return IP address using kubeconfig --internal

[aojea]

Before 0.8.0 kind get kubeconfig --internal returned the container
IP address of the node with the API server.

Since we added docker custom bridges, the behavior changed
returning the hostname.

We recover the previous behavior returning an IP address, however,
it will return always an IPv4 address.

Fixes: #1558

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[aojea]

/assign @BenTheElder

I'm not super happy but I couldn't find a "clean" way of getting the cluster IP family without adding a new method to the provider or a new variable indicating it.

Totally open to suggestions

[k8s-ci-robot]

@aojea: The following tests failed, say /retest to rerun all failed tests:

Test name	Commit	Details	Rerun command
pull-kind-conformance-parallel-ipv6	3839cf8	link	/test pull-kind-conformance-parallel-ipv6
pull-kind-e2e-kubernetes-1-18	3839cf8	link	/test pull-kind-e2e-kubernetes-1-18

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[BenTheElder]

I don't think most internal clients should use IP still.

…

On Wed, May 13, 2020, 04:15 Kubernetes Prow Robot ***@***.***> wrote: Assigned #1583 <#1583> to @BenTheElder <https://github.com/BenTheElder>. — You are receiving this because you were assigned. Reply to this email directly, view it on GitHub <#1583 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAHADKZGP5IDRBCMYZCBVCLRRJ6MBANCNFSM4M7U4B6A> .

[aojea]

I don't think most internal clients should use IP still.
…

IIRC that the original purpose of the flag was for obtaining the docker IP, it may be used for other containers that do not belong to the cluster.
Internal clients on the nodes can access directly the /etc/kubernetes/kubeadm.config

[aojea]

adding a new parameter is too gross?
--internal (ipv4|ipv6|dns) (default ipv4)

[BenTheElder]

IIRC that the original purpose of the flag was for obtaining the docker IP, it may be used for other containers that do not belong to the cluster.

no, the purpose of the flag is to obtain a kubeconfig for use inside the cluster network as opposed to the one we export for the host.

wanting it to be an IP instead of whatever the internal default management is is ... different.
it should probably be it's own flag, technically it could apply to the host but probably have a different default (host default to IP to avoid issues where we don't control /etc/hosts, internal default to dns...)

[k8s-ci-robot]

@aojea: PR needs rebase.

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[BenTheElder]

btw when I tag an issue kind/design that's because we need to design something like this new flag, I wouldn't have tagged a trivial fix this way 🙃
I'm not sure what the clearest flags would be.

[aojea]

heh my fault, honestly, didn't see the tags and make my mind around it thinking that they only wanted the IPs, let's close and discuss then
/close

[k8s-ci-robot]

@aojea: Closed this PR.

In response to this:

heh my fault, honestly, didn't see the tags and make my mind around it thinking that they only wanted the IPs, let's close and discuss then
/close

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