go.opentelemetry.io/otel v1.38.0: GetErrorHandler, GetMeterProvider, GetTextMapPropagator

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 pkg:golang/go.opentelemetry.io/otel@v1.38.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel@v1.38.0
Demonstrate these symbols/APIs:
  - otel.GetErrorHandler
  - otel.GetMeterProvider
  - otel.GetTextMapPropagator
  - otel.GetTracerProvider
  - otel.Handle
  - otel.Meter
  - otel.SetErrorHandler
  - otel.SetMeterProvider
  - otel.SetTextMapPropagator
  - otel.SetTracerProvider
  - otel.Tracer
  - otel.Version

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:ecbdcdebdd99dd52b54ea7f1403028fd55e584646d42805434c825111987231d","contract":["otel.GetMeterProvider returns default non-nil MeterProvider and otel.SetMeterProvider updates the global MeterProvider","otel.Meter creates named Meter with options to construct synchronous (Int64Counter, Int64UpDownCounter, Float64Histogram) and asynchronous (Int64ObservableGauge) instruments","otel.GetTracerProvider returns default non-nil TracerProvider and otel.SetTracerProvider updates the global TracerProvider","otel.Tracer creates named Tracer capable of starting spans, adding events, and recording errors","otel.SetErrorHandler registers ErrorHandlerFunc to handle errors dispatched via otel.Handle safely and concurrently","otel.GetTextMapPropagator and otel.SetTextMapPropagator manage global composite text map propagators","otel.Version returns the active OpenTelemetry release version"],"goal":"verify pkg:golang/go.opentelemetry.io/otel@v1.38.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel@v1.38.0"],"schemaVersion":1,"symbols":["otel.GetErrorHandler","otel.GetMeterProvider","otel.GetTextMapPropagator","otel.GetTracerProvider","otel.Handle","otel.Meter","otel.SetErrorHandler","otel.SetMeterProvider","otel.SetTextMapPropagator","otel.SetTracerProvider","otel.Tracer","otel.Version"]},"contractCommand":["go","test","./..."],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","executionContext":"go","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","runtime":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/go.opentelemetry.io/otel@v1.38.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel@v1.38.0","symbols":["otel.GetErrorHandler","otel.GetMeterProvider","otel.GetTextMapPropagator","otel.GetTracerProvider","otel.Handle","otel.Meter","otel.SetErrorHandler","otel.SetMeterProvider","otel.SetTextMapPropagator","otel.SetTracerProvider","otel.Tracer","otel.Version"],"verifierAdapter":"golang@1"}

module sample

go 1.24

require (
	go.opentelemetry.io/otel v1.38.0
	go.opentelemetry.io/otel/metric v1.38.0
	go.opentelemetry.io/otel/trace v1.38.0
)

require (
	github.com/go-logr/logr v1.4.3 // indirect
	github.com/go-logr/stdr v1.2.2 // indirect
	go.opentelemetry.io/auto/sdk v1.1.0 // 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/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 v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
go.opentelemetry.io/otel v1.38.0 h1:RkfdswUDRimDg0m2Az18RKOsnI8UDzppJAtj01/Ymk8=
go.opentelemetry.io/otel v1.38.0/go.mod h1:zcmtmQ1+YmQM9wrNsTGV/q/uyusom3P8RxwExxkZhjM=
go.opentelemetry.io/otel/metric v1.38.0 h1:Kl6lzIYGAh5M159u9NgiRkmoMKjvbsKtYRwgfrA6WpA=
go.opentelemetry.io/otel/metric v1.38.0/go.mod h1:kB5n/QoRM8YwmUahxvI3bO34eVtQf2i4utNVLr9gEmI=
go.opentelemetry.io/otel/trace v1.38.0 h1:Fxk5bKrDZJUH+AMyyIXGcFAPah0oRcT+LuNtJrmcNLE=
go.opentelemetry.io/otel/trace v1.38.0/go.mod h1:j1P9ivuFsTceSWe1oY+EeW3sc+Pp42sO++GHkg4wwhs=
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"
	"strings"
	"sync"
	"sync/atomic"
	"testing"

	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/metric"
	noopmetric "go.opentelemetry.io/otel/metric/noop"
	"go.opentelemetry.io/otel/propagation"
	"go.opentelemetry.io/otel/trace"
	nooptrace "go.opentelemetry.io/otel/trace/noop"
)

func TestGlobalMeterProviderAndInstruments(t *testing.T) {
	origMP := otel.GetMeterProvider()
	defer otel.SetMeterProvider(origMP)

	mp := otel.GetMeterProvider()
	if mp == nil {
		t.Fatal("expected non-nil default MeterProvider")
	}

	meter := otel.Meter(
		"example.com/sample/meter",
		metric.WithInstrumentationVersion("v1.38.0"),
		metric.WithSchemaURL("https://opentelemetry.io/schemas/1.24.0"),
	)
	if meter == nil {
		t.Fatal("expected non-nil Meter")
	}

	ctx := context.Background()

	counter, err := meter.Int64Counter(
		"http_requests_total",
		metric.WithDescription("Total number of HTTP requests"),
		metric.WithUnit("{request}"),
	)
	if err != nil {
		t.Fatalf("unexpected error creating Int64Counter: %v", err)
	}
	counter.Add(ctx, 1, metric.WithAttributes(attribute.String("path", "/api/v1/resource")))

	upDownCounter, err := meter.Int64UpDownCounter(
		"active_connections",
		metric.WithDescription("Number of active connections"),
		metric.WithUnit("{connection}"),
	)
	if err != nil {
		t.Fatalf("unexpected error creating Int64UpDownCounter: %v", err)
	}
	upDownCounter.Add(ctx, 5)
	upDownCounter.Add(ctx, -2)

	histogram, err := meter.Float64Histogram(
		"request_duration_seconds",
		metric.WithDescription("Duration of HTTP requests in seconds"),
		metric.WithUnit("s"),
		metric.WithExplicitBucketBoundaries(0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0, 10.0),
	)
	if err != nil {
		t.Fatalf("unexpected error creating Float64Histogram: %v", err)
	}
	histogram.Record(ctx, 0.045, metric.WithAttributes(attribute.Int("status_code", 200)))

	var gaugeValue int64 = 42
	gauge, err := meter.Int64ObservableGauge(
		"system_memory_usage_bytes",
		metric.WithDescription("Current system memory usage"),
		metric.WithUnit("By"),
	)
	if err != nil {
		t.Fatalf("unexpected error creating Int64ObservableGauge: %v", err)
	}

	registration, err := meter.RegisterCallback(
		func(ctx context.Context, obs metric.Observer) error {
			obs.ObserveInt64(gauge, atomic.LoadInt64(&gaugeValue), metric.WithAttributes(attribute.String("pool", "heap")))
			return nil
		},
		gauge,
	)
	if err != nil {
		t.Fatalf("unexpected error registering callback: %v", err)
	}
	if err := registration.Unregister(); err != nil {
		t.Fatalf("unexpected error unregistering callback: %v", err)
	}

	customMP := noopmetric.NewMeterProvider()
	otel.SetMeterProvider(customMP)
	if otel.GetMeterProvider() != customMP {
		t.Fatal("expected GetMeterProvider to return registered custom MeterProvider")
	}
}

func TestGlobalTracerProviderAndTracer(t *testing.T) {
	origTP := otel.GetTracerProvider()
	defer otel.SetTracerProvider(origTP)

	tp := otel.GetTracerProvider()
	if tp == nil {
		t.Fatal("expected non-nil default TracerProvider")
	}

	tracer := otel.Tracer(
		"example.com/sample/tracer",
		trace.WithInstrumentationVersion("v1.38.0"),
		trace.WithSchemaURL("https://opentelemetry.io/schemas/1.24.0"),
	)
	if tracer == nil {
		t.Fatal("expected non-nil Tracer")
	}

	ctx := context.Background()
	ctx, span := tracer.Start(
		ctx,
		"operation_sample",
		trace.WithSpanKind(trace.SpanKindServer),
		trace.WithAttributes(attribute.String("service.name", "order-service")),
	)
	if span == nil {
		t.Fatal("expected non-nil Span")
	}
	span.AddEvent("cache_miss", trace.WithAttributes(attribute.String("key", "user:123")))
	span.RecordError(errors.New("transient database warning"))
	span.End()

	customTP := nooptrace.NewTracerProvider()
	otel.SetTracerProvider(customTP)
	if otel.GetTracerProvider() != customTP {
		t.Fatal("expected GetTracerProvider to return registered custom TracerProvider")
	}
}

func TestGlobalErrorHandler(t *testing.T) {
	origHandler := otel.GetErrorHandler()
	defer otel.SetErrorHandler(origHandler)

	if otel.GetErrorHandler() == nil {
		t.Fatal("expected non-nil default ErrorHandler")
	}

	var (
		mu         sync.Mutex
		seenErrors []error
	)
	customHandler := otel.ErrorHandlerFunc(func(err error) {
		mu.Lock()
		defer mu.Unlock()
		seenErrors = append(seenErrors, err)
	})
	otel.SetErrorHandler(customHandler)

	testErr1 := errors.New("simulated otel exporter failure")
	testErr2 := errors.New("simulated batch timeout")

	otel.Handle(testErr1)
	otel.Handle(testErr2)

	mu.Lock()
	if len(seenErrors) != 2 {
		t.Fatalf("expected 2 errors handled, got %d", len(seenErrors))
	}
	if seenErrors[0] != testErr1 || seenErrors[1] != testErr2 {
		t.Fatalf("unexpected error slice content: %v", seenErrors)
	}
	mu.Unlock()

	otel.Handle(nil)

	var wg sync.WaitGroup
	for i := 0; i < 50; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			otel.Handle(errors.New("concurrent error"))
		}()
	}
	wg.Wait()

	mu.Lock()
	if len(seenErrors) != 53 {
		t.Fatalf("expected 53 handled errors, got %d", len(seenErrors))
	}
	mu.Unlock()
}

func TestGlobalTextMapPropagator(t *testing.T) {
	origProp := otel.GetTextMapPropagator()
	defer otel.SetTextMapPropagator(origProp)

	if otel.GetTextMapPropagator() == nil {
		t.Fatal("expected non-nil default TextMapPropagator")
	}

	composite := propagation.NewCompositeTextMapPropagator(
		propagation.TraceContext{},
		propagation.Baggage{},
	)
	otel.SetTextMapPropagator(composite)

	carrier := propagation.MapCarrier{}
	ctx := context.Background()
	otel.GetTextMapPropagator().Inject(ctx, carrier)

	extractedCtx := otel.GetTextMapPropagator().Extract(context.Background(), carrier)
	if extractedCtx == nil {
		t.Fatal("expected non-nil extracted context")
	}
}

func TestVersion(t *testing.T) {
	v := otel.Version()
	if v == "" {
		t.Fatal("expected non-empty Version")
	}
	if !strings.Contains(v, "1.38.0") {
		t.Fatalf("expected version to contain 1.38.0, got %q", v)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/go.opentelemetry.io/otel@v1.38.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel@v1.38.0"
  ],
  "symbols": [
    "otel.GetErrorHandler",
    "otel.GetMeterProvider",
    "otel.GetTextMapPropagator",
    "otel.GetTracerProvider",
    "otel.Handle",
    "otel.Meter",
    "otel.SetErrorHandler",
    "otel.SetMeterProvider",
    "otel.SetTextMapPropagator",
    "otel.SetTracerProvider",
    "otel.Tracer",
    "otel.Version"
  ]
}