go.opentelemetry.io/contrib/detectors/gcp v1.39.0: NewDetector

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/contrib/detectors/gcp.NewDetector in pkg:golang/go.opentelemetry.io/contrib/detectors/gcp@v1.39.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/contrib/detectors/gcp@v1.39.0
Demonstrate these symbols/APIs:
  - go.opentelemetry.io/contrib/detectors/gcp.NewDetector

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:sha256:407948af89fd9b7eead5abf08ba6ccec5c185c1bf5288721066b422d50f09715","contract":["gcp.NewDetector returns a non-nil resource.Detector implementation","Detector.Detect on GCE populates cloud, host, and gcp.gce.instance attributes from metadata","Detector.Detect on Cloud Run populates cloud_run platform and faas.* resource attributes","resource.WithDetectors(gcp.NewDetector()) integrates with OpenTelemetry SDK resource.New"],"goal":"verify go.opentelemetry.io/contrib/detectors/gcp.NewDetector in pkg:golang/go.opentelemetry.io/contrib/detectors/gcp@v1.39.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/contrib/detectors/gcp@v1.39.0"],"schemaVersion":1,"symbols":["go.opentelemetry.io/contrib/detectors/gcp.NewDetector"]},"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/detectors/gcp@v1.39.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/contrib/detectors/gcp@v1.39.0","symbols":["go.opentelemetry.io/contrib/detectors/gcp.NewDetector"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require (
	go.opentelemetry.io/contrib/detectors/gcp v1.39.0
	go.opentelemetry.io/otel v1.39.0
	go.opentelemetry.io/otel/sdk v1.39.0
)

require (
	cloud.google.com/go/compute/metadata v0.9.0 // indirect
	github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.30.0 // indirect
	github.com/cespare/xxhash/v2 v2.3.0 // indirect
	github.com/go-logr/logr v1.4.3 // 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/metric v1.39.0 // indirect
	go.opentelemetry.io/otel/trace v1.39.0 // indirect
	golang.org/x/sys v0.39.0 // indirect
)

cloud.google.com/go/compute/metadata v0.9.0 h1:pDUj4QMoPejqq20dK0Pg2N4yG9zIkYGdBtwLoEkH9Zs=
cloud.google.com/go/compute/metadata v0.9.0/go.mod h1:E0bWwX5wTnLPedCKqk3pJmVgCBSM6qQI1yTBdEb3C10=
github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.30.0 h1:sBEjpZlNHzK1voKq9695PJSX2o5NEXl7/OL3coiIY0c=
github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.30.0/go.mod h1:P4WPRUkOhJC13W//jWpyfJNDAIpvRbAUIYLX/4jtlE0=
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 v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/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/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 v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRIccs7FGNTlIRMkT8wgtp5eCXdBlqhYGL6U=
github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/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/detectors/gcp v1.39.0 h1:kWRNZMsfBHZ+uHjiH4y7Etn2FK26LAGkNFw7RHv1DhE=
go.opentelemetry.io/contrib/detectors/gcp v1.39.0/go.mod h1:t/OGqzHBa5v6RHZwrDBJ2OirWc+4q/w2fTbLZwAKjTk=
go.opentelemetry.io/otel v1.39.0 h1:8yPrr/S0ND9QEfTfdP9V+SiwT4E0G7Y5MO7p85nis48=
go.opentelemetry.io/otel v1.39.0/go.mod h1:kLlFTywNWrFyEdH0oj2xK0bFYZtHRYUdv1NklR/tgc8=
go.opentelemetry.io/otel/metric v1.39.0 h1:d1UzonvEZriVfpNKEVmHXbdf909uGTOQjA0HF0Ls5Q0=
go.opentelemetry.io/otel/metric v1.39.0/go.mod h1:jrZSWL33sD7bBxg1xjrqyDjnuzTUB0x1nBERXd7Ftcs=
go.opentelemetry.io/otel/sdk v1.39.0 h1:nMLYcjVsvdui1B/4FRkwjzoRVsMK8uL/cj0OyhKzt18=
go.opentelemetry.io/otel/sdk v1.39.0/go.mod h1:vDojkC4/jsTJsE+kh+LXYQlbL8CgrEcwmt1ENZszdJE=
go.opentelemetry.io/otel/trace v1.39.0 h1:2d2vfpEDmCJ5zVYz7ijaJdOF59xLomrvj7bjt6/qCJI=
go.opentelemetry.io/otel/trace v1.39.0/go.mod h1:88w4/PnZSazkGzz/w84VHpQafiU4EtqqlVdxWy+rNOA=
golang.org/x/sys v0.39.0 h1:CvCKL8MeisomCi6qNZ+wbb0DN9E5AATixKsvNtMoMFk=
golang.org/x/sys v0.39.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
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"

	"go.opentelemetry.io/contrib/detectors/gcp"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/sdk/resource"
)

// NewGCPResourceDetector returns a resource.Detector configured via gcp.NewDetector.
func NewGCPResourceDetector() resource.Detector {
	return gcp.NewDetector()
}

// DetectGCPResource detects OpenTelemetry resource attributes using gcp.NewDetector
// and returns the resulting Resource and its attribute map.
func DetectGCPResource(ctx context.Context) (*resource.Resource, map[string]string, error) {
	detector := gcp.NewDetector()
	res, err := detector.Detect(ctx)
	if err != nil {
		return nil, nil, err
	}
	attrs := make(map[string]string)
	if res != nil {
		for _, kv := range res.Attributes() {
			if kv.Value.Type() == attribute.STRING {
				attrs[string(kv.Key)] = kv.Value.AsString()
			}
		}
	}
	return res, attrs, nil
}

{
  "schemaVersion": 1,
  "goal": "verify go.opentelemetry.io/contrib/detectors/gcp.NewDetector in pkg:golang/go.opentelemetry.io/contrib/detectors/gcp@v1.39.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/contrib/detectors/gcp@v1.39.0"
  ],
  "symbols": [
    "go.opentelemetry.io/contrib/detectors/gcp.NewDetector"
  ]
}

package main

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

	"example.com/sample"
	"go.opentelemetry.io/contrib/detectors/gcp"
	"go.opentelemetry.io/otel/sdk/resource"
)

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/computeMetadata/v1/project/project-id", func(w http.ResponseWriter, r *http.Request) {
		if r.Header.Get("Metadata-Flavor") != "Google" {
			http.Error(w, "forbidden", http.StatusForbidden)
			return
		}
		_, _ = w.Write([]byte("demo-acct"))
	})
	mux.HandleFunc("/computeMetadata/v1/instance/machine-type", func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write([]byte("e2-standard-2"))
	})
	mux.HandleFunc("/computeMetadata/v1/instance/zone", func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write([]byte("projects/100/zones/us-central1-a"))
	})
	mux.HandleFunc("/computeMetadata/v1/instance/region", func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write([]byte("projects/100/regions/us-central1"))
	})
	mux.HandleFunc("/computeMetadata/v1/instance/id", func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write([]byte("1001"))
	})
	mux.HandleFunc("/computeMetadata/v1/instance/name", func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write([]byte("node-1"))
	})
	mux.HandleFunc("/computeMetadata/v1/instance/hostname", func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write([]byte("node-1.example.com"))
	})

	srv := httptest.NewServer(mux)
	defer srv.Close()

	if err := os.Setenv("GCE_METADATA_HOST", srv.Listener.Addr().String()); err != nil {
		fmt.Fprintf(os.Stderr, "failed to set GCE_METADATA_HOST: %v\n", err)
		os.Exit(1)
	}
	for _, k := range []string{"KUBERNETES_SERVICE_HOST", "K_CONFIGURATION", "K_SERVICE", "K_REVISION", "FUNCTION_TARGET", "CLOUD_RUN_JOB", "GAE_SERVICE", "GAE_ENV", "BMS_PROJECT_ID"} {
		_ = os.Unsetenv(k)
	}

	ctx := context.Background()

	// 1. gcp.NewDetector returns a non-nil resource.Detector implementation
	detector := gcp.NewDetector()
	var iface resource.Detector = detector
	if iface == nil {
		fmt.Fprintf(os.Stderr, "gcp.NewDetector() returned nil\n")
		os.Exit(1)
	}

	// 2. Detect on GCE populates cloud, host, and gcp.gce.instance attributes from metadata
	res, attrs, err := sample.DetectGCPResource(ctx)
	if err != nil {
		fmt.Fprintf(os.Stderr, "DetectGCPResource on GCE returned error: %v\n", err)
		os.Exit(1)
	}
	if res == nil {
		fmt.Fprintf(os.Stderr, "DetectGCPResource returned nil resource\n")
		os.Exit(1)
	}

	expectedGCE := map[string]string{
		"cloud.provider":            "gcp",
		"cloud.platform":            "gcp_compute_engine",
		"cloud.account.id":          "demo-acct",
		"cloud.availability_zone":   "us-central1-a",
		"cloud.region":              "us-central1",
		"host.type":                 "e2-standard-2",
		"host.id":                   "1001",
		"host.name":                 "node-1",
		"gcp.gce.instance.name":     "node-1",
		"gcp.gce.instance.hostname": "node-1.example.com",
	}
	for k, want := range expectedGCE {
		if got := attrs[k]; got != want {
			fmt.Fprintf(os.Stderr, "GCE attribute %q = %q, want %q\n", k, got, want)
			os.Exit(1)
		}
	}

	// 3. Detect on Cloud Run populates cloud_run platform and faas.* resource attributes
	_ = os.Setenv("K_CONFIGURATION", "cfg-1")
	_ = os.Setenv("K_SERVICE", "svc-1")
	_ = os.Setenv("K_REVISION", "rev-1")
	defer func() {
		_ = os.Unsetenv("K_CONFIGURATION")
		_ = os.Unsetenv("K_SERVICE")
		_ = os.Unsetenv("K_REVISION")
	}()

	_, crAttrs, err := sample.DetectGCPResource(ctx)
	if err != nil {
		fmt.Fprintf(os.Stderr, "DetectGCPResource on Cloud Run returned error: %v\n", err)
		os.Exit(1)
	}
	expectedCR := map[string]string{
		"cloud.provider":   "gcp",
		"cloud.platform":   "gcp_cloud_run",
		"cloud.account.id": "demo-acct",
		"cloud.region":     "us-central1",
		"faas.name":        "svc-1",
		"faas.version":     "rev-1",
		"faas.instance":    "1001",
	}
	for k, want := range expectedCR {
		if got := crAttrs[k]; got != want {
			fmt.Fprintf(os.Stderr, "Cloud Run attribute %q = %q, want %q\n", k, got, want)
			os.Exit(1)
		}
	}

	// 4. resource.WithDetectors(gcp.NewDetector()) integrates with OpenTelemetry SDK resource.New
	sdkRes, err := resource.New(ctx, resource.WithDetectors(sample.NewGCPResourceDetector()))
	if err != nil || sdkRes == nil {
		fmt.Fprintf(os.Stderr, "resource.New with gcp.NewDetector failed: res=%v err=%v\n", sdkRes, err)
		os.Exit(1)
	}

	fmt.Println("All gcp.NewDetector contract assertions passed.")
}