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

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.NewTransport 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.NewTransport

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:sha256:30efd53c3e6b4b1e19439752845caa4e82a94a894f31626a6d9090a02f92466c","contract":["otelhttp.NewTransport wraps an http.RoundTripper to create client trace spans for outgoing HTTP requests"],"goal":"verify otelhttp.NewTransport 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.NewTransport"]},"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.NewTransport"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.0

require (
	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.71.0
	go.opentelemetry.io/otel/sdk 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
	go.opentelemetry.io/otel/trace 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"
	"io"
	"net/http"
	"strings"
	"time"

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

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

func (m mockRoundTripper) RoundTrip(r *http.Request) (*http.Response, error) {
	return m(r)
}

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())
	}()

	mockRT := mockRoundTripper(func(r *http.Request) (*http.Response, error) {
		return &http.Response{
			StatusCode: http.StatusOK,
			Body:       io.NopCloser(strings.NewReader("client call ok")),
			Header:     make(http.Header),
		}, nil
	})

	clientTransport := otelhttp.NewTransport(
		mockRT,
		otelhttp.WithTracerProvider(tp),
	)
	client := &http.Client{
		Transport: clientTransport,
		Timeout:   5 * time.Second,
	}

	req, err := http.NewRequest(http.MethodGet, "http://example.com/api/resource", nil)
	if err != nil {
		fmt.Printf("Request creation failed: %v\n", err)
		return
	}

	resp, err := client.Do(req)
	if err != nil {
		fmt.Printf("Client request failed: %v\n", err)
		return
	}
	defer resp.Body.Close()

	body, _ := io.ReadAll(resp.Body)
	fmt.Printf("Response Status: %d, Body: %s\n", resp.StatusCode, string(body))

	spans := exporter.GetSpans()
	fmt.Printf("Recorded %d OpenTelemetry spans.\n", len(spans))
}

{
  "schemaVersion": 1,
  "goal": "verify otelhttp.NewTransport 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.NewTransport"
  ]
}

package main

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"os"
	"strings"

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

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

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

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

	// Contract 1: otelhttp.NewTransport wraps an http.RoundTripper to create client trace spans for outgoing HTTP requests
	{
		exporter.Reset()
		baseRT := roundTripperFunc(func(r *http.Request) (*http.Response, error) {
			return &http.Response{
				StatusCode: http.StatusOK,
				Body:       io.NopCloser(strings.NewReader("client response")),
				Header:     make(http.Header),
			}, nil
		})

		transport := otelhttp.NewTransport(baseRT, otelhttp.WithTracerProvider(tp))
		client := &http.Client{Transport: transport}

		req, err := http.NewRequest(http.MethodGet, "http://example.com/api/test", nil)
		if err != nil {
			fmt.Fprintf(os.Stderr, "FAIL: http.NewRequest failed: %v\n", err)
			os.Exit(1)
		}

		resp, err := client.Do(req)
		if err != nil {
			fmt.Fprintf(os.Stderr, "FAIL: client.Do failed: %v\n", err)
			os.Exit(1)
		}
		body, _ := io.ReadAll(resp.Body)
		_ = resp.Body.Close()

		if string(body) != "client response" {
			fmt.Fprintf(os.Stderr, "FAIL: expected body 'client response', got '%s'\n", string(body))
			os.Exit(1)
		}

		spans := exporter.GetSpans()
		if len(spans) != 1 {
			fmt.Fprintf(os.Stderr, "FAIL: expected 1 span from transport, got %d\n", len(spans))
			os.Exit(1)
		}
	}

	fmt.Println("PASS: otelhttp contracts verified")
}