go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.43.0: Exporter.MarshalLog

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 stdouttrace.Exporter.MarshalLog in pkg:golang/go.opentelemetry.io/otel/exporters/stdout/stdouttrace@v1.43.0
Kind: HOW

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

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:a27af2ccc62fe6f9da97ea33b213ad6976e0a1b934ae014cc17ef37d44c4884a","contract":["stdouttrace.Exporter.MarshalLog returns structured logging metadata with Type stdout and WithTimestamps set to true by default","stdouttrace.Exporter.MarshalLog returns WithTimestamps set to false when configured with stdouttrace.WithoutTimestamps","stdouttrace.Exporter.MarshalLog returns a valid non-nil logging structure","stdouttrace.Exporter shuts down cleanly after log inspection"],"goal":"verify stdouttrace.Exporter.MarshalLog in pkg:golang/go.opentelemetry.io/otel/exporters/stdout/stdouttrace@v1.43.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/exporters/stdout/stdouttrace@v1.43.0"],"schemaVersion":1,"symbols":["stdouttrace.Exporter.MarshalLog"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","packageManagerVersion":"1.26.6","runtime":"go","runtimeVersion":"1.26.6","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/go.opentelemetry.io/otel/exporters/stdout/stdouttrace@v1.43.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/exporters/stdout/stdouttrace@v1.43.0","symbols":["stdouttrace.Exporter.MarshalLog"],"verifierAdapter":"golang@1"}

package sample

import (
	"context"
	"fmt"

	"go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
)

// CreateExporter initializes a new stdouttrace.Exporter with optional options.
func CreateExporter(opts ...stdouttrace.Option) (*stdouttrace.Exporter, error) {
	return stdouttrace.New(opts...)
}

// GetLogMetadata extracts structured logging metadata from an Exporter using MarshalLog.
func GetLogMetadata(exp *stdouttrace.Exporter) (any, error) {
	if exp == nil {
		return nil, fmt.Errorf("exporter cannot be nil")
	}
	return exp.MarshalLog(), nil
}

// ShutdownExporter flushes and shuts down the stdouttrace exporter.
func ShutdownExporter(ctx context.Context, exp *stdouttrace.Exporter) error {
	if exp == nil {
		return fmt.Errorf("exporter cannot be nil")
	}
	return exp.Shutdown(ctx)
}

module sample

go 1.26.6

require go.opentelemetry.io/otel/exporters/stdout/stdouttrace 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/sdk 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/stdouttrace v1.43.0 h1:mS47AX77OtFfKG4vtp+84kuGSFZHTyxtXIN269vChY0=
go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.43.0/go.mod h1:PJnsC41lAGncJlPUniSwM81gc80GkgWJWr3cu2nKEtU=
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=
go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
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": "verify stdouttrace.Exporter.MarshalLog in pkg:golang/go.opentelemetry.io/otel/exporters/stdout/stdouttrace@v1.43.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/exporters/stdout/stdouttrace@v1.43.0"
  ],
  "symbols": [
    "stdouttrace.Exporter.MarshalLog"
  ]
}

package main

import (
	"context"
	"fmt"
	"os"
	"reflect"

	"sample"

	"go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
)

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

	// 1. stdouttrace.Exporter.MarshalLog returns structured logging metadata with Type stdout and WithTimestamps set to true by default
	expDefault, err := sample.CreateExporter()
	if err != nil {
		fmt.Fprintf(os.Stderr, "Contract failure: failed to create default exporter: %v\n", err)
		os.Exit(1)
	}
	if expDefault == nil {
		fmt.Fprintf(os.Stderr, "Contract failure: default exporter is nil\n")
		os.Exit(1)
	}

	defaultMeta, err := sample.GetLogMetadata(expDefault)
	if err != nil || defaultMeta == nil {
		fmt.Fprintf(os.Stderr, "Contract failure: GetLogMetadata returned error or nil: %v\n", err)
		os.Exit(1)
	}

	vDefault := reflect.ValueOf(defaultMeta)
	if vDefault.Kind() != reflect.Struct {
		fmt.Fprintf(os.Stderr, "Contract failure: expected struct from MarshalLog, got %v\n", vDefault.Kind())
		os.Exit(1)
	}

	typeFieldDefault := vDefault.FieldByName("Type")
	if !typeFieldDefault.IsValid() || typeFieldDefault.String() != "stdout" {
		fmt.Fprintf(os.Stderr, "Contract failure: expected Type 'stdout', got %v\n", typeFieldDefault)
		os.Exit(1)
	}

	tsFieldDefault := vDefault.FieldByName("WithTimestamps")
	if !tsFieldDefault.IsValid() || !tsFieldDefault.Bool() {
		fmt.Fprintf(os.Stderr, "Contract failure: expected WithTimestamps true by default, got %v\n", tsFieldDefault)
		os.Exit(1)
	}

	// 2. stdouttrace.Exporter.MarshalLog returns WithTimestamps set to false when configured with stdouttrace.WithoutTimestamps
	expWithoutTimestamps, err := sample.CreateExporter(stdouttrace.WithoutTimestamps())
	if err != nil {
		fmt.Fprintf(os.Stderr, "Contract failure: failed to create exporter without timestamps: %v\n", err)
		os.Exit(1)
	}
	if expWithoutTimestamps == nil {
		fmt.Fprintf(os.Stderr, "Contract failure: exporter without timestamps is nil\n")
		os.Exit(1)
	}

	noTsMeta, err := sample.GetLogMetadata(expWithoutTimestamps)
	if err != nil || noTsMeta == nil {
		fmt.Fprintf(os.Stderr, "Contract failure: GetLogMetadata without timestamps failed: %v\n", err)
		os.Exit(1)
	}

	vNoTs := reflect.ValueOf(noTsMeta)
	tsFieldNoTs := vNoTs.FieldByName("WithTimestamps")
	if !tsFieldNoTs.IsValid() || tsFieldNoTs.Bool() {
		fmt.Fprintf(os.Stderr, "Contract failure: expected WithTimestamps false when WithoutTimestamps used, got %v\n", tsFieldNoTs)
		os.Exit(1)
	}

	// 3. stdouttrace.Exporter.MarshalLog returns a valid non-nil logging structure
	if _, err := sample.GetLogMetadata(nil); err == nil {
		fmt.Fprintf(os.Stderr, "Contract failure: expected error when calling GetLogMetadata with nil exporter\n")
		os.Exit(1)
	}

	// 4. stdouttrace.Exporter shuts down cleanly after log inspection
	if err := sample.ShutdownExporter(ctx, expDefault); err != nil {
		fmt.Fprintf(os.Stderr, "Contract failure: failed to shutdown default exporter: %v\n", err)
		os.Exit(1)
	}
	if err := sample.ShutdownExporter(ctx, expWithoutTimestamps); err != nil {
		fmt.Fprintf(os.Stderr, "Contract failure: failed to shutdown configured exporter: %v\n", err)
		os.Exit(1)
	}

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