Cluster-autoscaler: delete empty nodes in bulk

cluster-autoscaler/cluster_autoscaler.go

@@ -79,9 +79,10 @@ var (
 		"Node utilization level, defined as sum of requested resources divided by capacity, below which a node can be considered for scale down")
 	scaleDownTrialInterval = flag.Duration("scale-down-trial-interval", 1*time.Minute,
 		"How often scale down possiblity is check")
-	scanInterval      = flag.Duration("scan-interval", 10*time.Second, "How often cluster is reevaluated for scale up or down")
-	maxNodesTotal     = flag.Int("max-nodes-total", 0, "Maximum number of nodes in all node groups. Cluster autoscaler will not grow the cluster beyond this number.")
-	cloudProviderFlag = flag.String("cloud-provider", "gce", "Cloud provider type. Allowed values: gce, aws")
+	scanInterval           = flag.Duration("scan-interval", 10*time.Second, "How often cluster is reevaluated for scale up or down")
+	maxNodesTotal          = flag.Int("max-nodes-total", 0, "Maximum number of nodes in all node groups. Cluster autoscaler will not grow the cluster beyond this number.")
+	cloudProviderFlag      = flag.String("cloud-provider", "gce", "Cloud provider type. Allowed values: gce, aws")
+	maxEmptyBulkDeleteFlag = flag.Int("max-empty-bulk-delete", 10, "Maximum number of empty nodes that can be deleted at the same time.")
 
 	// AvailableEstimators is a list of available estimators.
 	AvailableEstimators = []string{BasicEstimatorName, BinpackingEstimatorName}
@@ -319,7 +320,8 @@ func run(_ <-chan struct{}) {
 							predicateChecker,
 							podLocationHints,
 							usageTracker,
-							recorder)
+							recorder,
+							*maxEmptyBulkDeleteFlag)
 
 						updateDuration("scaledown", scaleDownStart)
 

cluster-autoscaler/scale_down.go

@@ -120,7 +120,8 @@ func ScaleDown(
 	predicateChecker *simulator.PredicateChecker,
 	oldHints map[string]string,
 	usageTracker *simulator.UsageTracker,
-	recorder kube_record.EventRecorder) (ScaleDownResult, error) {
+	recorder kube_record.EventRecorder,
+	maxEmptyBulkDelete int) (ScaleDownResult, error) {
 
 	now := time.Now()
 	candidates := make([]*kube_api.Node, 0)
@@ -163,6 +164,35 @@ func ScaleDown(
 		return ScaleDownNoUnneeded, nil
 	}
 
+	emptyNodes := simulator.FindEmptyNodesToRemove(candidates, pods)
+	if len(emptyNodes) > 0 {
+		limit := maxEmptyBulkDelete
+		if len(emptyNodes) < limit {
+			limit = len(emptyNodes)
+		}
+		emptyNodes = emptyNodes[:limit]
+		confirmation := make(chan error, len(emptyNodes))
+		for _, node := range emptyNodes {
+			glog.V(0).Infof("Scale-down: removing empty node %s", node.Name)
+			simulator.RemoveNodeFromTracker(usageTracker, node.Name, unneededNodes)
+			go func(nodeToDelete *kube_api.Node) {
+				confirmation <- deleteNodeFromCloudProvider(nodeToDelete, cloudProvider, recorder)
+			}(node)
+		}
+		var finalError error
+		for range emptyNodes {
+			if err := <-confirmation; err != nil {
+				glog.Errorf("Problem with empty node deletion: %v", err)
+				finalError = err
+			}
+		}
+		if finalError == nil {
+			return ScaleDownNodeDeleted, nil
+		} else {
+			return ScaleDownError, fmt.Errorf("failed to delete at least one empty node: %v", finalError)
+		}
+	}
+
 	// We look for only 1 node so new hints may be incomplete.
 	nodesToRemove, _, err := simulator.FindNodesToRemove(candidates, nodes, pods, client, predicateChecker, 1, false,
 		oldHints, usageTracker, time.Now())
@@ -183,23 +213,25 @@ func ScaleDown(
 	glog.V(0).Infof("Scale-down: removing node %s, utilization: %v, pods to reschedule: ", toRemove.Node.Name, utilization,
 		strings.Join(podNames, ","))
 
-	nodeGroup, err := cloudProvider.NodeGroupForNode(toRemove.Node)
-	if err != nil {
-		return ScaleDownError, fmt.Errorf("failed to node group for %s: %v", toRemove.Node.Name, err)
-	}
-	if nodeGroup == nil || reflect.ValueOf(nodeGroup).IsNil() {
-		return ScaleDownError, fmt.Errorf("picked node that doesn't belong to a node group: %s", toRemove.Node.Name)
-	}
-
-	err = nodeGroup.DeleteNodes([]*kube_api.Node{toRemove.Node})
 	simulator.RemoveNodeFromTracker(usageTracker, toRemove.Node.Name, unneededNodes)
-
+	err = deleteNodeFromCloudProvider(toRemove.Node, cloudProvider, recorder)
 	if err != nil {
 		return ScaleDownError, fmt.Errorf("Failed to delete %s: %v", toRemove.Node.Name, err)
 	}
-
-	recorder.Eventf(toRemove.Node, kube_api.EventTypeNormal, "ScaleDown",
-		"node removed by cluster autoscaler")
-
 	return ScaleDownNodeDeleted, nil
 }
+
+func deleteNodeFromCloudProvider(node *kube_api.Node, cloudProvider cloudprovider.CloudProvider, recorder kube_record.EventRecorder) error {
+	nodeGroup, err := cloudProvider.NodeGroupForNode(node)
+	if err != nil {
+		return fmt.Errorf("failed to node group for %s: %v", node.Name, err)
+	}
+	if nodeGroup == nil || reflect.ValueOf(nodeGroup).IsNil() {
+		return fmt.Errorf("picked node that doesn't belong to a node group: %s", node.Name)
+	}
+	if err = nodeGroup.DeleteNodes([]*kube_api.Node{node}); err != nil {
+		return fmt.Errorf("failed to delete %s: %v", node.Name, err)
+	}
+	recorder.Eventf(node, kube_api.EventTypeNormal, "ScaleDown", "node removed by cluster autoscaler")
+	return nil
+}

cluster-autoscaler/simulator/cluster.go

@@ -111,6 +111,30 @@ candidateloop:
 	return result, newHints, nil
 }
 
+// FindEmptyNodesToRemove finds empty nodes that can be removed.
+func FindEmptyNodesToRemove(candidates []*kube_api.Node, pods []*kube_api.Pod) []*kube_api.Node {
+	nodeNameToNodeInfo := schedulercache.CreateNodeNameToInfoMap(pods)
+	for _, node := range candidates {
+		if nodeInfo, found := nodeNameToNodeInfo[node.Name]; found {
+			nodeInfo.SetNode(node)
+		}
+	}
+	result := make([]*kube_api.Node, 0)
+	for _, node := range candidates {
+		if nodeInfo, found := nodeNameToNodeInfo[node.Name]; found {
+			// Should block on all pods.
+			podsToRemove, err := FastGetPodsToMove(nodeInfo, true, true)
+			if err == nil && len(podsToRemove) == 0 {
+				result = append(result, node)
+			}
+		} else {
+			// Node without pods.
+			result = append(result, node)
+		}
+	}
+	return result
+}
+
 // CalculateUtilization calculates utilization of a node, defined as total amount of requested resources divided by capacity.
 func CalculateUtilization(node *kube_api.Node, nodeInfo *schedulercache.NodeInfo) (float64, error) {
 	cpu, err := calculateUtilizationOfResource(node, nodeInfo, kube_api.ResourceCPU)

cluster-autoscaler/simulator/cluster_test.go

@@ -23,6 +23,7 @@ import (
 	. "k8s.io/contrib/cluster-autoscaler/utils/test"
 
 	kube_api "k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/kubelet/types"
 	"k8s.io/kubernetes/plugin/pkg/scheduler/schedulercache"
 
 	"github.com/stretchr/testify/assert"
@@ -150,3 +151,21 @@ func TestShuffleNodes(t *testing.T) {
 	}
 	assert.True(t, gotPermutation)
 }
+
+func TestFindEmptyNodes(t *testing.T) {
+	pod1 := BuildTestPod("p1", 300, 500000)
+	pod1.Spec.NodeName = "n1"
+	pod2 := BuildTestPod("p2", 300, 500000)
+	pod2.Spec.NodeName = "n2"
+	pod2.Annotations = map[string]string{
+		types.ConfigMirrorAnnotationKey: "",
+	}
+
+	node1 := BuildTestNode("n1", 1000, 2000000)
+	node2 := BuildTestNode("n2", 1000, 2000000)
+	node3 := BuildTestNode("n3", 1000, 2000000)
+	node4 := BuildTestNode("n4", 1000, 2000000)
+
+	emptyNodes := FindEmptyNodesToRemove([]*kube_api.Node{node1, node2, node3, node4}, []*kube_api.Pod{pod1, pod2})
+	assert.Equal(t, []*kube_api.Node{node2, node3, node4}, emptyNodes)
+}