Support syncing a set of labels from MachineDeployment/MachineSet/Machine to Nodes

[sidharthsurana]

This issue is to add the capability of defining user defined labels, annotations & taints to be created automatically on the created nodes.

for e.g.: The following MachineSet when realized on any of the provider, should result in the 2 user defined labels latency-sensitive: yes and service-class: gold to be created on the nodes created as part of this machineset.

apiVersion: cluster.k8s.io/v1alpha1
kind: MachineSet
metadata:
  name: gold-workers
spec:
  replicas: 3
  selector:
    matchLabels:
      node-type: worker-node
  template:
    metadata:
      labels:
        node-type: worker-node
    spec:
      metadata:
        labels:
          latency-sensitive: yes
          service-class: gold
      providerConfig:
      ...
      ...

The same mechanics should be extended for annotations as well as taints.

[dgoodwin]

This would be nice, we had to write a little controller ourselves to get those applied.

[derekwaynecarr]

the list of labels, taints, and annotations need to be additive (not authoritative)

[vikaschoudhary16]

@dgoodwin

This would be nice, we had to write a little controller ourselves to get those applied.

Wondering what is the issue in extending existing machine controller in cluster-api to perform this task as well in the reconcile loop?

[roberthbailey]

/assign @hardikdr

[enxebre]

Related to #493 and #658. Also for reference kubernetes/kubernetes#73097

[ncdc]

@hardikdr are you currently working on this?

@sidharthsurana do you believe this is a hard requirement for v1alpha1, or could it slip to v1alpha2?

[sidharthsurana]

@ncdc I don't this is a hard requirement from the cluster-api point of view for the v1alpha1 milestone. Given that individual provider implementations can implement these independently as well. I opened this Issue so that if we can figure out a provider agnostic way of implementing this behavior.