go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.71.0: NewHandler

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.NewHandler in pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.71.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.71.0
Demonstrate these symbols/APIs:
  - otelhttp.NewHandler

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:sha256:244d7a06777cad2c675d0f72227f7bd54067b28fd7b9d019678869a9e3e762d1","contract":["otelhttp.NewHandler wraps an http.Handler to create OpenTelemetry trace spans for incoming HTTP requests"],"goal":"verify otelhttp.NewHandler in pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.71.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.71.0"],"schemaVersion":1,"symbols":["otelhttp.NewHandler"]},"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/contrib/instrumentation/net/http/otelhttp@v0.71.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.71.0","symbols":["otelhttp.NewHandler"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.25.0

require (
	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.71.0
	go.opentelemetry.io/otel/sdk v1.46.0
	go.opentelemetry.io/otel/trace v1.46.0
)

require (
	github.com/cespare/xxhash/v2 v2.3.0 // indirect
	github.com/felixge/httpsnoop v1.1.0 // indirect
	github.com/go-logr/logr v1.4.4 // 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 v1.46.0 // indirect
	go.opentelemetry.io/otel/metric v1.46.0 // indirect
	golang.org/x/sys v0.47.0 // 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/felixge/httpsnoop v1.1.0 h1:3YtUj32ZZkqZtt3sZZsClsymw/QDuVfpNhoA31zeORc=
github.com/felixge/httpsnoop v1.1.0/go.mod h1:Zqxgdd+1Rkcz8euOqdr7lqgCRJztwr5hp9vDSi5UZCE=
github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
github.com/go-logr/logr v1.4.4 h1:tG4xh9yMsRCAiodLVTxyrkzSZ9+o0L1Kg/+cPVcbP/8=
github.com/go-logr/logr v1.4.4/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/stretchr/testify v1.12.1 h1:EuwCh5fleGS7H32xRwO3wRGT7DxrDhLAT6FF8MpWDWE=
github.com/stretchr/testify v1.12.1/go.mod h1:MDEgiDPPsNp5cuIrHPPCyornHKgEVbtFUmoNlxoYthg=
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 v0.71.0 h1:3g7B90UzBltIDKq1/5mrTGxTnOFDV0ICOhLoxiZ8jlg=
go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.71.0/go.mod h1:Ef8SuTh59BT7+ofpDxN9z+yOlc4t2GjLmKDgYNJL/NU=
go.opentelemetry.io/otel v1.46.0 h1:FHt5/CDyVxi/8IM1CH7VE/rRgq3kLHa2mSTVMO8AWyc=
go.opentelemetry.io/otel v1.46.0/go.mod h1:Gj3SEScelsNC45tp4nSxRYlS+f5iez7W8XPMCt905kE=
go.opentelemetry.io/otel/metric v1.46.0 h1:yBnkXvgV7AXFILZc5K6IZe/CBFF3OS7BJ8ov6/lj0K8=
go.opentelemetry.io/otel/metric v1.46.0/go.mod h1:iPmdWqifKUdzziPkvvzIJXITl56fQx2mGM/DHLB3/2o=
go.opentelemetry.io/otel/sdk v1.46.0 h1:h5CNQQjEbuQXY/JfZtgt3i7HVFV3aHPO2OAwO2eTYPI=
go.opentelemetry.io/otel/sdk v1.46.0/go.mod h1:GAERFXFt5SYCEB+YiKUbMBeza6UaDH7GmGOZEfh2gSM=
go.opentelemetry.io/otel/sdk/metric v1.46.0 h1:0piZ26EG4RBfebb2jhDH6ERCYHoVWduc3kLgPCwSnSE=
go.opentelemetry.io/otel/sdk/metric v1.46.0/go.mod h1:I1PbKrdVc8Qu8HYVDNtqVIwLwjNrhsV/uFuxfwg8mO4=
go.opentelemetry.io/otel/trace v1.46.0 h1:OULy7ccdJnZtJ0UDYFOIGaCmiWzJ8Vi2G/Rsu60qs1c=
go.opentelemetry.io/otel/trace v1.46.0/go.mod h1:J7GAXweO77XSFkB/rmAqk9D6ihszhFjLU+d9WuUxDLI=
go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
go.yaml.in/yaml/v3 v3.0.5 h1:N6y/pJk8buWs9NY5ERU2HSMfm+IuD/OtfdAnq6kESPw=
go.yaml.in/yaml/v3 v3.0.5/go.mod h1:HVTZu1O7/Vkt2N+BFy8Zza+lnLsABggaTM2ZpNIGuKg=
golang.org/x/sys v0.47.0 h1:o7XGOvZQCADBQQ4Y7VNq2dRWQR7JmOUW8Kxx4ZsNgWs=
golang.org/x/sys v0.47.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=

package main

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

	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
	"go.opentelemetry.io/otel/sdk/trace/tracetest"
	"go.opentelemetry.io/otel/trace"
)

func setupTracer() (*sdktrace.TracerProvider, *tracetest.InMemoryExporter) {
	exporter := tracetest.NewInMemoryExporter()
	tp := sdktrace.NewTracerProvider(
		sdktrace.WithSyncer(exporter),
	)
	return tp, exporter
}

func main() {
	tp, exporter := setupTracer()
	defer func() {
		_ = tp.Shutdown(context.Background())
	}()

	innerHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		span := trace.SpanFromContext(r.Context())
		if span.SpanContext().IsValid() {
			w.Header().Set("X-Trace-ID", span.SpanContext().TraceID().String())
		}
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte("Hello from instrumented handler"))
	})

	handler := otelhttp.NewHandler(
		innerHandler,
		"demo-handler",
		otelhttp.WithTracerProvider(tp),
	)

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

	fmt.Printf("Status: %d\n", rec.Code)
	fmt.Printf("Body: %s\n", rec.Body.String())
	fmt.Printf("Recorded %d span(s)\n", len(exporter.GetSpans()))
}

{
  "schemaVersion": 1,
  "goal": "verify otelhttp.NewHandler in pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.71.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp@v0.71.0"
  ],
  "symbols": [
    "otelhttp.NewHandler"
  ]
}

package main

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

	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
	"go.opentelemetry.io/otel/sdk/trace/tracetest"
	"go.opentelemetry.io/otel/trace"
)

func main() {
	exporter := tracetest.NewInMemoryExporter()
	tp := sdktrace.NewTracerProvider(
		sdktrace.WithSyncer(exporter),
	)
	defer func() {
		_ = tp.Shutdown(context.Background())
	}()

	// Contract: otelhttp.NewHandler wraps an http.Handler to create OpenTelemetry trace spans for incoming HTTP requests
	{
		exporter.Reset()
		innerHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			span := trace.SpanFromContext(r.Context())
			if !span.SpanContext().IsValid() {
				fmt.Fprintln(os.Stderr, "FAIL: expected valid span in request context")
				os.Exit(1)
			}
			w.WriteHeader(http.StatusOK)
			_, _ = w.Write([]byte("handler response"))
		})

		handler := otelhttp.NewHandler(innerHandler, "server-handler-operation", otelhttp.WithTracerProvider(tp))

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

		if rec.Code != http.StatusOK {
			fmt.Fprintf(os.Stderr, "FAIL: expected status 200, got %d\n", rec.Code)
			os.Exit(1)
		}
		if rec.Body.String() != "handler response" {
			fmt.Fprintf(os.Stderr, "FAIL: expected body 'handler response', got '%s'\n", rec.Body.String())
			os.Exit(1)
		}

		spans := exporter.GetSpans()
		if len(spans) != 1 {
			fmt.Fprintf(os.Stderr, "FAIL: expected 1 span, got %d\n", len(spans))
			os.Exit(1)
		}
		// Under otelhttp v0.71.0 default semantic conventions, the HTTP method is used as the span name
		if spans[0].Name != "GET" {
			fmt.Fprintf(os.Stderr, "FAIL: expected span name 'GET', got '%s'\n", spans[0].Name)
			os.Exit(1)
		}
	}

	fmt.Println("PASS: all contract assertions passed")
}