dns/gcp: Allow configuring custom endpoints

If a custom service endpoint has been configured for DNS, use it when
creating the client for the Google Cloud DNS service.

This feature is behind the "GCPCustomAPIEndpoints" featuregate.

This commit resolves CORS-3907.

https://issues.redhat.com/browse/CORS-3907

* pkg/dns/gcp/provider.go (Config): Add GCPCustomEndpointsEnabled field
to the provider config.
(New): If a custom endpoint is set and the featuregate is enabled,
configure the new client to use the endpoint.
* pkg/operator/controller/dns/controller.go (Config): Add
GCPCustomEndpointsEnabled field.
(createDNSProvider): Pass GCPCustomEndpointsEnabled from the controller
config to the GCP provider config.
* pkg/operator/operator.go (New): Set the controller config field based
on the featuregate.

Author: barbacbd

pkg/dns/gcp/provider.go

@@ -31,13 +31,30 @@ type Provider struct {
 }
 
 type Config struct {
-	Project         string
-	UserAgent       string
-	CredentialsJSON []byte
+	Project                   string
+	UserAgent                 string
+	CredentialsJSON           []byte
+	Endpoints                 []configv1.GCPServiceEndpoint
+	GCPCustomEndpointsEnabled bool
 }
 
 func New(config Config) (*Provider, error) {
-	dnsService, err := gdnsv1.NewService(context.TODO(), option.WithCredentialsJSON(config.CredentialsJSON), option.WithUserAgent(config.UserAgent))
+	options := []option.ClientOption{
+		option.WithCredentialsJSON(config.CredentialsJSON),
+		option.WithUserAgent(config.UserAgent),
+	}
+	if config.GCPCustomEndpointsEnabled {
+		for _, endpoint := range config.Endpoints {
+			if endpoint.Name == configv1.GCPServiceEndpointNameDNS {
+				// There should be at most 1 endpoint override per service. If there
+				// is more than one, only use the first instance.
+				options = append(options, option.WithEndpoint(endpoint.URL))
+				break
+			}
+		}
+	}
+
+	dnsService, err := gdnsv1.NewService(context.TODO(), options...)
 	if err != nil {
 		return nil, err
 	}

pkg/operator/controller/dns/controller.go

@@ -114,6 +114,10 @@ type Config struct {
 	// PrivateHostedZoneAWSEnabled indicates whether the "SharedVPC" feature gate is
 	// enabled.
 	PrivateHostedZoneAWSEnabled bool
+
+	// GCPCustomEndpointsEnabled indicates whether the "GCPCustomAPIEndpoints"
+	// feature gate is enabled.
+	GCPCustomEndpointsEnabled bool
 }
 
 type reconciler struct {
@@ -698,9 +702,11 @@ func (r *reconciler) createDNSProvider(dnsConfig *configv1.DNS, platformStatus *
 		dnsProvider = provider
 	case configv1.GCPPlatformType:
 		provider, err := gcpdns.New(gcpdns.Config{
-			Project:         platformStatus.GCP.ProjectID,
-			CredentialsJSON: creds.Data["service_account.json"],
-			UserAgent:       userAgent,
+			Project:                   platformStatus.GCP.ProjectID,
+			CredentialsJSON:           creds.Data["service_account.json"],
+			UserAgent:                 userAgent,
+			Endpoints:                 platformStatus.GCP.ServiceEndpoints,
+			GCPCustomEndpointsEnabled: r.config.GCPCustomEndpointsEnabled,
 		})
 		if err != nil {
 			return nil, fmt.Errorf("failed to create GCP DNS provider: %v", err)

pkg/operator/operator.go

@@ -137,6 +137,7 @@ func New(config operatorconfig.Config, kubeConfig *rest.Config) (*Operator, erro
 	ingressControllerLBSubnetsAWSEnabled := featureGates.Enabled(features.FeatureGateIngressControllerLBSubnetsAWS)
 	ingressControllerEIPAllocationsAWSEnabled := featureGates.Enabled(features.FeatureGateSetEIPForNLBIngressController)
 	ingressControllerDCMEnabled := featureGates.Enabled(features.FeatureGateIngressControllerDynamicConfigurationManager)
+	gcpCustomEndpointsEnabled := featureGates.Enabled(features.FeatureGateGCPCustomAPIEndpoints)
 
 	// Set up an operator manager for the operator namespace.
 	mgr, err := manager.New(kubeConfig, manager.Options{
@@ -256,6 +257,7 @@ func New(config operatorconfig.Config, kubeConfig *rest.Config) (*Operator, erro
 		OperatorReleaseVersion:       config.OperatorReleaseVersion,
 		AzureWorkloadIdentityEnabled: azureWorkloadIdentityEnabled,
 		PrivateHostedZoneAWSEnabled:  sharedVPCEnabled,
+		GCPCustomEndpointsEnabled:    gcpCustomEndpointsEnabled,
 	}); err != nil {
 		return nil, fmt.Errorf("failed to create dns controller: %v", err)
 	}