Allow IPv6-only subnets

cmd/kops/integration_test.go

@@ -299,7 +299,7 @@ func TestMinimalIPv6(t *testing.T) {
 // TestMinimalIPv6 runs the test on a minimum IPv6 configuration
 func TestMinimalIPv6Private(t *testing.T) {
 	newIntegrationTest("minimal-ipv6.example.com", "minimal-ipv6-private").
-		withAddons(awsCCMAddon, awsEBSCSIAddon, dnsControllerAddon).
+		withAddons(awsCCMAddon, awsEBSCSIAddon, dnsControllerAddon, leaderElectionAddon).
 		runTestTerraformAWS(t)
 }
 

pkg/apis/kops/validation/legacy.go

@@ -338,7 +338,11 @@ func ValidateCluster(c *kops.Cluster, strict bool) field.ErrorList {
 			fieldSubnet := fieldSpec.Child("subnets").Index(i)
 			if s.CIDR == "" {
 				if requiresSubnetCIDR && strict {
-					allErrs = append(allErrs, field.Required(fieldSubnet.Child("cidr"), "subnet did not have a cidr set"))
+					if !strings.Contains(c.Spec.NonMasqueradeCIDR, ":") || s.IPv6CIDR == "" {
+						allErrs = append(allErrs, field.Required(fieldSubnet.Child("cidr"), "subnet did not have a cidr set"))
+					} else if c.IsKubernetesLT("1.23") {
+						allErrs = append(allErrs, field.Required(fieldSubnet.Child("cidr"), "IPv6-only subnets require Kubernetes 1.23+"))
+					}
 				}
 			} else {
 				_, subnetCIDR, err := net.ParseCIDR(s.CIDR)

pkg/apis/kops/validation/validation.go

@@ -104,7 +104,7 @@ func validateClusterSpec(spec *kops.ClusterSpec, c *kops.Cluster, fieldPath *fie
 	}
 
 	if spec.Topology != nil {
-		allErrs = append(allErrs, validateTopology(spec.Topology, fieldPath.Child("topology"))...)
+		allErrs = append(allErrs, validateTopology(c, spec.Topology, fieldPath.Child("topology"))...)
 	}
 
 	// UpdatePolicy
@@ -360,7 +360,7 @@ func validateIPv6CIDR(cidr string, fieldPath *field.Path) field.ErrorList {
 	return allErrs
 }
 
-func validateTopology(topology *kops.TopologySpec, fieldPath *field.Path) field.ErrorList {
+func validateTopology(c *kops.Cluster, topology *kops.TopologySpec, fieldPath *field.Path) field.ErrorList {
 	allErrs := field.ErrorList{}
 
 	if topology.Masters == "" {
@@ -373,6 +373,10 @@ func validateTopology(topology *kops.TopologySpec, fieldPath *field.Path) field.
 		allErrs = append(allErrs, field.Required(fieldPath.Child("nodes"), ""))
 	} else {
 		allErrs = append(allErrs, IsValidValue(fieldPath.Child("nodes"), &topology.Nodes, kops.SupportedTopologies)...)
+
+		if topology.Nodes == "private" && c.Spec.IsIPv6Only() && c.IsKubernetesLT("1.23") {
+			allErrs = append(allErrs, field.Forbidden(fieldPath.Child("nodes"), "private topology in IPv6 clusters requires Kubernetes 1.23+"))
+		}
 	}
 
 	if topology.Bastion != nil {

pkg/model/awsmodel/network.go

@@ -254,7 +254,6 @@ func (b *NetworkModelBuilder) Build(c *fi.ModelBuilderContext) error {
 			Lifecycle:        b.Lifecycle,
 			VPC:              b.LinkToVPC(),
 			AvailabilityZone: fi.String(subnetSpec.Zone),
-			CIDR:             fi.String(subnetSpec.CIDR),
 			Shared:           fi.Bool(sharedSubnet),
 			Tags:             tags,
 		}
@@ -263,6 +262,10 @@ func (b *NetworkModelBuilder) Build(c *fi.ModelBuilderContext) error {
 			subnet.ResourceBasedNaming = fi.Bool(true)
 		}
 
+		if subnetSpec.CIDR != "" {
+			subnet.CIDR = fi.String(subnetSpec.CIDR)
+		}
+
 		if subnetSpec.IPv6CIDR != "" {
 			if !sharedVPC {
 				subnet.AmazonIPv6CIDR = b.LinkToAmazonVPCIPv6CIDR()

tests/integration/update_cluster/minimal-ipv6-private/in-v1alpha2.yaml

@@ -33,7 +33,7 @@ spec:
   iam: {}
   kubelet:
     anonymousAuth: false
-  kubernetesVersion: v1.21.0
+  kubernetesVersion: v1.23.0
   masterInternalName: api.internal.minimal-ipv6.example.com
   masterPublicName: api.minimal-ipv6.example.com
   networkCIDR: 172.20.0.0/16

upup/pkg/fi/cloudup/awstasks/subnet.go

@@ -106,7 +106,7 @@ func (e *Subnet) Find(c *fi.Context) (*Subnet, error) {
 
 	actual.ResourceBasedNaming = fi.Bool(aws.StringValue(subnet.PrivateDnsNameOptionsOnLaunch.HostnameType) == ec2.HostnameTypeResourceName)
 	if *actual.ResourceBasedNaming {
-		if !aws.BoolValue(subnet.PrivateDnsNameOptionsOnLaunch.EnableResourceNameDnsARecord) {
+		if fi.StringValue(actual.CIDR) != "" && !aws.BoolValue(subnet.PrivateDnsNameOptionsOnLaunch.EnableResourceNameDnsARecord) {
 			actual.ResourceBasedNaming = nil
 		}
 		if fi.StringValue(actual.IPv6CIDR) != "" && !aws.BoolValue(subnet.PrivateDnsNameOptionsOnLaunch.EnableResourceNameDnsAAAARecord) {
@@ -175,9 +175,8 @@ func (s *Subnet) CheckChanges(a, e, changes *Subnet) error {
 			errors = append(errors, field.Required(fieldPath.Child("VPC"), "must specify a VPC"))
 		}
 
-		if e.CIDR == nil {
+		if e.CIDR == nil && e.IPv6CIDR == nil {
-			// TODO: Auto-assign CIDR?
+			errors = append(errors, field.Required(fieldPath.Child("CIDR"), "must specify a CIDR or IPv6CIDR"))
-			errors = append(errors, field.Required(fieldPath.Child("CIDR"), "must specify a CIDR"))
 		}
 	}
 
@@ -256,7 +255,7 @@ func (_ *Subnet) RenderAWS(t *awsup.AWSAPITarget, a, e, changes *Subnet) error {
 	}
 
 	if a == nil {
-		klog.V(2).Infof("Creating Subnet with CIDR: %q", *e.CIDR)
+		klog.V(2).Infof("Creating Subnet with CIDR: %q IPv6CIDR: %q", fi.StringValue(e.CIDR), fi.StringValue(e.IPv6CIDR))
 
 		request := &ec2.CreateSubnetInput{
 			CidrBlock:         e.CIDR,
@@ -266,6 +265,10 @@ func (_ *Subnet) RenderAWS(t *awsup.AWSAPITarget, a, e, changes *Subnet) error {
 			TagSpecifications: awsup.EC2TagSpecification(ec2.ResourceTypeSubnet, e.Tags),
 		}
 
+		if e.CIDR == nil {
+			request.Ipv6Native = aws.Bool(true)
+		}
+
 		response, err := t.Cloud.EC2().CreateSubnet(request)
 		if err != nil {
 			return fmt.Errorf("error creating subnet: %v", err)
@@ -300,13 +303,24 @@ func (_ *Subnet) RenderAWS(t *awsup.AWSAPITarget, a, e, changes *Subnet) error {
 			return fmt.Errorf("error modifying hostname type: %w", err)
 		}
 
-		request = &ec2.ModifySubnetAttributeInput{
+		if fi.StringValue(e.CIDR) == "" {
-			SubnetId:                             e.ID,
+			request = &ec2.ModifySubnetAttributeInput{
-			EnableResourceNameDnsARecordOnLaunch: &ec2.AttributeBooleanValue{Value: changes.ResourceBasedNaming},
+				SubnetId:    e.ID,
-		}
+				EnableDns64: &ec2.AttributeBooleanValue{Value: aws.Bool(true)},
-		_, err = t.Cloud.EC2().ModifySubnetAttribute(request)
+			}
-		if err != nil {
+			_, err = t.Cloud.EC2().ModifySubnetAttribute(request)
-			return fmt.Errorf("error modifying A records: %w", err)
+			if err != nil {
+				return fmt.Errorf("error enabling DNS64: %w", err)
+			}
+		} else {
+			request = &ec2.ModifySubnetAttributeInput{
+				SubnetId:                             e.ID,
+				EnableResourceNameDnsARecordOnLaunch: &ec2.AttributeBooleanValue{Value: changes.ResourceBasedNaming},
+			}
+			_, err = t.Cloud.EC2().ModifySubnetAttribute(request)
+			if err != nil {
+				return fmt.Errorf("error modifying A records: %w", err)
+			}
 		}
 
 		if fi.StringValue(e.IPv6CIDR) != "" {

upup/pkg/fi/cloudup/subnets.go

@@ -174,6 +174,10 @@ func assignCIDRsToSubnets(c *kops.Cluster, cloud fi.Cloud) error {
 		if subnet.CIDR != "" {
 			continue
 		}
+		// TODO: Replace this with a check against type "dualstack" if has IPv6CIDR
+		if subnet.IPv6CIDR != "" && subnet.Name != subnet.Zone {
+			continue
+		}
 
 		if len(bigCIDRs) == 0 {
 			return fmt.Errorf("insufficient (big) CIDRs remaining for automatic CIDR allocation to subnet %q", subnet.Name)