go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.68.0: WithPropagators

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 otelhttp.WithPropagators in pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.68.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.68.0
Demonstrate these symbols/APIs:
  - otelhttp.WithPropagators

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:a3d92d1b72d7421e3792dcb83a7cd6d05fe2eb3e29dd8996e0577d8ad278916d","contract":["otelhttp.WithPropagators configures TextMapPropagator for HTTP handler inbound trace and baggage extraction","otelhttp.WithPropagators configures TextMapPropagator for HTTP transport outbound trace and baggage injection","otelhttp.WithPropagators with nil propagator preserves default propagator without panic"],"goal":"verify otelhttp.WithPropagators in pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.68.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.68.0"],"schemaVersion":1,"symbols":["otelhttp.WithPropagators"]},"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/contrib/instrumentation/net/http/otelhttp@v0.68.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.68.0","symbols":["otelhttp.WithPropagators"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require (
	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.68.0
	go.opentelemetry.io/otel v1.43.0
	go.opentelemetry.io/otel/trace v1.43.0
)

require (
	github.com/cespare/xxhash/v2 v2.3.0 // indirect
	github.com/felixge/httpsnoop v1.0.4 // 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
)

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/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
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/contrib/instrumentation/net/http/otelhttp v0.68.0 h1:CqXxU8VOmDefoh0+ztfGaymYbhdB/tT3zs79QaZTNGY=
go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.68.0/go.mod h1:BuhAPThV8PBHBvg8ZzZ/Ok3idOdhWIodywz2xEcRbJo=
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/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=

package main

import (
	"context"
	"fmt"
	"net/http"
	"net/http/httptest"

	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
	"go.opentelemetry.io/otel/propagation"
)

func main() {
	propagator := propagation.NewCompositeTextMapPropagator(
		propagation.TraceContext{},
		propagation.Baggage{},
	)

	// Configure HTTP handler with custom propagators
	handler := otelhttp.NewHandler(
		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			w.WriteHeader(http.StatusOK)
			_, _ = w.Write([]byte("propagator configured"))
		}),
		"example-operation",
		otelhttp.WithPropagators(propagator),
	)

	// Configure HTTP transport with custom propagators
	transport := otelhttp.NewTransport(
		http.DefaultTransport,
		otelhttp.WithPropagators(propagator),
	)

	req := httptest.NewRequest(http.MethodGet, "http://localhost/example", nil)
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	_ = transport
	_ = context.Background()
	fmt.Println("otelhttp.WithPropagators configured successfully")
}

{
  "schemaVersion": 1,
  "goal": "verify otelhttp.WithPropagators in pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.68.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.68.0"
  ],
  "symbols": [
    "otelhttp.WithPropagators"
  ]
}

package main

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"os"

	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
	"go.opentelemetry.io/otel/baggage"
	"go.opentelemetry.io/otel/propagation"
	"go.opentelemetry.io/otel/trace"
)

type contextKey string

const (
	testTraceKey   contextKey = "test-trace-id"
	testBaggageKey contextKey = "test-baggage-key"
)

// testPropagator demonstrates a custom TextMapPropagator injected/extracted by otelhttp.
type testPropagator struct{}

func (p testPropagator) Inject(ctx context.Context, carrier propagation.TextMapCarrier) {
	if val, ok := ctx.Value(testTraceKey).(string); ok && val != "" {
		carrier.Set("x-test-trace", val)
	}
	if val, ok := ctx.Value(testBaggageKey).(string); ok && val != "" {
		carrier.Set("x-test-baggage", val)
	}
}

func (p testPropagator) Extract(ctx context.Context, carrier propagation.TextMapCarrier) context.Context {
	if val := carrier.Get("x-test-trace"); val != "" {
		ctx = context.WithValue(ctx, testTraceKey, val)
	}
	if val := carrier.Get("x-test-baggage"); val != "" {
		ctx = context.WithValue(ctx, testBaggageKey, val)
	}
	return ctx
}

func (p testPropagator) Fields() []string {
	return []string{"x-test-trace", "x-test-baggage"}
}

type roundTripperFunc func(*http.Request) (*http.Response, error)

func (f roundTripperFunc) RoundTrip(r *http.Request) (*http.Response, error) {
	return f(r)
}

func main() {
	if err := runContractTests(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract test failure: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All contract assertions passed successfully.")
}

func runContractTests() error {
	compositePropagator := propagation.NewCompositeTextMapPropagator(
		propagation.TraceContext{},
		propagation.Baggage{},
		testPropagator{},
	)

	// Assertion 1: otelhttp.WithPropagators configures TextMapPropagator for HTTP handler inbound trace and baggage extraction
	if err := testHandlerInbound(compositePropagator); err != nil {
		return fmt.Errorf("handler inbound test failed: %w", err)
	}

	// Assertion 2: otelhttp.WithPropagators configures TextMapPropagator for HTTP transport outbound trace and baggage injection
	if err := testTransportOutbound(compositePropagator); err != nil {
		return fmt.Errorf("transport outbound test failed: %w", err)
	}

	// Assertion 3: otelhttp.WithPropagators with nil propagator preserves default propagator without panic
	if err := testNilPropagator(); err != nil {
		return fmt.Errorf("nil propagator test failed: %w", err)
	}

	return nil
}

func testHandlerInbound(prop propagation.TextMapPropagator) error {
	var extractedTrace string
	var extractedBaggage string
	var extractedW3CTraceID string
	var extractedW3CBaggage string

	innerHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if v, ok := r.Context().Value(testTraceKey).(string); ok {
			extractedTrace = v
		}
		if v, ok := r.Context().Value(testBaggageKey).(string); ok {
			extractedBaggage = v
		}

		sc := trace.SpanContextFromContext(r.Context())
		if sc.IsValid() {
			extractedW3CTraceID = sc.TraceID().String()
		}

		bag := baggage.FromContext(r.Context())
		extractedW3CBaggage = bag.Member("role").Value()

		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte("OK"))
	})

	handler := otelhttp.NewHandler(
		innerHandler,
		"test-handler-op",
		otelhttp.WithPropagators(prop),
	)

	req := httptest.NewRequest(http.MethodGet, "http://localhost/test", nil)
	req.Header.Set("x-test-trace", "trace-abc-123")
	req.Header.Set("x-test-baggage", "baggage-xyz-789")
	req.Header.Set("traceparent", "00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01")
	req.Header.Set("baggage", "role=admin")

	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		return fmt.Errorf("handler returned status %d, want 200", rec.Code)
	}
	if extractedTrace != "trace-abc-123" {
		return fmt.Errorf("extracted custom trace mismatch: got %q, want %q", extractedTrace, "trace-abc-123")
	}
	if extractedBaggage != "baggage-xyz-789" {
		return fmt.Errorf("extracted custom baggage mismatch: got %q, want %q", extractedBaggage, "baggage-xyz-789")
	}
	if extractedW3CTraceID != "4bf92f3577b34da6a3ce929d0e0e4736" {
		return fmt.Errorf("extracted W3C trace ID mismatch: got %q, want %q", extractedW3CTraceID, "4bf92f3577b34da6a3ce929d0e0e4736")
	}
	if extractedW3CBaggage != "admin" {
		return fmt.Errorf("extracted W3C baggage mismatch: got %q, want %q", extractedW3CBaggage, "admin")
	}

	return nil
}

func testTransportOutbound(prop propagation.TextMapPropagator) error {
	var capturedCustomTrace string
	var capturedCustomBaggage string
	var capturedW3CBaggage string

	mockRT := roundTripperFunc(func(r *http.Request) (*http.Response, error) {
		capturedCustomTrace = r.Header.Get("x-test-trace")
		capturedCustomBaggage = r.Header.Get("x-test-baggage")
		capturedW3CBaggage = r.Header.Get("baggage")
		return &http.Response{
			StatusCode: http.StatusOK,
			Header:     make(http.Header),
			Body:       io.NopCloser(bytes.NewReader([]byte("transport-ok"))),
		}, nil
	})

	transport := otelhttp.NewTransport(
		mockRT,
		otelhttp.WithPropagators(prop),
	)

	ctx := context.Background()
	ctx = context.WithValue(ctx, testTraceKey, "out-trace-555")
	ctx = context.WithValue(ctx, testBaggageKey, "out-baggage-666")
	bMember, err := baggage.NewMember("tenant", "acme")
	if err != nil {
		return fmt.Errorf("failed to create baggage member: %w", err)
	}
	bag, err := baggage.New(bMember)
	if err != nil {
		return fmt.Errorf("failed to create baggage: %w", err)
	}
	ctx = baggage.ContextWithBaggage(ctx, bag)

	outReq, err := http.NewRequestWithContext(ctx, http.MethodGet, "http://localhost/outbound", nil)
	if err != nil {
		return fmt.Errorf("failed to create outbound request: %w", err)
	}

	resp, err := transport.RoundTrip(outReq)
	if err != nil {
		return fmt.Errorf("transport RoundTrip failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("transport returned status %d, want 200", resp.StatusCode)
	}
	if capturedCustomTrace != "out-trace-555" {
		return fmt.Errorf("captured custom trace mismatch: got %q, want %q", capturedCustomTrace, "out-trace-555")
	}
	if capturedCustomBaggage != "out-baggage-666" {
		return fmt.Errorf("captured custom baggage mismatch: got %q, want %q", capturedCustomBaggage, "out-baggage-666")
	}
	if capturedW3CBaggage != "tenant=acme" {
		return fmt.Errorf("captured W3C baggage mismatch: got %q, want %q", capturedW3CBaggage, "tenant=acme")
	}

	return nil
}

func testNilPropagator() error {
	nilPropOpt := otelhttp.WithPropagators(nil)
	if nilPropOpt == nil {
		return fmt.Errorf("WithPropagators(nil) returned nil option")
	}

	var defaultHandlerInvoked bool
	defaultInner := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defaultHandlerInvoked = true
		w.WriteHeader(http.StatusOK)
	})

	nilHandler := otelhttp.NewHandler(defaultInner, "default-op", nilPropOpt)
	nilReq := httptest.NewRequest(http.MethodGet, "http://localhost/nil-test", nil)
	nilRec := httptest.NewRecorder()
	nilHandler.ServeHTTP(nilRec, nilReq)

	if !defaultHandlerInvoked || nilRec.Code != http.StatusOK {
		return fmt.Errorf("handler with nil propagator option failed to execute properly")
	}

	return nil
}