handle non-gce platforms

detectors/gcp/detector.go

@@ -32,7 +32,7 @@ func NewDetector() *Detector {
 type Platform int64
 
 const (
-	Undefined Platform = iota
+	UnknownPlatform Platform = iota
 	GKE
 	GCE
 	CloudRun
@@ -51,9 +51,10 @@ func (d *Detector) CloudPlatform() Platform {
 		return CloudFunctions
 	case d.onAppEngine():
 		return AppEngine
-	default:
+	case d.onGCE():
 		return GCE
 	}
+	return UnknownPlatform
 }
 
 // ProjectID returns the ID of the project in which this program is running

detectors/gcp/gce.go

@@ -23,6 +23,11 @@ import (
 // https://cloud.google.com/compute/docs/metadata/default-metadata-values#vm_instance_metadata
 const machineTypeMetadataAttr = "instance/machine-type"
 
+func (d *Detector) onGCE() bool {
+	_, err := d.metadata.Get(machineTypeMetadataAttr)
+	return err == nil
+}
+
 // GCEHostType returns the machine type of the instance on which this program is running
 func (d *Detector) GCEHostType() (string, error) {
 	return d.metadata.Get(machineTypeMetadataAttr)

e2e-test-server/endtoendserver/server.go

@@ -213,7 +213,7 @@ func (d *testDetector) Detect(ctx context.Context) (*resource.Resource, error) {
 			semconv.FaaSVersionKey: detector.AppEngineServiceVersion,
 			semconv.FaaSIDKey:      detector.AppEngineServiceInstance,
 		})
-	default:
+	case gcp.GCE:
 		attributes = append(attributes, semconv.CloudPlatformGCPComputeEngine)
 		zone, region, err := detector.GCEAvailabilityZoneAndRegion()
 		if err != nil {
@@ -226,6 +226,8 @@ func (d *testDetector) Detect(ctx context.Context) (*resource.Resource, error) {
 			semconv.HostIDKey:   detector.GCEHostID,
 			semconv.HostNameKey: detector.GCEHostName,
 		})
+	default:
+		return resource.NewWithAttributes(semconv.SchemaURL, attributes...), nil
 	}
 }