IPv6 support

[clementd64]

When K2D_ADVERTISE_ADDR is set to an IPv6, the server crash

unable to get advertise IP address: invalid IP address: 2001:db8::1

When k2d_net is created with IPv6 enabled, the assigned IPv6 is not show in the Service.

Also he Service's ipFamilies field is ignored, leading to confusing case where IPv6-only is "requested" and an IPv4 is showed.

$ docker inspect k2d_net
[
    {
        "Name": "k2d_net",
        // ...
        "EnableIPv6": true,
        "IPAM": {
            "Driver": "default",
            "Options": {},
            "Config": [
                {
                    "Subnet": "172.17.2.0/24",
                    "Gateway": "172.17.2.1"
                },
                {
                    "Subnet": "fd7d:a40b:9c6::/64",
                    "Gateway": "fd7d:a40b:9c6::1/64"
                }
            ]
        },
        // ...
    }
]

$ kubectl get svc my-nginx-svc -o yaml
apiVersion: v1
kind: Service
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: ...
  creationTimestamp: "2023-08-10T13:12:31Z"
  labels:
    app: nginx
  name: my-nginx-svc
  namespace: default
spec:
  clusterIPs:
  - 172.17.2.2
  ipFamilies:
  - IPv6
  ipFamilyPolicy: PreferDualStack
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: nginx
  type: ClusterIP
status:
  loadBalancer: {}

Simply getting the IPAddress and GlobalIPv6Address if not empty and based of the content of ipFamilies can do the trick. https://github.com/portainer/k2d/blob/4e79c4c944f0b35ab552153a22032cb116391c6b/internal/adapter/converter/service.go#L72

[ncresswell]

Thanks for the report. We didnt build IPv6 into the Alpha version, but can add this into the Beta... will add to backlog for the Beta.

[olljanat]

Btw. Docker IPv6 supports is known to be very buggy https://github.com/moby/moby/issues?q=is%3Aissue+is%3Aopen+ipv6 so I would recommend to wait that libnetwork refactoring work is ready https://github.com/moby/moby/pulls?q=is%3Apr+is%3Aopen+libnetwork because really using IPv6 option but of course support for it can be already implemented in here.