go.opentelemetry.io/otel/trace v1.37.0: Tracer

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/trace.Tracer in pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0
Kind: HOW

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

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:sha256:8fd84c2dd486e4bbd72fff2e4c7c945e5df60f3541b2f71ee7057765b0ba97c3","contract":["noop.NewTracerProvider returns a TracerProvider whose Tracer method produces a non-nil trace.Tracer","Tracer.Start returns a non-nil Span and a context containing that Span via SpanFromContext","Tracer.Start accepts SpanStartOptions including WithSpanKind, WithAttributes, and WithLinks","Tracer.Start with WithNewRoot creates a root span even when the parent context contains an existing span","Span operations including SetStatus, SetAttributes, AddEvent, AddLink, RecordError, SetName, and End execute safely"],"goal":"verify go.opentelemetry.io/otel/trace.Tracer in pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0"],"schemaVersion":1,"symbols":["go.opentelemetry.io/otel/trace.Tracer"]},"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/trace@v1.37.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0","symbols":["go.opentelemetry.io/otel/trace.Tracer"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require (
	go.opentelemetry.io/otel v1.37.0
	go.opentelemetry.io/otel/trace v1.37.0
)

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 v1.4.3 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 v1.10.0 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/trace v1.37.0 h1:HLdcFNbRQBE2imdSEgm/kwqmQj1Or1l/7bW6mxVK7z4=
go.opentelemetry.io/otel/trace v1.37.0/go.mod h1:TlgrlQ+PtQO5XFerSPUYG0JSgGyryXewPGyayAWSBS0=
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"

	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/codes"
	"go.opentelemetry.io/otel/trace"
	"go.opentelemetry.io/otel/trace/noop"
)

// TracedWorker executes operations instrumented with an OpenTelemetry Tracer.
type TracedWorker struct {
	tracer trace.Tracer
}

// NewTracedWorker returns a TracedWorker instrumented with the given Tracer.
// If tracer is nil, it falls back to a Tracer from noop.NewTracerProvider.
func NewTracedWorker(tracer trace.Tracer) *TracedWorker {
	if tracer == nil {
		tp := noop.NewTracerProvider()
		tracer = tp.Tracer("sample-worker")
	}
	return &TracedWorker{
		tracer: tracer,
	}
}

// Tracer returns the underlying trace.Tracer.
func (w *TracedWorker) Tracer() trace.Tracer {
	return w.tracer
}

// ProcessTask runs a traced unit of work, recording attributes and handling errors.
func (w *TracedWorker) ProcessTask(ctx context.Context, taskID string, succeed bool) (context.Context, error) {
	ctx, span := w.tracer.Start(ctx, "process_task",
		trace.WithSpanKind(trace.SpanKindInternal),
		trace.WithAttributes(attribute.String("task.id", taskID)),
	)
	defer span.End()

	span.AddEvent("task_started")

	if !succeed {
		err := errors.New("task processing failed")
		span.RecordError(err)
		span.SetStatus(codes.Error, err.Error())
		return ctx, err
	}

	span.SetAttributes(attribute.String("task.result", "success"))
	span.SetStatus(codes.Ok, "task completed successfully")
	span.AddEvent("task_finished")
	return ctx, nil
}

// ProcessSubTask starts a child span or a separate root span under the given context.
func (w *TracedWorker) ProcessSubTask(ctx context.Context, subTaskID string, newRoot bool) (context.Context, trace.Span) {
	opts := []trace.SpanStartOption{
		trace.WithAttributes(attribute.String("subtask.id", subTaskID)),
	}
	if newRoot {
		opts = append(opts, trace.WithNewRoot())
	}

	childCtx, span := w.tracer.Start(ctx, "process_subtask", opts...)
	return childCtx, span
}

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

package main

import (
	"context"
	"fmt"
	"os"

	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/codes"
	"go.opentelemetry.io/otel/trace"
	"go.opentelemetry.io/otel/trace/noop"
	"sample"
)

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

	// 1. noop.NewTracerProvider returns a TracerProvider whose Tracer method produces a non-nil trace.Tracer
	tp := noop.NewTracerProvider()
	var provider trace.TracerProvider = tp
	if provider == nil {
		fmt.Fprintf(os.Stderr, "noop.NewTracerProvider returned nil TracerProvider interface\n")
		os.Exit(1)
	}

	tracer := tp.Tracer("contract-test-tracer", trace.WithInstrumentationVersion("1.0.0"))
	var tracerIface trace.Tracer = tracer
	if tracerIface == nil {
		fmt.Fprintf(os.Stderr, "Tracer() returned nil trace.Tracer\n")
		os.Exit(1)
	}

	// 2. Tracer.Start returns a non-nil Span and a context containing that Span via SpanFromContext
	ctxSpan, span := tracer.Start(ctx, "root-operation")
	if span == nil {
		fmt.Fprintf(os.Stderr, "tracer.Start returned nil Span\n")
		os.Exit(1)
	}
	extractedSpan := trace.SpanFromContext(ctxSpan)
	if extractedSpan == nil {
		fmt.Fprintf(os.Stderr, "trace.SpanFromContext returned nil\n")
		os.Exit(1)
	}

	// 3. Tracer.Start accepts SpanStartOptions including WithSpanKind, WithAttributes, and WithLinks
	sampleLink := trace.Link{
		SpanContext: span.SpanContext(),
		Attributes: []attribute.KeyValue{
			attribute.String("link.type", "parent"),
		},
	}
	ctxOpt, spanOpt := tracer.Start(ctx, "options-operation",
		trace.WithSpanKind(trace.SpanKindClient),
		trace.WithAttributes(attribute.String("test.key", "test.value"), attribute.Int("test.count", 42)),
		trace.WithLinks(sampleLink),
	)
	if spanOpt == nil || ctxOpt == nil {
		fmt.Fprintf(os.Stderr, "tracer.Start with options returned nil span or context\n")
		os.Exit(1)
	}
	spanOpt.End()

	// 4. Tracer.Start with WithNewRoot creates a root span even when the parent context contains an existing span
	ctxWithParent, parentSpan := tracer.Start(ctx, "parent-span")
	defer parentSpan.End()

	_, rootSpan := tracer.Start(ctxWithParent, "independent-root", trace.WithNewRoot())
	if rootSpan == nil {
		fmt.Fprintf(os.Stderr, "tracer.Start with WithNewRoot returned nil span\n")
		os.Exit(1)
	}
	rootSpan.End()

	// 5. Span operations including SetStatus, SetAttributes, AddEvent, AddLink, RecordError, SetName, and End execute safely
	span.SetName("renamed-operation")
	span.SetAttributes(
		attribute.Bool("completed", true),
		attribute.Float64("score", 98.6),
	)
	span.SetStatus(codes.Ok, "operation complete")
	span.AddEvent("checkpoint", trace.WithAttributes(attribute.String("step", "validation")))
	span.AddLink(sampleLink)
	span.RecordError(fmt.Errorf("synthetic validation error"))
	_ = span.IsRecording()
	_ = span.SpanContext()
	span.End()

	// 6. Verify integration with sample.TracedWorker helper
	worker := sample.NewTracedWorker(tracer)
	if worker == nil || worker.Tracer() == nil {
		fmt.Fprintf(os.Stderr, "NewTracedWorker initialization failed\n")
		os.Exit(1)
	}

	// Process task successfully
	taskCtx, err := worker.ProcessTask(ctx, "task-1", true)
	if err != nil || taskCtx == nil {
		fmt.Fprintf(os.Stderr, "ProcessTask (success) failed: %v\n", err)
		os.Exit(1)
	}

	// Process task with failure handling
	_, err = worker.ProcessTask(ctx, "task-2", false)
	if err == nil {
		fmt.Fprintf(os.Stderr, "ProcessTask (failure) expected error but got nil\n")
		os.Exit(1)
	}

	// Process subtasks with child and root configurations
	subCtx, subSpan := worker.ProcessSubTask(ctx, "subtask-child", false)
	if subSpan == nil || subCtx == nil {
		fmt.Fprintf(os.Stderr, "ProcessSubTask child failed\n")
		os.Exit(1)
	}
	subSpan.End()

	subRootCtx, subRootSpan := worker.ProcessSubTask(ctx, "subtask-root", true)
	if subRootSpan == nil || subRootCtx == nil {
		fmt.Fprintf(os.Stderr, "ProcessSubTask root failed\n")
		os.Exit(1)
	}
	subRootSpan.End()

	// Default initialization with nil tracer
	defaultWorker := sample.NewTracedWorker(nil)
	if defaultWorker == nil || defaultWorker.Tracer() == nil {
		fmt.Fprintf(os.Stderr, "defaultWorker initialization failed\n")
		os.Exit(1)
	}

	fmt.Println("All go.opentelemetry.io/otel/trace.Tracer contract assertions passed.")
}