nodes := &corev1.NodeList{}
  opts := &client.ListOptions{}
  if err := opts.SetFieldSelector("spec.unschedulable=true"); err != nil {
    reqLogger.Info("Failed to set field selector")
  }

2019-04-23T10:19:39.761-0700    ERROR   kubebuilder.controller  Reconciler error    {"controller": "node-controller", "request": "/nodename", "error": "Index with name field:spec.unschedulable does not exist"}

kubectl get nodes --field-selector="spec.unschedulable=true"