go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.43.0: initialize stdoutmetric exporter and export metrics

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: initialize stdoutmetric exporter and export metrics
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel/exporters/stdout/stdoutmetric@v1.43.0
Demonstrate these symbols/APIs:
  - stdoutmetric.New

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:ab68e10242a4bb86811f2cf6bba08c4ec347d59c9f9e1eb962bd2883ada1cd8d","contract":["stdoutmetric.New initializes exporter with default options","stdoutmetric.New initializes exporter with WithPrettyPrint, WithoutTimestamps, and WithWriter","stdoutmetric.Exporter provides default Temporality and Aggregation mappings","NewConfiguredExporter and ExportInt64Counter export metric data to output writer","Exporter Shutdown cleanly releases resources"],"goal":"initialize stdoutmetric exporter and export metrics","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/exporters/stdout/stdoutmetric@v1.43.0"],"schemaVersion":1,"symbols":["stdoutmetric.New"]},"contractCommand":["go","run","-ldflags=-w -s","./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/exporters/stdout/stdoutmetric@v1.43.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/exporters/stdout/stdoutmetric@v1.43.0","symbols":["stdoutmetric.New"],"verifierAdapter":"golang@1"}

module example.com/otel-stdoutmetric

go 1.26.6

require (
	go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.43.0
	go.opentelemetry.io/otel/sdk v1.43.0
	go.opentelemetry.io/otel/sdk/metric v1.43.0
)

require (
	github.com/cespare/xxhash/v2 v2.3.0 // indirect
	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 v1.2.1 // indirect
	go.opentelemetry.io/otel v1.43.0 // indirect
	go.opentelemetry.io/otel/metric v1.43.0 // indirect
	go.opentelemetry.io/otel/trace v1.43.0 // indirect
	golang.org/x/sys v0.42.0 // indirect
)

github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
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 v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
go.opentelemetry.io/auto/sdk v1.2.1 h1:jXsnJ4Lmnqd11kwkBV2LgLoFMZKizbCi5fNZ/ipaZ64=
go.opentelemetry.io/auto/sdk v1.2.1/go.mod h1:KRTj+aOaElaLi+wW1kO/DZRXwkF4C5xPbEe3ZiIhN7Y=
go.opentelemetry.io/otel v1.43.0 h1:mYIM03dnh5zfN7HautFE4ieIig9amkNANT+xcVxAj9I=
go.opentelemetry.io/otel v1.43.0/go.mod h1:JuG+u74mvjvcm8vj8pI5XiHy1zDeoCS2LB1spIq7Ay0=
go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.43.0 h1:TC+BewnDpeiAmcscXbGMfxkO+mwYUwE/VySwvw88PfA=
go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.43.0/go.mod h1:J/ZyF4vfPwsSr9xJSPyQ4LqtcTPULFR64KwTikGLe+A=
go.opentelemetry.io/otel/metric v1.43.0 h1:d7638QeInOnuwOONPp4JAOGfbCEpYb+K6DVWvdxGzgM=
go.opentelemetry.io/otel/metric v1.43.0/go.mod h1:RDnPtIxvqlgO8GRW18W6Z/4P462ldprJtfxHxyKd2PY=
go.opentelemetry.io/otel/sdk v1.43.0 h1:pi5mE86i5rTeLXqoF/hhiBtUNcrAGHLKQdhg4h4V9Dg=
go.opentelemetry.io/otel/sdk v1.43.0/go.mod h1:P+IkVU3iWukmiit/Yf9AWvpyRDlUeBaRg6Y+C58QHzg=
go.opentelemetry.io/otel/sdk/metric v1.43.0 h1:S88dyqXjJkuBNLeMcVPRFXpRw2fuwdvfCGLEo89fDkw=
go.opentelemetry.io/otel/sdk/metric v1.43.0/go.mod h1:C/RJtwSEJ5hzTiUz5pXF1kILHStzb9zFlIEe85bhj6A=
go.opentelemetry.io/otel/trace v1.43.0 h1:BkNrHpup+4k4w+ZZ86CZoHHEkohws8AY+WTX09nk+3A=
go.opentelemetry.io/otel/trace v1.43.0/go.mod h1:/QJhyVBUUswCphDVxq+8mld+AvhXZLhe+8WVFxiFff0=
golang.org/x/sys v0.42.0 h1:omrd2nAlyT5ESRdCLYdm3+fMfNFE/+Rf4bDIQImRJeo=
golang.org/x/sys v0.42.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

{
  "schemaVersion": 1,
  "goal": "initialize stdoutmetric exporter and export metrics",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/exporters/stdout/stdoutmetric@v1.43.0"
  ],
  "symbols": [
    "stdoutmetric.New"
  ]
}

package sample

import (
	"context"
	"fmt"
	"io"

	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
	"go.opentelemetry.io/otel/sdk/instrumentation"
	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/metric/metricdata"
)

// ExporterWrapper provides helper utilities around a stdoutmetric Exporter.
type ExporterWrapper struct {
	Exporter sdkmetric.Exporter
}

// NewExporter creates a stdoutmetric exporter configured with the provided options.
func NewExporter(opts ...stdoutmetric.Option) (*ExporterWrapper, error) {
	exp, err := stdoutmetric.New(opts...)
	if err != nil {
		return nil, fmt.Errorf("failed to create stdoutmetric exporter: %w", err)
	}
	return &ExporterWrapper{Exporter: exp}, nil
}

// NewConfiguredExporter creates a stdoutmetric exporter writing formatted JSON to w.
func NewConfiguredExporter(w io.Writer, pretty bool, withoutTimestamps bool) (*ExporterWrapper, error) {
	opts := []stdoutmetric.Option{
		stdoutmetric.WithWriter(w),
	}
	if pretty {
		opts = append(opts, stdoutmetric.WithPrettyPrint())
	}
	if withoutTimestamps {
		opts = append(opts, stdoutmetric.WithoutTimestamps())
	}
	return NewExporter(opts...)
}

// ExportInt64Counter exports a simple int64 counter metric with the given scope and metric name.
func (w *ExporterWrapper) ExportInt64Counter(ctx context.Context, scopeName, metricName, desc string, val int64) error {
	rm := &metricdata.ResourceMetrics{
		ScopeMetrics: []metricdata.ScopeMetrics{
			{
				Scope: instrumentation.Scope{
					Name: scopeName,
				},
				Metrics: []metricdata.Metrics{
					{
						Name:        metricName,
						Description: desc,
						Unit:        "1",
						Data: metricdata.Sum[int64]{
							Temporality: metricdata.CumulativeTemporality,
							IsMonotonic: true,
							DataPoints: []metricdata.DataPoint[int64]{
								{
									Value: val,
								},
							},
						},
					},
				},
			},
		},
	}
	return w.Exporter.Export(ctx, rm)
}

// Shutdown flushes and stops the exporter.
func (w *ExporterWrapper) Shutdown(ctx context.Context) error {
	return w.Exporter.Shutdown(ctx)
}

package main

import (
	"bytes"
	"context"
	"fmt"
	"os"
	"strings"

	sample "example.com/otel-stdoutmetric"
	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/metric/metricdata"
)

func main() {
	ctx := context.Background()

	// 1. stdoutmetric.New initializes exporter with default options
	expDefault, err := stdoutmetric.New()
	if err != nil {
		fmt.Fprintf(os.Stderr, "stdoutmetric.New default failed: %v\n", err)
		os.Exit(1)
	}
	if expDefault == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil default exporter\n")
		os.Exit(1)
	}

	// 2. stdoutmetric.New initializes exporter with WithPrettyPrint, WithoutTimestamps, and WithWriter
	var buf bytes.Buffer
	expCustom, err := stdoutmetric.New(
		stdoutmetric.WithWriter(&buf),
		stdoutmetric.WithPrettyPrint(),
		stdoutmetric.WithoutTimestamps(),
	)
	if err != nil {
		fmt.Fprintf(os.Stderr, "stdoutmetric.New with custom options failed: %v\n", err)
		os.Exit(1)
	}
	if expCustom == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil custom exporter\n")
		os.Exit(1)
	}

	// 3. stdoutmetric.Exporter provides default Temporality and Aggregation mappings
	temporality := expCustom.Temporality(sdkmetric.InstrumentKindCounter)
	if temporality != metricdata.CumulativeTemporality {
		fmt.Fprintf(os.Stderr, "unexpected default temporality: got %v, want %v\n", temporality, metricdata.CumulativeTemporality)
		os.Exit(1)
	}

	aggregation := expCustom.Aggregation(sdkmetric.InstrumentKindCounter)
	if _, ok := aggregation.(sdkmetric.AggregationSum); !ok {
		fmt.Fprintf(os.Stderr, "unexpected default aggregation: %T\n", aggregation)
		os.Exit(1)
	}

	// 4. NewConfiguredExporter and ExportInt64Counter export metric data to output writer
	var wrapperBuf bytes.Buffer
	wrapper, err := sample.NewConfiguredExporter(&wrapperBuf, true, true)
	if err != nil {
		fmt.Fprintf(os.Stderr, "sample.NewConfiguredExporter failed: %v\n", err)
		os.Exit(1)
	}

	err = wrapper.ExportInt64Counter(ctx, "example.com/test-scope", "http_requests_total", "Total requests", 42)
	if err != nil {
		fmt.Fprintf(os.Stderr, "wrapper.ExportInt64Counter failed: %v\n", err)
		os.Exit(1)
	}

	output := wrapperBuf.String()
	if !strings.Contains(output, "http_requests_total") {
		fmt.Fprintf(os.Stderr, "expected output to contain http_requests_total, got: %s\n", output)
		os.Exit(1)
	}
	if !strings.Contains(output, "42") {
		fmt.Fprintf(os.Stderr, "expected output to contain 42, got: %s\n", output)
		os.Exit(1)
	}

	// 5. Exporter Shutdown cleanly releases resources
	if err := wrapper.Shutdown(ctx); err != nil {
		fmt.Fprintf(os.Stderr, "wrapper.Shutdown failed: %v\n", err)
		os.Exit(1)
	}

	fmt.Println("All contract assertions passed.")
}