go.opentelemetry.io/otel/log v0.19.0: Logger

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/log.Logger in pkg:golang/go.opentelemetry.io/otel/log@v0.19.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel/log@v0.19.0
Demonstrate these symbols/APIs:
  - go.opentelemetry.io/otel/log.Logger
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:sha256:7a33f4479e49aaa24f18e5de043ff4d9f9c24d6b35a3f751a5ec3febf1331527","contract":["Logger Config returns configured instrumentation scope name and options","Logger Enabled checks severity against configured threshold","Logger Emit captures structured log records with timestamp, severity, body, and attributes","Logger Emit handles concurrent log emissions safely"],"goal":"verify go.opentelemetry.io/otel/log.Logger in pkg:golang/go.opentelemetry.io/otel/log@v0.19.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/log@v0.19.0"],"schemaVersion":1,"symbols":["go.opentelemetry.io/otel/log.Logger"]},"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/log@v0.19.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/log@v0.19.0","symbols":["go.opentelemetry.io/otel/log.Logger"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require (
	go.opentelemetry.io/otel v1.43.0
	go.opentelemetry.io/otel/log v0.19.0
)

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
	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
	go.opentelemetry.io/otel/metric v1.43.0 // indirect
	go.opentelemetry.io/otel/trace v1.43.0 // 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/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/log v0.19.0 h1:KUZs/GOsw79TBBMfDWsXS+KZ4g2Ckzksd1ymzsIEbo4=
go.opentelemetry.io/otel/log v0.19.0/go.mod h1:5DQYeGmxVIr4n0/BcJvF4upsraHjg6vudJJpnkL6Ipk=
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/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=
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"
	"sync"

	"go.opentelemetry.io/otel/log"
	"go.opentelemetry.io/otel/log/embedded"
)

// InMemoryLogger implements log.Logger and captures emitted log records in memory.
type InMemoryLogger struct {
	embedded.Logger
	name        string
	config      log.LoggerConfig
	minSeverity log.Severity
	mu          sync.Mutex
	records     []log.Record
}

// NewInMemoryLogger creates a new InMemoryLogger.
func NewInMemoryLogger(name string, options ...log.LoggerOption) *InMemoryLogger {
	cfg := log.NewLoggerConfig(options...)
	return &InMemoryLogger{
		name:        name,
		config:      cfg,
		minSeverity: log.SeverityInfo,
	}
}

// Name returns the instrumentation scope name.
func (l *InMemoryLogger) Name() string {
	return l.name
}

// Config returns the configured LoggerConfig.
func (l *InMemoryLogger) Config() log.LoggerConfig {
	return l.config
}

// Emit captures the given log record thread-safely.
func (l *InMemoryLogger) Emit(ctx context.Context, record log.Record) {
	l.mu.Lock()
	defer l.mu.Unlock()
	l.records = append(l.records, record.Clone())
}

// Enabled checks if the record severity meets the minimum severity threshold.
func (l *InMemoryLogger) Enabled(ctx context.Context, param log.EnabledParameters) bool {
	if param.Severity != log.SeverityUndefined && param.Severity < l.minSeverity {
		return false
	}
	return true
}

// SetMinSeverity updates the minimum severity threshold.
func (l *InMemoryLogger) SetMinSeverity(sev log.Severity) {
	l.mu.Lock()
	defer l.mu.Unlock()
	l.minSeverity = sev
}

// Records returns a copy of all captured log records.
func (l *InMemoryLogger) Records() []log.Record {
	l.mu.Lock()
	defer l.mu.Unlock()
	copied := make([]log.Record, len(l.records))
	copy(copied, l.records)
	return copied
}

{
  "schemaVersion": 1,
  "goal": "verify go.opentelemetry.io/otel/log.Logger in pkg:golang/go.opentelemetry.io/otel/log@v0.19.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/log@v0.19.0"
  ],
  "symbols": [
    "go.opentelemetry.io/otel/log.Logger"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package main

import (
	"context"
	"fmt"
	"os"
	"sync"
	"time"

	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/log"
	"sample"
)

func main() {
	// 1. Logger Config returns configured instrumentation scope name and options
	scopeName := "example.com/app/auth"
	logger := sample.NewInMemoryLogger(
		scopeName,
		log.WithInstrumentationVersion("1.0.0"),
		log.WithSchemaURL("https://opentelemetry.io/schemas/1.24.0"),
		log.WithInstrumentationAttributes(attribute.String("service.name", "auth-service")),
	)

	if logger.Name() != scopeName {
		fmt.Fprintf(os.Stderr, "expected logger name %q, got %q\n", scopeName, logger.Name())
		os.Exit(1)
	}

	cfg := logger.Config()
	if cfg.InstrumentationVersion() != "1.0.0" {
		fmt.Fprintf(os.Stderr, "expected version 1.0.0, got %s\n", cfg.InstrumentationVersion())
		os.Exit(1)
	}
	if cfg.SchemaURL() != "https://opentelemetry.io/schemas/1.24.0" {
		fmt.Fprintf(os.Stderr, "expected schema url https://opentelemetry.io/schemas/1.24.0, got %s\n", cfg.SchemaURL())
		os.Exit(1)
	}
	attrs := cfg.InstrumentationAttributes()
	attrVal, hasAttr := attrs.Value("service.name")
	if !hasAttr || attrVal.AsString() != "auth-service" {
		fmt.Fprintf(os.Stderr, "expected instrumentation attribute service.name=auth-service\n")
		os.Exit(1)
	}

	// 2. Logger Enabled checks severity against configured threshold
	ctx := context.Background()
	logger.SetMinSeverity(log.SeverityInfo)

	if logger.Enabled(ctx, log.EnabledParameters{Severity: log.SeverityDebug}) {
		fmt.Fprintf(os.Stderr, "expected Enabled to return false for SeverityDebug when min is Info\n")
		os.Exit(1)
	}
	if !logger.Enabled(ctx, log.EnabledParameters{Severity: log.SeverityInfo}) {
		fmt.Fprintf(os.Stderr, "expected Enabled to return true for SeverityInfo\n")
		os.Exit(1)
	}
	if !logger.Enabled(ctx, log.EnabledParameters{Severity: log.SeverityError}) {
		fmt.Fprintf(os.Stderr, "expected Enabled to return true for SeverityError\n")
		os.Exit(1)
	}

	// 3. Logger Emit captures structured log records with timestamp, severity, body, and attributes
	var loggerInterface log.Logger = logger
	now := time.Date(2026, 8, 28, 12, 0, 0, 0, time.UTC)
	var rec log.Record
	rec.SetTimestamp(now)
	rec.SetSeverity(log.SeverityInfo)
	rec.SetSeverityText("INFO")
	rec.SetBody(log.StringValue("user login successful"))
	rec.AddAttributes(
		log.String("user.id", "usr-123"),
		log.Int("attempts", 1),
	)

	loggerInterface.Emit(ctx, rec)

	records := logger.Records()
	if len(records) != 1 {
		fmt.Fprintf(os.Stderr, "expected 1 record, got %d\n", len(records))
		os.Exit(1)
	}

	captured := records[0]
	if !captured.Timestamp().Equal(now) {
		fmt.Fprintf(os.Stderr, "expected timestamp %v, got %v\n", now, captured.Timestamp())
		os.Exit(1)
	}
	if captured.Severity() != log.SeverityInfo {
		fmt.Fprintf(os.Stderr, "expected severity INFO, got %v\n", captured.Severity())
		os.Exit(1)
	}
	if captured.Body().AsString() != "user login successful" {
		fmt.Fprintf(os.Stderr, "expected body 'user login successful', got %s\n", captured.Body().AsString())
		os.Exit(1)
	}
	if captured.AttributesLen() != 2 {
		fmt.Fprintf(os.Stderr, "expected 2 attributes, got %d\n", captured.AttributesLen())
		os.Exit(1)
	}

	// 4. Logger Emit handles concurrent log emissions safely
	var wg sync.WaitGroup
	for i := 0; i < 20; i++ {
		wg.Add(1)
		go func(idx int) {
			defer wg.Done()
			var r log.Record
			r.SetSeverity(log.SeverityWarn)
			r.SetBody(log.IntValue(idx))
			loggerInterface.Emit(ctx, r)
		}(i)
	}
	wg.Wait()

	if len(logger.Records()) != 21 {
		fmt.Fprintf(os.Stderr, "expected 21 total records, got %d\n", len(logger.Records()))
		os.Exit(1)
	}
}