Lazy initialization of network urls for GCE provider

Author: wojtek-t

staging/src/k8s.io/legacy-cloud-providers/gce/gce.go

@@ -99,6 +99,13 @@ type Cloud struct {
 	// for the cloudprovider to start watching the configmap.
 	ClusterID ClusterID
 
+	// initializer is used for lazy initialization of subnetworkURL
+	// and isLegacyNetwork fields if they are not passed via the config.
+	// The reason is to avoid GCE API calls to initialize them if they
+	// will never be used. This is especially important when
+	// it is run from Kubelets, as there can be thousands  of them.
+	subnetworkURLAndIsLegacyNetworkInitializer sync.Once
+
 	service          *compute.Service
 	serviceBeta      *computebeta.Service
 	serviceAlpha     *computealpha.Service
@@ -115,10 +122,14 @@ type Cloud struct {
 	// managedZones will be set to the 1 zone if running a single zone cluster
 	// it will be set to ALL zones in region for any multi-zone cluster
 	// Use GetAllCurrentZones to get only zones that contain nodes
-	managedZones             []string
-	networkURL               string
-	isLegacyNetwork          bool
-	subnetworkURL            string
+	managedZones []string
+	networkURL   string
+	// unsafeIsLegacyNetwork should be used only via IsLegacyNetwork() accessor,
+	// to ensure it was properly initialized.
+	unsafeIsLegacyNetwork bool
+	// unsafeSubnetworkURL should be used only via SubnetworkURL() accessor,
+	// to ensure it was properly initialized.
+	unsafeSubnetworkURL      string
 	secondaryRangeName       string
 	networkProjectID         string
 	onXPN                    bool
@@ -465,32 +476,12 @@ func CreateGCECloud(config *CloudConfig) (*Cloud, error) {
 		subnetURL = config.SubnetworkURL
 	} else if config.SubnetworkName != "" {
 		subnetURL = gceSubnetworkURL(config.APIEndpoint, netProjID, config.Region, config.SubnetworkName)
-	} else {
-		// Determine the type of network and attempt to discover the correct subnet for AUTO mode.
-		// Gracefully fail because kubelet calls CreateGCECloud without any config, and minions
-		// lack the proper credentials for API calls.
-		if networkName := lastComponent(networkURL); networkName != "" {
-			var n *compute.Network
-			if n, err = getNetwork(service, netProjID, networkName); err != nil {
-				klog.Warningf("Could not retrieve network %q; err: %v", networkName, err)
-			} else {
-				switch typeOfNetwork(n) {
-				case netTypeLegacy:
-					klog.Infof("Network %q is type legacy - no subnetwork", networkName)
-					isLegacyNetwork = true
-				case netTypeCustom:
-					klog.Warningf("Network %q is type custom - cannot auto select a subnetwork", networkName)
-				case netTypeAuto:
-					subnetURL, err = determineSubnetURL(service, netProjID, networkName, config.Region)
-					if err != nil {
-						klog.Warningf("Could not determine subnetwork for network %q and region %v; err: %v", networkName, config.Region, err)
-					} else {
-						klog.Infof("Auto selecting subnetwork %q", subnetURL)
-					}
-				}
-			}
-		}
 	}
+	// If neither SubnetworkURL nor SubnetworkName are provided, defer to
+	// lazy initialization. Determining subnetURL and isLegacyNetwork requires
+	// GCE API call. Given that it's not used in many cases and the fact that
+	// the provider is initialized also for Kubelets (and there can be thousands
+	// of them) we defer to lazy initialization here.
 
 	if len(config.ManagedZones) == 0 {
 		config.ManagedZones, err = getZonesForRegion(service, config.ProjectID, config.Region)
@@ -518,8 +509,8 @@ func CreateGCECloud(config *CloudConfig) (*Cloud, error) {
 		localZone:                config.Zone,
 		managedZones:             config.ManagedZones,
 		networkURL:               networkURL,
-		isLegacyNetwork:          isLegacyNetwork,
-		subnetworkURL:            subnetURL,
+		unsafeIsLegacyNetwork:    isLegacyNetwork,
+		unsafeSubnetworkURL:      subnetURL,
 		secondaryRangeName:       config.SecondaryRangeName,
 		nodeTags:                 config.NodeTags,
 		nodeInstancePrefix:       config.NodeInstancePrefix,
@@ -542,6 +533,45 @@ func CreateGCECloud(config *CloudConfig) (*Cloud, error) {
 	return gce, nil
 }
 
+// initializeNetworkConfig() is supposed to be called under sync.Once()
+// for accessors to subnetworkURL and isLegacyNetwork fields.
+func (g *Cloud) initializeSubnetworkURLAndIsLegacyNetwork() {
+	if g.unsafeSubnetworkURL != "" {
+		// This has already been initialized via the config.
+		return
+	}
+
+	var subnetURL string
+	var isLegacyNetwork bool
+
+	// Determine the type of network and attempt to discover the correct subnet for AUTO mode.
+	// Gracefully fail because kubelet calls CreateGCECloud without any config, and minions
+	// lack the proper credentials for API calls.
+	if networkName := lastComponent(g.NetworkURL()); networkName != "" {
+		if n, err := getNetwork(g.service, g.NetworkProjectID(), networkName); err != nil {
+			klog.Warningf("Could not retrieve network %q; err: %v", networkName, err)
+		} else {
+			switch typeOfNetwork(n) {
+			case netTypeLegacy:
+				klog.Infof("Network %q is type legacy - no subnetwork", networkName)
+				isLegacyNetwork = true
+			case netTypeCustom:
+				klog.Warningf("Network %q is type custom - cannot auto select a subnetwork", networkName)
+			case netTypeAuto:
+				subnetURL, err = determineSubnetURL(g.service, g.NetworkProjectID(), networkName, g.Region())
+				if err != nil {
+					klog.Warningf("Could not determine subnetwork for network %q and region %v; err: %v", networkName, g.Region(), err)
+				} else {
+					klog.Infof("Auto selecting subnetwork %q", subnetURL)
+				}
+			}
+		}
+	}
+
+	g.unsafeSubnetworkURL = subnetURL
+	g.unsafeIsLegacyNetwork = isLegacyNetwork
+}
+
 // SetRateLimiter adds a custom cloud.RateLimiter implementation.
 // WARNING: Calling this could have unexpected behavior if you have in-flight
 // requests. It is best to use this immediately after creating a Cloud.
@@ -672,12 +702,14 @@ func (g *Cloud) NetworkURL() string {
 
 // SubnetworkURL returns the subnetwork url
 func (g *Cloud) SubnetworkURL() string {
-	return g.subnetworkURL
+	g.subnetworkURLAndIsLegacyNetworkInitializer.Do(g.initializeSubnetworkURLAndIsLegacyNetwork)
+	return g.unsafeSubnetworkURL
 }
 
 // IsLegacyNetwork returns true if the cluster is still running a legacy network configuration.
 func (g *Cloud) IsLegacyNetwork() bool {
-	return g.isLegacyNetwork
+	g.subnetworkURLAndIsLegacyNetworkInitializer.Do(g.initializeSubnetworkURLAndIsLegacyNetwork)
+	return g.unsafeIsLegacyNetwork
 }
 
 // SetInformers sets up the zone handlers we need watching for node changes.

staging/src/k8s.io/legacy-cloud-providers/gce/gce_loadbalancer_internal.go

@@ -75,7 +75,7 @@ func (g *Cloud) ensureInternalLoadBalancer(clusterName, clusterID string, svc *v
 	}
 	scheme := cloud.SchemeInternal
 	options := getILBOptions(svc)
-	if g.isLegacyNetwork {
+	if g.IsLegacyNetwork() {
 		g.eventRecorder.Event(svc, v1.EventTypeWarning, "ILBOptionsIgnored", "Internal LoadBalancer options are not supported with Legacy Networks.")
 		options = ILBOptions{}
 	}