Add --ipv6 experimental cli flag

cmd/kops/create_cluster.go

@@ -260,6 +260,10 @@ func NewCmdCreateCluster(f *util.Factory, out io.Writer) *cobra.Command {
 	// TODO: Can we deprecate this flag - it is awkward?
 	cmd.Flags().BoolVar(&associatePublicIP, "associate-public-ip", false, "Specify --associate-public-ip=[true|false] to enable/disable association of public IP for master ASG and nodes. Default is 'true'.")
 
+	if featureflag.AWSIPv6.Enabled() {
+		cmd.Flags().BoolVar(&options.IPv6, "ipv6", false, "Allocate IPv6 CIDRs to sunets for clusters with public topology on AWS")
+	}
+
 	cmd.Flags().StringSliceVar(&options.NodeSecurityGroups, "node-security-groups", options.NodeSecurityGroups, "Add precreated additional security groups to nodes.")
 	cmd.Flags().StringSliceVar(&options.MasterSecurityGroups, "master-security-groups", options.MasterSecurityGroups, "Add precreated additional security groups to masters.")
 

pkg/featureflag/featureflag.go

@@ -99,6 +99,8 @@ var (
 	APIServerNodes = New("APIServerNodes", Bool(false))
 	// UseAddonOperators activates experimental addon operator support
 	UseAddonOperators = New("UseAddonOperators", Bool(false))
+	// AWSIPv6 activates experimental AWS IPv6 support.
+	AWSIPv6 = New("AWSIPv6", Bool(false))
 )
 
 // FeatureFlag defines a feature flag

tests/integration/create_cluster/ipv6/expected-v1alpha2.yaml

@@ -43,6 +43,7 @@ spec:
   - 0.0.0.0/0
   subnets:
   - cidr: 172.20.32.0/19
+    ipv6CIDR: /64#1
     name: us-test-1a
     type: Public
     zone: us-test-1a

tests/integration/create_cluster/ipv6/options.yaml

@@ -4,3 +4,4 @@ Zones:
 CloudProvider: aws
 Networking: calico
 KubernetesVersion: v1.22.0
+IPv6: true

upup/pkg/fi/cloudup/new_cluster.go

@@ -91,6 +91,8 @@ type NewClusterOptions struct {
 	UtilitySubnetIDs []string
 	// Egress defines the method of traffic egress for subnets.
 	Egress string
+	// IPv6 adds IPv6 CIDRs to subnets
+	IPv6 bool
 
 	// OpenstackExternalNet is the name of the external network for the openstack router.
 	OpenstackExternalNet     string
@@ -942,6 +944,19 @@ func setupTopology(opt *NewClusterOptions, cluster *api.Cluster, allZones sets.S
 			cluster.Spec.Subnets[i].Type = api.SubnetTypePublic
 		}
 
+		if opt.IPv6 {
+			if api.CloudProviderID(cluster.Spec.CloudProvider) == api.CloudProviderAWS {
+				klog.Warningf("IPv6 support is EXPERIMENTAL and can be changed or removed at any time in the future!!!")
+				for i := range cluster.Spec.Subnets {
+					// Start IPv6 CIDR numbering from "1" to reserve /64#0 for later use
+					// with NonMasqueradeCIDR, ClusterCIDR and ServiceClusterIPRange
+					cluster.Spec.Subnets[i].IPv6CIDR = fmt.Sprintf("/64#%x", i+1)
+				}
+			} else {
+				klog.Errorf("IPv6 support is available only on AWS")
+			}
+		}
+
 	case api.TopologyPrivate:
 		if cluster.Spec.Networking.Kubenet != nil {
 			return nil, fmt.Errorf("invalid networking option %s. Kubenet does not support private topology", opt.Networking)