Allow specifying network stack type

kubetest2-gke/deployer/deployer.go

@@ -49,6 +49,11 @@ const (
 	gceStockoutErrorPattern = ".*does not have enough resources available to fulfill.*"
 )
 
+const (
+	networkStackTypeIPv4     = "IPv4"
+	networkStackTypeIPv4IPv6 = "IPv4_IPv6"
+)
+
 type privateClusterAccessLevel string
 
 const (
@@ -199,7 +204,8 @@ func NewDeployer(opts types.Options) *Deployer {
 			BoskosProjectsRequested:        []int{1},
 		},
 		NetworkOptions: &options.NetworkOptions{
-			Network: "default",
+			Network:   "default",
+			StackType: networkStackTypeIPv4,
 		},
 		ClusterOptions: &options.ClusterOptions{
 			Environment: "prod",

kubetest2-gke/deployer/network.go

@@ -152,8 +152,9 @@ func (d *Deployer) CreateNetwork() error {
 	// For multiple projects profile, the subnet-mode must be custom and should only be created in the host project.
 	//   (Here we consider the first project to be the host project and the rest be service projects)
 	//   Reference: https://cloud.google.com/kubernetes-engine/docs/how-to/cluster-shared-vpc#creating_a_network_and_two_subnets
+	// Additionally, for network stack type different from IPv4, the subnet mode must be custom too.
 	subnetMode := "auto"
-	if len(d.Projects) > 1 {
+	if len(d.Projects) > 1 || d.StackType != networkStackTypeIPv4 {
 		subnetMode = "custom"
 	}
 	if runWithNoOutput(exec.Command("gcloud", "compute", "networks", "describe", d.Network,
@@ -162,9 +163,15 @@ func (d *Deployer) CreateNetwork() error {
 		// Assume error implies non-existent.
 		// TODO(chizhg): find a more reliable way to check if the network exists or not.
 		klog.V(1).Infof("Couldn't describe network %q, assuming it doesn't exist and creating it", d.Network)
-		if err := runWithOutput(exec.Command("gcloud", "compute", "networks", "create", d.Network,
-			"--project="+d.Projects[0],
-			"--subnet-mode="+subnetMode)); err != nil {
+		args := []string{"compute", "networks", "create", d.Network, "--project=" + d.Projects[0], "--subnet-mode=" + subnetMode}
+
+		if d.StackType == networkStackTypeIPv4IPv6 {
+			// Currently dual stack networks only use an internal IP address range. If needed, this switch can be offered
+			// through a kubetest flag.
+			args = append(args, "--enable-ula-internal-ipv6")
+		}
+
+		if err := runWithOutput(exec.Command("gcloud", args...)); err != nil {
 			return err
 		}
 	}

kubetest2-gke/deployer/options/network.go

@@ -22,4 +22,5 @@ type NetworkOptions struct {
 	PrivateClusterAccessLevel    string   `flag:"~private-cluster-access-level" desc:"Private cluster access level, if not empty, must be one of 'no', 'limited' or 'unrestricted'. See the details in https://cloud.google.com/kubernetes-engine/docs/how-to/private-clusters."`
 	PrivateClusterMasterIPRanges []string `flag:"~private-cluster-master-ip-range" desc:"Private cluster master IP ranges. It should be IPv4 CIDR(s), and its length must be the same as the number of clusters if private cluster is requested."`
 	SubnetworkRanges             []string `flag:"~subnetwork-ranges" desc:"Subnetwork ranges as required for shared VPC setup as described in https://cloud.google.com/kubernetes-engine/docs/how-to/cluster-shared-vpc#creating_a_network_and_two_subnets. For multi-project profile, it is required and should be in the format of 10.0.4.0/22 10.0.32.0/20 10.4.0.0/14,172.16.4.0/22 172.16.16.0/20 172.16.4.0/22, where the subnetworks configuration for different project are separated by comma, and the ranges of each subnetwork configuration is separated by space."`
+	StackType                    string   `flag:"~network-stack-type" desc:"Stack type of the network, one of 'IPv4' or 'IPv4_IPv6'. Defaults to 'IPv4' if not provided."`
 }