Add support for specifying additional subject alternative names for apiserver

[ahmedwaleedmalik]

What this PR does / why we need it:
Add support for specifying additional subject alternative names for apiserver

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #1464

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Option to specify `Subejct Alternative Names` for apiserver

[kron4eg]

/approve

[kron4eg]

/hold

[kron4eg]

@ahmedwaleedmalik sorry, there is one more place (which I've forgot about) where this needs to be integrated. It's parsing from terraform.
We parse APIEndpoint from terraform

kubeone/pkg/terraform/v1beta1/config.go

Line 167 in b6ae859

cluster.APIEndpoint = kubeonev1beta1.APIEndpoint{

so by analogy, please add parsing of additional_names (which you should define in terraform's output.tf).

[kron4eg]

/approve cancel
/lgtm cancel

[kron4eg]

/unhold

[ahmedwaleedmalik]

additional_names

@kron4eg Please check my last commit. I have added something based on my understanding but it's not the right approach imo. Also, the value of SAN is not persisted anywhere in terraform state so this will cause a conflict between what's inputted via tf and KubeOneCluster config.

[kron4eg]

additional_names

it's not the right approach imo.

What’s the right approach in your opinion?

Also, the value of SAN is not persisted anywhere in terraform state

terraform outputs are saved, AFAIK

so this will cause a conflict between what's inputted via tf and KubeOneCluster config.

there’s no conflict but only a precedence. Config will override whatever is given from terraform.

[ahmedwaleedmalik]

Config will override whatever is given from terraform.

This clears my confusion. ✌️

[kron4eg]

/approve

[kubermatic-bot]

LGTM label has been added.

Git tree hash: 58ac66c156f4062e2c7b364d26cef331728349e8

[kubermatic-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ahmedwaleedmalik, kron4eg

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