Exclude Master and ExcludeBalancer nodes from Instance Groups

[lbernail]

The list of nodes added to instance groups is not consistent with the service controller.

In the service controller, when calling ensureLoadBalancer the node list provided to the cloud controller is built without Master and ExcludeBalancer nodes (with the feature gate ServiceNodeExclusion). Labels filtered out are node-role.kubernetes.io/master and alpha.service-controller.kubernetes.io/exclude-balancer. See function getNodeConditionPredicate:

https://github.com/kubernetes/kubernetes/blob/97fdf8ac70dfdaf07074dee6b6cb345be71e96ec/pkg/controller/service/service_controller.go#L585

This function then filters out nodes that are not ready.

In GCE, the load-balancer controller then creates instance groups based on these nodes.

However the logic is different in the ingress-gce controller: the getReadyNodeNames function lists Ready nodes and filters out Unschedulable nodes:

ingress-gce/pkg/controller/utils.go

Line 202 in 5642218

func getReadyNodeNames(lister listers.NodeLister) ([]string, error) {

This is an issue for us because we want to use both Internal Load Balancers and GCLB ingress and the list of nodes do not match (we run Kubernetes on GCE and we have kubelets on masters). In addition, our masters are behind an ILB and the ingress controller can't add them to instance groups because they are already part of load-balanced one.

If this makes sense, I'm happy to provide a PR.

[lbernail]

I've just realized that this is a duplicate of #292
(I discovered the issue with @octplane earlier and did not recheck the issues before submitting)

I'm keeping it opened if you want some context on why this is an issue for us but feel free to close it