Kubeadm remove v1alpha2 api

[fabriziopandini]

What this PR does / why we need it:
This PR removes v1alpha2 API from kubeadm.

Which issue(s) this PR fixes:
Ref: kubernetes/kubeadm#911

Special notes for your reviewer:
This PR is the first of a series or PRs that will remove v1alpha2, cleanup all the references to v1alpha2 objects, and finally add v1beta1 api version; the work is divided into multiple PRs hopefully more easy to review.

This PR leaves some TODOs as a placeholder for implementing v1alpha3-->v1beta1 roundtrip tests in following PRs.

Release note:

[action required] kubeadm: The `v1alpha2` config API has been removed.
Please convert your `v1alpha2` configuration files to `v1alpha3` using the
`kubeadm config migrate` command of kubeadm v1.12.x

@kubernetes/sig-cluster-lifecycle-pr-reviews
sig cluster-lifecycle
kind api-change
area kubeadm

/cc @timothysc @luxas

[neolit123]

thanks @fabriziopandini
i will have a look a bit later.

/kind api-change

[timothysc]

Please merge this with #69056 into a single changeset for v1alpha2 for historical purposes.

[timothysc]

Also can you squash commits to 2.

• removal of v1alpha2
• autogenerated

[fabriziopandini]

Dear k8s ci robot
/test pull-kubernetes-e2e-kops-aws
/test pull-kubernetes-e2e-gce-100-performance

[timothysc]

/lgtm
/approve

Please address the comment, or possibly follow up on a separate PR.

[timothysc]

b/c you are removing alpha 2 should you remove v1.11?

[fabriziopandini]

This piece of code gives warning to user if the pass to kubeadm an older version of the config, and tell what version of kubeadm can be used for executing config migrate.
I think that giving a warning also for v1alpha1 doesn't hurts...

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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This pull-request has been approved by: fabriziopandini, timothysc

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[chuckha]

Is the goal here to have one alpha version and n beta versions?

Seems like removing the v1alpha2 type is just as dangerous as making a breaking change to v1alpha1 like in the 1.10 release. It feels like at this point we'd want to rename v1alpha2 to v1alpha1 and v1alpha3 to v1beta1.

[timothysc]

@chuckha - It's explicitly stated that the support model for kubeadm needs to upgrade through. So a 1.11 version can only upgrade from 1.10. Maintaining code and machinery of past versions (that aren't supported) is an albatross so we continually shed the code every cycle.

[chuckha]

@timothysc right, I get that, but if I'm reading this right, we're getting rid of the newer version (v1alpha2) and keeping the older one (v1alpha1), I'd suggest renaming v1alpha2 to v1alpha1 and getting rid of the current v1alpha1.

[neolit123]

@fabriziopandini
LGTM

@chuckha @timothysc

Seems like removing the v1alpha2 type is just as dangerous as making a breaking change to v1alpha1 like in the 1.10 release

i know that removing v1alpha1 early in the 1.12 cycle broke kubernetes-anywhere because config --migrate no longer worked on master and we no longer supported the old config.

this early removal method, forced us to handle versions in bash, which is a bad outcome:
https://github.com/kubernetes/kubernetes-anywhere/blob/master/phase2/kubeadm/configure-vm-kubeadm-master.sh

i will send a PR for k-a, because i'm pretty sure this PR will make the master tests red.

[fabriziopandini]

@chuckha

I get that, but if I'm reading this right, we're getting rid of the newer version (v1alpha2) and keeping the older one (v1alpha1)

Current version is v1alpha3; this PR is getting rid of v1alpha2
Soonish I will add v1beta1 and all the machinery for converting v1alpha3->v1beta1

@neolit123

i will send a PR for k-a, because i'm pretty sire this PR will make the master tests red.

Thanks. We can make k/a use v1alpha3 for kubeadm v>=1.12

[timothysc]

/test pull-kubernetes-integration
/test pull-kubernetes-e2e-kops-aws