Introduce configuration changes for the ipv6 support

[mikhail-sakhnov]

Pass CIDR as separate ENV variables for calico-node
Change default node-cidr-mask-size-ipv6 to be a smaller size value
Enable CALICO_IPV6POOL_NAT_OUTGOING for dualstack setup
Change kube-proxy to ipvs in case of dual-stack setup

closes #394

The changes here enable to create ipv6\ipv4 dualstack setup

Limitations:

• Connections to the outer world work (e.g. curl -6 ipv6.google.com will work from any pod)
• It seems like currently k8s doesn't assign internal ipv6 address automatically on bare-metal, but could be done by workaround with external cloud provider and manual node status update as described in No way to configure ExternalIP addresses for a node with kubelet kubernetes/kubernetes#42125
• each pod gets ipv6 address from the CNI
• cross pod connectivity exists across nodes

Additional links used during this PR:
https://www.projectcalico.org/dual-stack-operation-with-calico-on-kubernetes/
https://docs.projectcalico.org/networking/ipv6
https://kubernetes.io/docs/tasks/network/validate-dual-stack/ (this one mentions how to create dual\single stack services)
https://kubernetes.io/docs/concepts/services-networking/dual-stack/

In case of testing this on AWS the source\destination checks must be disabled on the interface.

k0s.yaml used:

spec:
  network:
    calico:
      mode: "bird"
    dualStack:
      enabled: true
      IPv6podCIDR: "fd00::/108"
      IPv6serviceCIDR: "fd01::/108"

[jnummelin]

Few minor tweaks needed

[unixfox]

Could you allow dual stack mode for custom network provider? Currently, I can't do that due to this error: network dual stack is supported only for calico mode bird.

My config:

network:
    provider: custom
    dualStack:
      enabled: true
      IPv6podCIDR: "fd00::/108"
      IPv6serviceCIDR: "fd01::/108"

EDIT: I got it working by specifying bird calico config even though I'm using a custom network provider. Like this:

network:
    provider: custom
    dualStack:
      enabled: true
      IPv6podCIDR: "fd00::/108"
      IPv6serviceCIDR: "fd01::/108"
    calico:
      mode: "bird"

But that's not the ideal solution.

[unixfox]

Works great! Thank you for your work!

I tested:

• reaching the exposed port of a nodeport from a pod using the nginx image
• pod interconnectivity with pods in other nodes
• connectivity to the internet from a pod

[mikhail-sakhnov]

pported only for calico mode bird

@unixfox should be fixed in latest version

[mikhail-sakhnov]

@unixfox thank you for the help with testing things!