IPv6 egress with IPv4 Cluster/CNI

[jaxxstorm]

trafficstars

I'm trying to determine if this is actually feasible.

I have an AWS VPC configured with subnets that are "dual-stack" - they have IPv4 addresses and IPv6 addresses. There's an IPv6 egress gateway configured, DNS64 and NAT64. If it matters, this is the vpc configuration with Terraform

module "vpc" {
  source = "terraform-aws-modules/vpc/aws"

  name = local.name
  cidr = local.vpc_cidr

  azs                                            = local.azs
  private_subnets                                = local.private_subnet_cidrs
  public_subnets                                 = local.public_subnet_cidrs
  public_subnet_assign_ipv6_address_on_creation  = true
  private_subnet_assign_ipv6_address_on_creation = true
  public_subnet_ipv6_prefixes                    = [0, 1, 2]
  private_subnet_ipv6_prefixes                   = [3, 4, 5]
  enable_nat_gateway                             = true
  enable_ipv6                                    = true

  public_subnet_tags = {
    "kubernetes.io/role/elb" = 1
  }

  private_subnet_tags = {
    "kubernetes.io/role/internal-elb" = 1
  }

  tags = local.tags
}

I can confirm my EKS nodes are getting IPv6 addressess on them.

I've set the CNI variable ENABLE_V6_EGRESS = "true"

I can confirm IPv6 connectivity outbound to the internet, it works great from the nodes

When the node joins, it doesn't get IPv6 forwarding enabled, so I created a daemonset to enable it, and verified that the node has ipv6 forwarding enabled

However, pods themselves have no outbound connectivity on IPv6. There's no route added to the pod, and the ENABLE_V6_EGRESS setting doesn't appear to have helped.

Is it possible to get a cluster where the CNI is obly IPv4 traffic to egress traffic this way, or am I way off base?