Allow creation of "Private Clusters"

[itspngu]

/kind feature

Describe the solution you'd like
Currently, CAPG is hard-wired to create GCE load balancing components with a public IP address for apiserver access. The nodes themselves do not receive public addresses unless explicitly configured as such, the same should apply to the apiserver's endpoint(s). Being able to provision clusters with access limited by private IP address connectivity would be beneficial for obvious reasons.

Anything else you would like to add:
I'm not 100% sure if using private endpoints should be the default - it'd be in line with how address management for nodes currently works, but would also have potential for being a breaking change.

The GKE-specific concept of private clusters is explained here. This feature request is scoped at allowing this to apply for both managed (GKE) and unmanaged (plain Cluster API) clusters.

[k8s-triage-robot]

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/lifecycle stale

[itspngu]

/remove-lifecycle stale

[lreciomelero]

Hi folks! Is it possible to take a look at this issue?

[k8s-triage-robot]

The Kubernetes project currently lacks enough contributors to adequately respond to all issues.

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/lifecycle stale

[itspngu]

/remove-lifecycle stale

[mdbooth]

We would like the same thing in https://github.com/kubernetes-sigs/cluster-api-provider-openstack. IIUC there are 2 constraints here, and neither is provider-specific:

• CAPI only allows us to specify a single control plane endpoint. This is described in InfraCluster in the CAPI book.
• The KubeadmControlPlane can only configure a single control plane endpoint.

I don't believe this can be resolved here, but I'm very interested in a solution.

cc @huxcrux

[bfournie]

I believe this is resolved with #1222 and subsequent changes.

[k8s-triage-robot]

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/lifecycle stale

[k8s-triage-robot]

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/lifecycle rotten

[richardcase]

/remove-lifecycle rotten