Add kubernetes-version/injectKubernetesVersion to Metadata

[rybnico]

Description of changes:

It would be very helpful to have access to the Kubernetes version specified in a machine's spec.version in the cloud-init/ignition metadata. With this information, it is possible to install Kubernetes version specific resources in cloud-init/ignition.

I used this PR as a template, but I'm not sure if the way to control the injection is particularly elegant.
I would suggest injecting the field without a flag in the default or always passing the value of MetadataSettings completely to cloudinit.NewMetadata so that you don't have to add another argument for each flag.
I would be very happy to receive feedback from the maintainers on this suggestion and would then also carry out the desired implementation.

Testing performed:

We have tested this with the following preKubeadmCommands:

      - MINOR_KUBERNETES_VERSION=$(echo {{ '{{ ds.meta_data.kubernetes_version }}' }} | cut -d. -f1-2 )
      - curl -fsSL https://pkgs.k8s.io/core:/stable:/${MINOR_KUBERNETES_VERSION}/deb/Release.key | gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
      - echo "deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/${MINOR_KUBERNETES_VERSION}/deb/ /" > /etc/apt/sources.list.d/kubernetes.list
      - apt-get update -y
      - TRIMMED_KUBERNETES_VERSION=$(echo {{ '{{ ds.meta_data.kubernetes_version }}' }} | sed 's/\./\\\\./g' | sed 's/^v//')
      - RESOLVED_KUBERNETES_VERSION=$(apt-cache madison kubelet | awk -v VERSION=${TRIMMED_KUBERNETES_VERSION} '$3~ VERSION { print $3 }' | head -n1)
      - apt-get install -y kubelet=${RESOLVED_KUBERNETES_VERSION} kubeadm=${RESOLVED_KUBERNETES_VERSION} kubectl=${RESOLVED_KUBERNETES_VERSION}
      - apt-mark hold kubelet kubeadm kubectl

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[wikkyk]

Could we do without both kubernetesVersion and injectKubernetesVersion? You could set BaseCloudInitData.KubernetesVersionInjection depending on whether kubernetesVersion is unset (say, empty string, or nil pointer).

If not, I would prefer the two args be kept together, like so
func NewMetadata(instanceID, hostname string, injectProviderID bool, injectKubernetesVersion bool, kubernetesVersion string) *Metadata {

[rybnico]

Thanks for your feedback!

I have removed the injectKubernetesVersion field. The kubernetes-version will now be injected into the metadata if spec.version is set on the machine.

I had to add a new argument to NewMetadata because I don't have access to the MachineScope there and don't know of any other way to get the Kubernetes version here.

What do you think of the new, much simpler implementation? I removed the draft flag because I think it is ready now. I have successfully tested the implementation on our infrastructure.

[sonarqubecloud]

Quality Gate failed

Failed conditions
62.5% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud