Convert machineSpec.Versions to a pointer

[enxebre]

What this PR does / why we need it:
Convert machineSpec.Versions to a pointer so omitempty does not actually marshals the field since it's optional consistently with Status.Versions.
For use cases where the machine config aka kubelet is managed orthogonally to the machine infra the field in the spec wouldn't trigger a moving forward reconciliation hence it wouldn't be leveraged.

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 #

Special notes for your reviewer:

Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

Release note:

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[ingvagabund]

All consumers of the field will be required to change the field access logic. Their code will start to panic in cases where the Versions field is nil.

[neolit123]

such changes are usually more suited in v1alphaX increments.

[ingvagabund]

/ok-to-test

[ingvagabund]

pkg/controller/machine/machine_controller_test.go:42:			Versions: clusterv1alpha1.MachineVersionInfo{Kubelet: "1.10.3"},
pkg/controller/machineset/machineset_controller_test.go:46:					Versions: clusterv1alpha1.MachineVersionInfo{Kubelet: "1.10.3"},
pkg/controller/machinedeployment/machinedeployment_controller_test.go:62:					Versions: clusterv1alpha1.MachineVersionInfo{Kubelet: "1.10.3"},

as well

[enxebre]

/test pull-cluster-api-test

[ingvagabund]

Fails at https://github.com/kubernetes-sigs/cluster-api/blob/master/pkg/util/util.go#L121

[ingvagabund]

generateTestNodeMachine [1] does not set the Version field. Thus why the IsMaster function fails. It should go like:

func IsMaster(machine *clusterv1.Machine) bool {
	return machine.Spec.Versions != nil && machine.Spec.Versions.ControlPlane != ""
}

[1] https://github.com/kubernetes-sigs/cluster-api/blob/master/cmd/clusterctl/clusterdeployer/clusterdeployer_test.go#L1203-L1209

[davidewatson]

Fixes part of #552

[alvaroaleman]

Sorry, after closing #552 I saw this Pull.

For use cases where the machine config aka kubelet is managed orthogonally to the machine infra the field in the spec wouldn't trigger a moving forward reconciliation hence it wouldn't be leveraged

So the advantage of this PR is basically that we don't store+transmit a field when its not used?

[enxebre]

@alvaroaleman yes, so it's actually omitted when empty

[detiber]

I'm a bit confused why we are replicating the version info between Spec and Status currently? I think the idea of having separate provider implementations that optionally use either the spec and/or the status seems counter-intuitive.

We should probably just standardize on the use of the Spec and then implementations could add their own validating and/or defaulting webhooks to enforce the behavior they expect out of how users and/or controllers interact with the spec field.

[ncdc]

Could someone please summarize the state of this PR & the thinking about it - do we still want this?

[vincepri]

I'm a little concerned on making the field optional for v1alpha1. There are a lot of providers that rely on the versions being populated to check if a node is a control plane or not.

[detiber]

I'm a little concerned on making the field optional for v1alpha1. There are a lot of providers that rely on the versions being populated to check if a node is a control plane or not.

As does the clusterctl workflow

[enxebre]

If we agree on the change I'd say the sooner the better for transitioning. Providers should probably rely on the abstraction https://github.com/kubernetes-sigs/cluster-api/pull/683/files#diff-6c6a7fefe37261e2fa8a010cf9e7ae08R120 so changes are transparent. Other than that I don't have strong opinions for pre/post alpha

[fejta-bot]

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/lifecycle stale

[detiber]

Closing since the v1alpha1 types shouldn't be changed at this point.
/close

[k8s-ci-robot]

@detiber: Closed this PR.

In response to this:

Closing since the v1alpha1 types shouldn't be changed at this point.
/close

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