Merge pull request kubernetes#46366 from nicksardo/gce-subnetwork-url

Automatic merge from submit-queue (batch tested with PRs 45573, 46354, 46376, 46162, 46366)

GCE - Retrieve subnetwork name/url from gce.conf 

**What this PR does / why we need it**:
Features like ILB require specifying the subnetwork if the network is type manual.

**Notes:**
The network URL can be [constructed](https://github.com/nicksardo/kubernetes/blob/68e7e18698d60050924c0f0e8f794a21820f2a1a/pkg/cloudprovider/providers/gce/gce.go#L211-L217) by fetching instance metadata; however, the subnetwork is not provided through this feature. Users must specify the subnetwork name/url through the gce.conf.

Although multiple subnets can exist in the same region for a network, the cloud provider will only use one subnet url for creating LBs. 


**Release note**:
```release-note
NONE
```

cluster/gce/container-linux/configure-helper.sh

@@ -184,6 +184,11 @@ token-body = ${TOKEN_BODY}
 project-id = ${PROJECT_ID}
 network-name = ${NODE_NETWORK}
 EOF
+    if [[ -n "${NODE_SUBNETWORK:-}" ]]; then
+      cat <<EOF >>/etc/gce.conf
+subnetwork-name = ${NODE_SUBNETWORK}
+EOF
+    fi
   fi
   if [[ -n "${NODE_INSTANCE_PREFIX:-}" ]]; then
     use_cloud_config="true"

cluster/gce/gci/configure-helper.sh

@@ -326,6 +326,11 @@ token-body = ${TOKEN_BODY}
 project-id = ${PROJECT_ID}
 network-name = ${NODE_NETWORK}
 EOF
+    if [[ -n "${NODE_SUBNETWORK:-}" ]]; then
+      cat <<EOF >>/etc/gce.conf
+subnetwork-name = ${NODE_SUBNETWORK}
+EOF
+    fi
   fi
   if [[ -n "${NODE_INSTANCE_PREFIX:-}" ]]; then
     use_cloud_config="true"

pkg/cloudprovider/providers/gce/gce.go

@@ -86,6 +86,7 @@ type GCECloud struct {
 	localZone                string   // The zone in which we are running
 	managedZones             []string // List of zones we are spanning (for multi-AZ clusters, primarily when running on master)
 	networkURL               string
+	subnetworkURL            string
 	nodeTags                 []string // List of tags to use on firewall rules for load balancers
 	nodeInstancePrefix       string   // If non-"", an advisory prefix for all nodes in the cluster
 	useMetadataServer        bool
@@ -98,6 +99,7 @@ type Config struct {
 		TokenBody          string   `gcfg:"token-body"`
 		ProjectID          string   `gcfg:"project-id"`
 		NetworkName        string   `gcfg:"network-name"`
+		SubnetworkName     string   `gcfg:"subnetwork-name"`
 		NodeTags           []string `gcfg:"node-tags"`
 		NodeInstancePrefix string   `gcfg:"node-instance-prefix"`
 		Multizone          bool     `gcfg:"multizone"`
@@ -134,6 +136,7 @@ func newGCECloud(config io.Reader) (*GCECloud, error) {
 		return nil, err
 	}
 	networkURL := gceNetworkURL(projectID, networkName)
+	subnetworkURL := ""
 
 	// By default, Kubernetes clusters only run against one zone
 	managedZones := []string{zone}
@@ -158,6 +161,13 @@ func newGCECloud(config io.Reader) (*GCECloud, error) {
 				networkURL = gceNetworkURL(cfg.Global.ProjectID, cfg.Global.NetworkName)
 			}
 		}
+		if cfg.Global.SubnetworkName != "" {
+			if strings.Contains(cfg.Global.SubnetworkName, "/") {
+				subnetworkURL = cfg.Global.SubnetworkName
+			} else {
+				subnetworkURL = gceSubnetworkURL(cfg.Global.ProjectID, region, cfg.Global.SubnetworkName)
+			}
+		}
 		if cfg.Global.TokenURL != "" {
 			tokenSource = NewAltTokenSource(cfg.Global.TokenURL, cfg.Global.TokenBody)
 		}
@@ -168,15 +178,15 @@ func newGCECloud(config io.Reader) (*GCECloud, error) {
 		}
 	}
 
-	return CreateGCECloud(projectID, region, zone, managedZones, networkURL, nodeTags,
-		nodeInstancePrefix, tokenSource, true /* useMetadataServer */)
+	return CreateGCECloud(projectID, region, zone, managedZones, networkURL, subnetworkURL,
+		nodeTags, nodeInstancePrefix, tokenSource, true /* useMetadataServer */)
 }
 
 // Creates a GCECloud object using the specified parameters.
 // If no networkUrl is specified, loads networkName via rest call.
 // If no tokenSource is specified, uses oauth2.DefaultTokenSource.
 // If managedZones is nil / empty all zones in the region will be managed.
-func CreateGCECloud(projectID, region, zone string, managedZones []string, networkURL string, nodeTags []string,
+func CreateGCECloud(projectID, region, zone string, managedZones []string, networkURL, subnetworkURL string, nodeTags []string,
 	nodeInstancePrefix string, tokenSource oauth2.TokenSource, useMetadataServer bool) (*GCECloud, error) {
 
 	client, err := newOauthClient(tokenSource)
@@ -229,6 +239,7 @@ func CreateGCECloud(projectID, region, zone string, managedZones []string, netwo
 		localZone:                zone,
 		managedZones:             managedZones,
 		networkURL:               networkURL,
+		subnetworkURL:            subnetworkURL,
 		nodeTags:                 nodeTags,
 		nodeInstancePrefix:       nodeInstancePrefix,
 		useMetadataServer:        useMetadataServer,
@@ -293,6 +304,10 @@ func gceNetworkURL(project, network string) string {
 	return fmt.Sprintf("https://www.googleapis.com/compute/v1/projects/%s/global/networks/%s", project, network)
 }
 
+func gceSubnetworkURL(project, region, subnetwork string) string {
+	return fmt.Sprintf("https://www.googleapis.com/compute/v1/projects/%s/regions/%s/subnetworks/%s", project, region, subnetwork)
+}
+
 func getNetworkNameViaMetadata() (string, error) {
 	result, err := metadata.Get("instance/network-interfaces/0/network")
 	if err != nil {

test/e2e/e2e.go

@@ -77,7 +77,9 @@ func setupProviderConfig() error {
 		if !framework.TestContext.CloudConfig.MultiZone {
 			managedZones = []string{zone}
 		}
-		cloudConfig.Provider, err = gcecloud.CreateGCECloud(framework.TestContext.CloudConfig.ProjectID, region, zone, managedZones, "" /* networkUrl */, nil /* nodeTags */, "" /* nodeInstancePerfix */, nil /* tokenSource */, false /* useMetadataServer */)
+		cloudConfig.Provider, err = gcecloud.CreateGCECloud(framework.TestContext.CloudConfig.ProjectID,
+			region, zone, managedZones, "" /* networkUrl */, "" /* subnetworkUrl */, nil, /* nodeTags */
+			"" /* nodeInstancePerfix */, nil /* tokenSource */, false /* useMetadataServer */)
 		if err != nil {
 			return fmt.Errorf("Error building GCE/GKE provider: %v", err)
 		}