Add support for IPv6 pod range.

[marqc]

IPv6 addresses are supported when using a simplified spec template for ipam plugin:

{
  "name": "gke-pod-network",
  "cniVersion": "0.3.1",
  "plugins": [
    {
      "type": "@cniType",
      "mtu": @mtu,
      "ipam": {
          "type": "host-local",
          "ranges": [
            @subnets
          ],
          "routes": [
            @routes
          ]
      }
    },
    {
      "type": "portmap",
      "capabilities": {
        "portMappings": true
      }
    }@cniBandwidthPlugin@cniCiliumPlugin@cniIstioPlugin
  ]
}

Compatibility of new template spec with other use cases is covered in install-cni.sh tests.

[jingyuanliang]

Could you add a testcase where netd is used to generate calico conf file?

[marqc]

@jingyuanliang Thanks for suggestions. All applied

[sdmodi]

We cannot make this change live till CCM is fixed to not populate the IPv6 address in the podCIDR for single stack IPv4 clusters on dual stack subnets. Today, we do this even when the cluster's stack type is IPv4.

[jingyuanliang]

Can we just fix CCM to match the expectation?

[sdmodi]

I believe we are already working on this. CCM needs this bug fix regardless.

[jingyuanliang]

Okay your point is just to hold netd versions with this codepath and don't release it earlier than CCM with the change, right?

[sdmodi]

Yes. Exactly.

[jingyuanliang]

@sdmodi do you have the ETA or timeline of the fix?

[aojea]

it is ready to merge kubernetes/cloud-provider-gcp#652 , I'm waiting for a last pass from Sudeep

[jingyuanliang]

/lgtm
/approve

[google-oss-prow]

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