Merge pull request https://github.com/kubernetes/contrib/pull/1049 from mwielgus/skip-kubernetes-system

Cluster-autoscaler: do not delete nodes with kube-system, not-mirrored, not-daemon set pods

cluster-autoscaler/simulator/cluster.go

@@ -51,7 +51,7 @@ candidateloop:
 
 		if fastCheck {
 			if nodeInfo, found := nodeNameToNodeInfo[node.Name]; found {
-				podsToRemove, err = FastGetPodsToMove(nodeInfo, false, kube_api.Codecs.UniversalDecoder())
+				podsToRemove, err = FastGetPodsToMove(nodeInfo, false, true, kube_api.Codecs.UniversalDecoder())
 			}
 		} else {
 			drainResult, _, _, err := cmd.GetPodsForDeletionOnNodeDrain(client, node.Name,

cluster-autoscaler/simulator/drain.go

@@ -31,7 +31,8 @@ import (
 // Based on kubectl drain code. It makes an assumption that RC, DS, Jobs and RS were deleted
 // along with their pods (no abandoned pods with dangling created-by annotation). Usefull for fast
 // checks.
-func FastGetPodsToMove(nodeInfo *schedulercache.NodeInfo, force bool, decoder runtime.Decoder) ([]*api.Pod, error) {
+func FastGetPodsToMove(nodeInfo *schedulercache.NodeInfo, force bool,
+	failOnKubeSystemAddons bool, decoder runtime.Decoder) ([]*api.Pod, error) {
 	pods := make([]*api.Pod, 0)
 	unreplicatedPodNames := []string{}
 	for _, pod := range nodeInfo.Pods() {
@@ -47,7 +48,7 @@ func FastGetPodsToMove(nodeInfo *schedulercache.NodeInfo, force bool, decoder ru
 		if found {
 			var sr api.SerializedReference
 			if err := runtime.DecodeInto(decoder, []byte(creatorRef), &sr); err != nil {
-				return pods, err
+				return []*api.Pod{}, err
 			}
 			if sr.Reference.Kind == "ReplicationController" {
 				replicated = true
@@ -60,6 +61,10 @@ func FastGetPodsToMove(nodeInfo *schedulercache.NodeInfo, force bool, decoder ru
 			}
 		}
 
+		if !daemonsetPod && pod.Namespace == "kube-system" && failOnKubeSystemAddons {
+			return []*api.Pod{}, fmt.Errorf("non-deamons set, non-mirrored, kube-system pod present: %s", pod.Name)
+		}
+
 		switch {
 		case daemonsetPod:
 			break