Force preempting system-node-critical daemon sets

cluster-autoscaler/simulator/node_info_utils.go

@@ -148,23 +148,34 @@ func podsExpectedOnFreshNode(sanitizedExampleNodeInfo *framework.NodeInfo, daemo
 	// TODO(DRA): Figure out how to make this work for DS pods using DRA. Currently such pods would get force-added to the
 	// ClusterSnapshot, but the ResourceClaims reflecting their DRA usage on the Node wouldn't. So CA would be overestimating
 	// available DRA resources on the Node.
-	if forceDaemonSets {
-		var pendingDS []*appsv1.DaemonSet
-		for _, ds := range daemonsets {
-			if !runningDS[ds.UID] {
-				pendingDS = append(pendingDS, ds)
-			}
+	var pendingDS []*appsv1.DaemonSet
+	for _, ds := range daemonsets {
+		if !runningDS[ds.UID] {
+			pendingDS = append(pendingDS, ds)
 		}
-		// The provided nodeInfo has to have taints properly sanitized, or this won't work correctly.
-		daemonPods, err := daemonset.GetDaemonSetPodsForNode(sanitizedExampleNodeInfo, pendingDS)
-		if err != nil {
-			return nil, err
-		}
-		for _, pod := range daemonPods {
-			// There's technically no need to sanitize these pods since they're created from scratch, but
-			// it's nice to have the same suffix for all names in one sanitized NodeInfo when debugging.
-			result = append(result, &framework.PodInfo{Pod: createSanitizedPod(pod.Pod, sanitizedExampleNodeInfo.Node().Name, nameSuffix)})
+	}
+	// The provided nodeInfo has to have taints properly sanitized, or this won't work correctly.
+	daemonPods, err := daemonset.GetDaemonSetPodsForNode(sanitizedExampleNodeInfo, pendingDS)
+	if err != nil {
+		return nil, err
+	}
+	for _, pod := range daemonPods {
+		if !forceDaemonSets && !isPreemptingSystemNodeCritical(pod) {
+			continue
 		}
+		// There's technically no need to sanitize these pods since they're created from scratch, but
+		// it's nice to have the same suffix for all names in one sanitized NodeInfo when debugging.
+		result = append(result, &framework.PodInfo{Pod: createSanitizedPod(pod.Pod, sanitizedExampleNodeInfo.Node().Name, nameSuffix)})
 	}
 	return result, nil
 }
+
+func isPreemptingSystemNodeCritical(pod *framework.PodInfo) bool {
+	if pod.Spec.PriorityClassName != labels.SystemNodeCriticalLabel {
+		return false
+	}
+	if pod.Spec.PreemptionPolicy != nil && *pod.Spec.PreemptionPolicy != apiv1.PreemptLowerPriority {
+		return false
+	}
+	return true
+}

cluster-autoscaler/simulator/node_info_utils_test.go

@@ -31,13 +31,15 @@ import (
 	resourceapi "k8s.io/api/resource/v1beta1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/kubernetes/pkg/controller/daemon"
+
 	"k8s.io/autoscaler/cluster-autoscaler/config"
 	drautils "k8s.io/autoscaler/cluster-autoscaler/simulator/dynamicresources/utils"
 	"k8s.io/autoscaler/cluster-autoscaler/simulator/framework"
 	"k8s.io/autoscaler/cluster-autoscaler/utils/errors"
+	"k8s.io/autoscaler/cluster-autoscaler/utils/labels"
 	"k8s.io/autoscaler/cluster-autoscaler/utils/taints"
 	. "k8s.io/autoscaler/cluster-autoscaler/utils/test"
-	"k8s.io/kubernetes/pkg/controller/daemon"
 )
 
 var (
@@ -69,7 +71,21 @@ var (
 			},
 		},
 	}
-	testDaemonSets = []*appsv1.DaemonSet{ds1, ds2, ds3}
+	ds4 = &appsv1.DaemonSet{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      "ds4",
+			Namespace: "ds4-namespace",
+			UID:       types.UID("ds4"),
+		},
+		Spec: appsv1.DaemonSetSpec{
+			Template: apiv1.PodTemplateSpec{
+				Spec: apiv1.PodSpec{
+					PriorityClassName: labels.SystemNodeCriticalLabel,
+				},
+			},
+		},
+	}
+	testDaemonSets = []*appsv1.DaemonSet{ds1, ds2, ds3, ds4}
 )
 
 func TestSanitizedTemplateNodeInfoFromNodeGroup(t *testing.T) {
@@ -98,6 +114,7 @@ func TestSanitizedTemplateNodeInfoFromNodeGroup(t *testing.T) {
 			wantPods: []*apiv1.Pod{
 				buildDSPod(ds1, "n"),
 				buildDSPod(ds2, "n"),
+				buildDSPod(ds4, "n"),
 			},
 		},
 		{
@@ -116,6 +133,7 @@ func TestSanitizedTemplateNodeInfoFromNodeGroup(t *testing.T) {
 				SetMirrorPodSpec(BuildScheduledTestPod("p3", 100, 1, "n")),
 				buildDSPod(ds1, "n"),
 				buildDSPod(ds2, "n"),
+				buildDSPod(ds4, "n"),
 			},
 		},
 	} {
@@ -208,6 +226,7 @@ func TestSanitizedTemplateNodeInfoFromNodeInfo(t *testing.T) {
 			daemonSets: testDaemonSets,
 			wantPods: []*apiv1.Pod{
 				buildDSPod(ds1, "n"),
+				buildDSPod(ds4, "n"),
 			},
 		},
 		{
@@ -232,6 +251,7 @@ func TestSanitizedTemplateNodeInfoFromNodeInfo(t *testing.T) {
 			wantPods: []*apiv1.Pod{
 				buildDSPod(ds1, "n"),
 				buildDSPod(ds2, "n"),
+				buildDSPod(ds4, "n"),
 			},
 		},
 		{
@@ -248,6 +268,7 @@ func TestSanitizedTemplateNodeInfoFromNodeInfo(t *testing.T) {
 			wantPods: []*apiv1.Pod{
 				SetMirrorPodSpec(BuildScheduledTestPod("p3", 100, 1, "n")),
 				buildDSPod(ds1, "n"),
+				buildDSPod(ds4, "n"),
 			},
 		},
 		{
@@ -266,6 +287,7 @@ func TestSanitizedTemplateNodeInfoFromNodeInfo(t *testing.T) {
 				SetMirrorPodSpec(BuildScheduledTestPod("p3", 100, 1, "n")),
 				buildDSPod(ds1, "n"),
 				buildDSPod(ds2, "n"),
+				buildDSPod(ds4, "n"),
 			},
 		},
 	}

cluster-autoscaler/utils/labels/labels.go

@@ -25,6 +25,11 @@ import (
 	"k8s.io/apimachinery/pkg/api/resource"
 )
 
+const (
+	// SystemNodeCriticalLabel is a label that marks critical pods with the highest priority.
+	SystemNodeCriticalLabel = "system-node-critical"
+)
+
 var (
 	// cpu amount used for account pods that don't specify cpu requests
 	defaultMinCPU        = *resource.NewMilliQuantity(50, resource.DecimalSI)