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

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.Reader 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.Reader

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:d9c47ad8f74b1706de17336ff5629008067f327993457d6a093b508d47183a03","contract":["NewManualReader creates a Reader implementation satisfying sdkmetric.Reader","WithReader registers an sdkmetric.Reader with a MeterProvider","Reader.Collect gathers recorded measurements into ResourceMetrics","Reader.Shutdown terminates the Reader and subsequent Collect calls return ErrReaderShutdown"],"goal":"verify go.opentelemetry.io/otel/sdk/metric.Reader 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.Reader"]},"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.Reader"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require (
	go.opentelemetry.io/otel v1.37.0
	go.opentelemetry.io/otel/metric v1.37.0
	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/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 sample

import (
	"context"
	"errors"
	"fmt"

	"go.opentelemetry.io/otel/attribute"
	otelmetric "go.opentelemetry.io/otel/metric"
	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/metric/metricdata"
)

// ReaderHolder wraps an OpenTelemetry metric.Reader and associated MeterProvider.
type ReaderHolder struct {
	Reader   sdkmetric.Reader
	Provider *sdkmetric.MeterProvider
}

// NewReaderHolder creates a ManualReader as an sdkmetric.Reader and attaches it to a MeterProvider.
func NewReaderHolder() (*ReaderHolder, error) {
	reader := sdkmetric.NewManualReader()
	if reader == nil {
		return nil, errors.New("failed to initialize manual reader")
	}

	// Verify reader satisfies sdkmetric.Reader interface
	var _ sdkmetric.Reader = reader

	provider := sdkmetric.NewMeterProvider(
		sdkmetric.WithReader(reader),
	)
	if provider == nil {
		return nil, errors.New("failed to initialize meter provider")
	}

	return &ReaderHolder{
		Reader:   reader,
		Provider: provider,
	}, nil
}

// RecordMeasurement creates a counter and records a measurement.
func (h *ReaderHolder) RecordMeasurement(ctx context.Context, metricName string, value int64, attrs ...attribute.KeyValue) error {
	if h.Provider == nil {
		return errors.New("nil provider")
	}
	meter := h.Provider.Meter("sample-meter")
	counter, err := meter.Int64Counter(metricName)
	if err != nil {
		return fmt.Errorf("create counter: %w", err)
	}
	counter.Add(ctx, value, otelmetric.WithAttributes(attrs...))
	return nil
}

// Collect reads metric data from the underlying Reader into rm.
func (h *ReaderHolder) Collect(ctx context.Context, rm *metricdata.ResourceMetrics) error {
	if h.Reader == nil {
		return errors.New("nil reader")
	}
	return h.Reader.Collect(ctx, rm)
}

// Shutdown shuts down the Reader.
func (h *ReaderHolder) Shutdown(ctx context.Context) error {
	if h.Reader == nil {
		return errors.New("nil reader")
	}
	return h.Reader.Shutdown(ctx)
}

{
  "schemaVersion": 1,
  "goal": "verify go.opentelemetry.io/otel/sdk/metric.Reader 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.Reader"
  ]
}

package main

import (
	"context"
	"errors"
	"fmt"
	"os"

	"go.opentelemetry.io/otel/attribute"
	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/metric/metricdata"
	"sample"
)

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

func runContract() error {
	ctx := context.Background()

	// 1. NewManualReader creates a Reader implementation satisfying sdkmetric.Reader
	reader := sdkmetric.NewManualReader()
	if reader == nil {
		return fmt.Errorf("expected non-nil ManualReader")
	}
	var r sdkmetric.Reader = reader
	if r == nil {
		return fmt.Errorf("expected non-nil sdkmetric.Reader")
	}

	// 2. WithReader registers an sdkmetric.Reader with a MeterProvider
	holder, err := sample.NewReaderHolder()
	if err != nil {
		return fmt.Errorf("failed to create ReaderHolder: %w", err)
	}
	if holder.Reader == nil || holder.Provider == nil {
		return fmt.Errorf("expected non-nil Reader and Provider in holder")
	}

	// 3. Reader.Collect gathers recorded measurements into ResourceMetrics
	if err := holder.RecordMeasurement(ctx, "items_processed", 10, attribute.String("status", "ok")); err != nil {
		return fmt.Errorf("failed to record measurement: %w", err)
	}

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

	if len(rm.ScopeMetrics) == 0 {
		return fmt.Errorf("expected non-empty ScopeMetrics")
	}
	if len(rm.ScopeMetrics[0].Metrics) == 0 {
		return fmt.Errorf("expected non-empty Metrics")
	}
	metric := rm.ScopeMetrics[0].Metrics[0]
	if metric.Name != "items_processed" {
		return fmt.Errorf("expected metric name 'items_processed', got %q", metric.Name)
	}
	sumData, ok := metric.Data.(metricdata.Sum[int64])
	if !ok {
		return fmt.Errorf("expected metric data type metricdata.Sum[int64], got %T", metric.Data)
	}
	if len(sumData.DataPoints) == 0 || sumData.DataPoints[0].Value != 10 {
		return fmt.Errorf("expected data point value 10, got %v", sumData.DataPoints)
	}

	// 4. Reader.Shutdown terminates the Reader and subsequent Collect calls return ErrReaderShutdown
	if err := holder.Shutdown(ctx); err != nil {
		return fmt.Errorf("reader shutdown failed: %w", err)
	}

	var afterShutdownRm metricdata.ResourceMetrics
	err = holder.Collect(ctx, &afterShutdownRm)
	if err == nil {
		return fmt.Errorf("expected error when collecting from shutdown reader, got nil")
	}
	if !errors.Is(err, sdkmetric.ErrReaderShutdown) {
		return fmt.Errorf("expected ErrReaderShutdown, got %v", err)
	}

	return nil
}