metric.NewManualReader()
	dropView := metric.NewView(
		metric.Instrument{Name: "dropped_metric"},
		metric.Stream{Aggregation: metric.AggregationDrop{}},
	)
	dropMP := metric.NewMeterProvider(
		metric.WithReader(dropReader),
		metric.WithView(dropView),
	)
	defer func() { _ = dropMP.Shutdown(context.Background()) }()

	dropMeter := dropMP.Meter("example.com/drop-meter")
	droppedCounter, err := dropMeter.Int64Counter("dropped_metric")
	if err != nil {
		return fmt.Errorf("failed to create dropped_metric: %w", err)
	}
	droppedCounter.Add(ctx, 100)

	var dropRM metricdata.ResourceMetrics
	if err := dropReader.Collect(ctx, &dropRM); err != nil {
		return fmt.Errorf("failed to collect dropReader: %w", err)
	}

	for _, sm := range dropRM.ScopeMetrics {
		for _, m := range sm.Metrics {
			if m.Name == "dropped_metric" {
				return fmt.Errorf("dropped_metric should have been dropped by AggregationDrop")
			}
		}
	}

	return nil
}