Unify and improve GCP resource detection, second attempt (#2310)

* update GCP resource detection

* Apply suggestions from code review

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

* return partial errors

* gotidy

* remove host.name from GKE, since GKE doesn't support it

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

detectors/gcp/README.md

@@ -0,0 +1,57 @@
+# GCP Resource detector
+
+The GCP resource detector supports detecting resources on:
+
+ * Google Compute Engine (GCE)
+ * Google Kubernetes Engine (GKE)
+ * Google App Engine (GAE)
+ * Cloud Run
+ * Cloud Functions
+
+## Usage
+
+```golang
+ctx := context.Background()
+// Detect your resources
+res, err := resource.New(ctx,
+    // Use the GCP resource detector!
+    resource.WithDetectors(gcp.NewDetector()),
+    // Keep the default detectors
+    resource.WithTelemetrySDK(),
+    // Add your own custom attributes to identify your application
+    resource.WithAttributes(
+        semconv.ServiceNameKey.String("my-application"),
+        semconv.ServiceNamespaceKey.String("my-company-frontend-team"),
+    ),
+)
+if err != nil {
+    // Handle err
+}
+// Use the resource in your tracerprovider (or meterprovider)
+tp := trace.NewTracerProvider(
+    // ... other options
+    trace.WithResource(res),
+)
+```
+
+## Setting Kubernetes attributes
+
+Previous iterations of GCP resource detection attempted to detect
+`container.name`, `k8s.pod.name` and `k8s.namespace.name`.  When using this detector,
+you should use this in your Pod Spec to set these using
+`OTEL_RESOURCE_ATTRIBUTES`:
+
+```yaml
+env:
+- name: POD_NAME
+  valueFrom:
+    fieldRef:
+      fieldPath: metadata.name
+- name: NAMESPACE_NAME
+  valueFrom:
+    fieldRef:
+      fieldPath: metadata.namespace
+- name: CONTAINER_NAME
+  value: my-container-name
+- name: OTEL_RESOURCE_ATTRIBUTES
+  value: k8s.pod.name=$(POD_NAME),k8s.namespace.name=$(NAMESPACE_NAME),k8s.container.name=$(CONTAINER_NAME)

detectors/gcp/cloud-function.go

@@ -28,6 +28,7 @@ const (
 )
 
 // NewCloudFunction will return a GCP Cloud Function resource detector.
+// Deprecated: Use gcp.NewDetector() instead, which sets the same resource attributes.
 func NewCloudFunction() resource.Detector {
 	return &cloudFunction{
 		cloudRun: NewCloudRun(),

detectors/gcp/cloud-run.go

@@ -38,6 +38,7 @@ type metadataClient interface {
 }
 
 // CloudRun collects resource information of Cloud Run instance.
+// Deprecated: Use gcp.NewDetector() instead. Note that it sets faas.* resource attributes instead of service.* attributes.
 type CloudRun struct {
 	mc     metadataClient
 	onGCE  func() bool
@@ -49,6 +50,7 @@ type CloudRun struct {
 var _ resource.Detector = (*CloudRun)(nil)
 
 // NewCloudRun creates a CloudRun detector.
+// Deprecated: Use gcp.NewDetector() instead. Note that it sets faas.* resource attributes instead of service.* attributes.
 func NewCloudRun() *CloudRun {
 	return &CloudRun{
 		mc:     metadata.NewClient(nil),

detectors/gcp/detector.go

@@ -0,0 +1,135 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gcp // import "go.opentelemetry.io/contrib/detectors/gcp"
+
+import (
+	"context"
+	"fmt"
+
+	"cloud.google.com/go/compute/metadata"
+	"github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/sdk/resource"
+	semconv "go.opentelemetry.io/otel/semconv/v1.10.0"
+)
+
+// NewDetector returns a resource detector which detects resource attributes on:
+// * Google Compute Engine (GCE).
+// * Google Kubernetes Engine (GKE).
+// * Google App Engine (GAE).
+// * Cloud Run.
+// * Cloud Functions.
+func NewDetector() resource.Detector {
+	return &detector{detector: gcp.NewDetector()}
+}
+
+type detector struct {
+	detector gcpDetector
+}
+
+// Detect detects associated resources when running on GCE, GKE, GAE,
+// Cloud Run, and Cloud functions.
+func (d *detector) Detect(ctx context.Context) (*resource.Resource, error) {
+	if !metadata.OnGCE() {
+		return nil, nil
+	}
+	b := &resourceBuilder{}
+	b.attrs = append(b.attrs, semconv.CloudProviderGCP)
+	b.add(semconv.CloudAccountIDKey, d.detector.ProjectID)
+
+	switch d.detector.CloudPlatform() {
+	case gcp.GKE:
+		b.attrs = append(b.attrs, semconv.CloudPlatformGCPKubernetesEngine)
+		b.addZoneOrRegion(d.detector.GKEAvailabilityZoneOrRegion)
+		b.add(semconv.K8SClusterNameKey, d.detector.GKEClusterName)
+		b.add(semconv.HostIDKey, d.detector.GKEHostID)
+	case gcp.CloudRun:
+		b.attrs = append(b.attrs, semconv.CloudPlatformGCPCloudRun)
+		b.add(semconv.FaaSNameKey, d.detector.FaaSName)
+		b.add(semconv.FaaSVersionKey, d.detector.FaaSVersion)
+		b.add(semconv.FaaSIDKey, d.detector.FaaSID)
+		b.add(semconv.CloudRegionKey, d.detector.FaaSCloudRegion)
+	case gcp.CloudFunctions:
+		b.attrs = append(b.attrs, semconv.CloudPlatformGCPCloudFunctions)
+		b.add(semconv.FaaSNameKey, d.detector.FaaSName)
+		b.add(semconv.FaaSVersionKey, d.detector.FaaSVersion)
+		b.add(semconv.FaaSIDKey, d.detector.FaaSID)
+		b.add(semconv.CloudRegionKey, d.detector.FaaSCloudRegion)
+	case gcp.AppEngine:
+		b.attrs = append(b.attrs, semconv.CloudPlatformGCPAppEngine)
+		b.addZoneAndRegion(d.detector.AppEngineAvailabilityZoneAndRegion)
+		b.add(semconv.FaaSNameKey, d.detector.AppEngineServiceName)
+		b.add(semconv.FaaSVersionKey, d.detector.AppEngineServiceVersion)
+		b.add(semconv.FaaSIDKey, d.detector.AppEngineServiceInstance)
+	case gcp.GCE:
+		b.attrs = append(b.attrs, semconv.CloudPlatformGCPComputeEngine)
+		b.addZoneAndRegion(d.detector.GCEAvailabilityZoneAndRegion)
+		b.add(semconv.HostTypeKey, d.detector.GCEHostType)
+		b.add(semconv.HostIDKey, d.detector.GCEHostID)
+		b.add(semconv.HostNameKey, d.detector.GCEHostName)
+	default:
+		// We don't support this platform yet, so just return with what we have
+	}
+	return b.build()
+}
+
+// resourceBuilder simplifies constructing resources using GCP detection
+// library functions.
+type resourceBuilder struct {
+	errs  []error
+	attrs []attribute.KeyValue
+}
+
+func (r *resourceBuilder) add(key attribute.Key, detect func() (string, error)) {
+	if v, err := detect(); err == nil {
+		r.attrs = append(r.attrs, key.String(v))
+	} else {
+		r.errs = append(r.errs, err)
+	}
+}
+
+// zoneAndRegion functions are expected to return zone, region, err.
+func (r *resourceBuilder) addZoneAndRegion(detect func() (string, string, error)) {
+	if zone, region, err := detect(); err == nil {
+		r.attrs = append(r.attrs, semconv.CloudAvailabilityZoneKey.String(zone))
+		r.attrs = append(r.attrs, semconv.CloudRegionKey.String(region))
+	} else {
+		r.errs = append(r.errs, err)
+	}
+}
+
+func (r *resourceBuilder) addZoneOrRegion(detect func() (string, gcp.LocationType, error)) {
+	if v, locType, err := detect(); err == nil {
+		switch locType {
+		case gcp.Zone:
+			r.attrs = append(r.attrs, semconv.CloudAvailabilityZoneKey.String(v))
+		case gcp.Region:
+			r.attrs = append(r.attrs, semconv.CloudRegionKey.String(v))
+		default:
+			r.errs = append(r.errs, fmt.Errorf("location must be zone or region. Got %v", locType))
+		}
+	} else {
+		r.errs = append(r.errs, err)
+	}
+}
+
+func (r *resourceBuilder) build() (*resource.Resource, error) {
+	var err error
+	if len(r.errs) > 0 {
+		err = fmt.Errorf("%w: %s", resource.ErrPartialResource, r.errs)
+	}
+	return resource.NewWithAttributes(semconv.SchemaURL, r.attrs...), err
+}