skip eviction when replica count is below evictor minReplicas thres…

…hold setting

README.md

@@ -141,6 +141,7 @@ The Default Evictor Plugin is used by default for filtering pods before processi
 |`labelSelector`|`metav1.LabelSelector`||(see [label filtering](#label-filtering))|
 |`priorityThreshold`|`priorityThreshold`||(see [priority filtering](#priority-filtering))|
 |`nodeFit`|`bool`|`false`|(see [node fit filtering](#node-fit-filtering))|
+|`minReplicas`|`uint`|`0`| ignore eviction of pods where owner (e.g. Deployment) replicas is below this threshold |
 
 ### Example policy
 
@@ -165,6 +166,7 @@ profiles:
         evictFailedBarePods: true
         evictLocalStoragePods: true
         nodeFit: true
+        minReplicas: 2
     plugins:
       # DefaultEvictor is enabled for both `filter` and `preEvictionFilter`
       # filter:

go.mod

@@ -12,6 +12,7 @@ require (
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.10.0
 	go.opentelemetry.io/otel/sdk v1.10.0
 	go.opentelemetry.io/otel/trace v1.10.0
+	golang.org/x/exp v0.0.0-20220722155223-a9213eeb770e
 	google.golang.org/grpc v1.54.0
 	k8s.io/api v0.28.0
 	k8s.io/apimachinery v0.28.0
@@ -87,7 +88,6 @@ require (
 	go.uber.org/multierr v1.11.0 // indirect
 	go.uber.org/zap v1.19.0 // indirect
 	golang.org/x/crypto v0.11.0 // indirect
-	golang.org/x/exp v0.0.0-20220722155223-a9213eeb770e // indirect
 	golang.org/x/mod v0.10.0 // indirect
 	golang.org/x/net v0.13.0 // indirect
 	golang.org/x/oauth2 v0.8.0 // indirect

pkg/descheduler/pod/pods.go

@@ -19,6 +19,7 @@ package pod
 import (
 	"sort"
 
+	"golang.org/x/exp/slices"
 	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/labels"
@@ -257,3 +258,20 @@ func SortPodsBasedOnAge(pods []*v1.Pod) {
 		return pods[i].CreationTimestamp.Before(&pods[j].CreationTimestamp)
 	})
 }
+
+// GetOwnerReplicasCount returns the count of pods that match the owner ref of the given pod
+func GetOwnerReplicasCount(pods []*v1.Pod, pod *v1.Pod) uint {
+	var count uint
+	podOwnerRefs := OwnerRef(pod)
+	for _, otherPod := range pods {
+		otherOwnerRefs := OwnerRef(otherPod)
+
+		if slices.EqualFunc(podOwnerRefs, otherOwnerRefs, func(l, r metav1.OwnerReference) bool {
+			return l.UID == r.UID
+		}) {
+			count++
+		}
+	}
+
+	return count
+}

pkg/framework/plugins/defaultevictor/defaultevictor.go

@@ -143,6 +143,21 @@ func New(args runtime.Object, handle frameworktypes.Handle) (frameworktypes.Plug
 		})
 	}
 
+	if defaultEvictorArgs.MinReplicas > 1 {
+		podLister := handle.SharedInformerFactory().Core().V1().Pods().Lister()
+		ev.constraints = append(ev.constraints, func(pod *v1.Pod) error {
+			pods, err := podLister.Pods(pod.Namespace).List(labels.Everything())
+			if err != nil {
+				return fmt.Errorf("unable to list pods for minReplicas filter in the policy parameter")
+			}
+			ownerReplicas := podutil.GetOwnerReplicasCount(pods, pod)
+			if ownerReplicas < defaultEvictorArgs.MinReplicas {
+				return fmt.Errorf("owner has %d replicas which is less than minReplicas of %d", ownerReplicas, defaultEvictorArgs.MinReplicas)
+			}
+			return nil
+		})
+	}
+
 	return ev, nil
 }
 

pkg/framework/plugins/defaultevictor/defaultevictor_test.go

@@ -372,6 +372,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 		evictSystemCriticalPods bool
 		priorityThreshold       *int32
 		nodeFit                 bool
+		minReplicas             uint
 		result                  bool
 	}
 
@@ -527,7 +528,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			evictSystemCriticalPods: false,
 			result:                  true,
 		}, {
-			description: "Pod not evicted becasuse it is part of a daemonSet",
+			description: "Pod not evicted because it is part of a daemonSet",
 			pods: []*v1.Pod{
 				test.BuildTestPod("p8", 400, 0, n1.Name, func(pod *v1.Pod) {
 					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
@@ -538,7 +539,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			evictSystemCriticalPods: false,
 			result:                  false,
 		}, {
-			description: "Pod is evicted becasuse it is part of a daemonSet, but it has scheduler.alpha.kubernetes.io/evict annotation",
+			description: "Pod is evicted because it is part of a daemonSet, but it has scheduler.alpha.kubernetes.io/evict annotation",
 			pods: []*v1.Pod{
 				test.BuildTestPod("p9", 400, 0, n1.Name, func(pod *v1.Pod) {
 					pod.Annotations = map[string]string{"descheduler.alpha.kubernetes.io/evict": "true"}
@@ -549,7 +550,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			evictSystemCriticalPods: false,
 			result:                  true,
 		}, {
-			description: "Pod not evicted becasuse it is a mirror poddsa",
+			description: "Pod not evicted because it is a mirror poddsa",
 			pods: []*v1.Pod{
 				test.BuildTestPod("p10", 400, 0, n1.Name, func(pod *v1.Pod) {
 					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
@@ -560,7 +561,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			evictSystemCriticalPods: false,
 			result:                  false,
 		}, {
-			description: "Pod is evicted becasuse it is a mirror pod, but it has scheduler.alpha.kubernetes.io/evict annotation",
+			description: "Pod is evicted because it is a mirror pod, but it has scheduler.alpha.kubernetes.io/evict annotation",
 			pods: []*v1.Pod{
 				test.BuildTestPod("p11", 400, 0, n1.Name, func(pod *v1.Pod) {
 					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
@@ -572,7 +573,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			evictSystemCriticalPods: false,
 			result:                  true,
 		}, {
-			description: "Pod not evicted becasuse it has system critical priority",
+			description: "Pod not evicted because it has system critical priority",
 			pods: []*v1.Pod{
 				test.BuildTestPod("p12", 400, 0, n1.Name, func(pod *v1.Pod) {
 					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
@@ -584,7 +585,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			evictSystemCriticalPods: false,
 			result:                  false,
 		}, {
-			description: "Pod is evicted becasuse it has system critical priority, but it has scheduler.alpha.kubernetes.io/evict annotation",
+			description: "Pod is evicted because it has system critical priority, but it has scheduler.alpha.kubernetes.io/evict annotation",
 			pods: []*v1.Pod{
 				test.BuildTestPod("p13", 400, 0, n1.Name, func(pod *v1.Pod) {
 					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
@@ -599,7 +600,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			evictSystemCriticalPods: false,
 			result:                  true,
 		}, {
-			description: "Pod not evicted becasuse it has a priority higher than the configured priority threshold",
+			description: "Pod not evicted because it has a priority higher than the configured priority threshold",
 			pods: []*v1.Pod{
 				test.BuildTestPod("p14", 400, 0, n1.Name, func(pod *v1.Pod) {
 					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
@@ -611,7 +612,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			priorityThreshold:       &lowPriority,
 			result:                  false,
 		}, {
-			description: "Pod is evicted becasuse it has a priority higher than the configured priority threshold, but it has scheduler.alpha.kubernetes.io/evict annotation",
+			description: "Pod is evicted because it has a priority higher than the configured priority threshold, but it has scheduler.alpha.kubernetes.io/evict annotation",
 			pods: []*v1.Pod{
 				test.BuildTestPod("p15", 400, 0, n1.Name, func(pod *v1.Pod) {
 					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
@@ -624,7 +625,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			priorityThreshold:       &lowPriority,
 			result:                  true,
 		}, {
-			description: "Pod is evicted becasuse it has system critical priority, but evictSystemCriticalPods = true",
+			description: "Pod is evicted because it has system critical priority, but evictSystemCriticalPods = true",
 			pods: []*v1.Pod{
 				test.BuildTestPod("p16", 400, 0, n1.Name, func(pod *v1.Pod) {
 					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
@@ -636,7 +637,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			evictSystemCriticalPods: true,
 			result:                  true,
 		}, {
-			description: "Pod is evicted becasuse it has system critical priority, but evictSystemCriticalPods = true and it has scheduler.alpha.kubernetes.io/evict annotation",
+			description: "Pod is evicted because it has system critical priority, but evictSystemCriticalPods = true and it has scheduler.alpha.kubernetes.io/evict annotation",
 			pods: []*v1.Pod{
 				test.BuildTestPod("p16", 400, 0, n1.Name, func(pod *v1.Pod) {
 					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
@@ -649,7 +650,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			evictSystemCriticalPods: true,
 			result:                  true,
 		}, {
-			description: "Pod is evicted becasuse it has a priority higher than the configured priority threshold, but evictSystemCriticalPods = true",
+			description: "Pod is evicted because it has a priority higher than the configured priority threshold, but evictSystemCriticalPods = true",
 			pods: []*v1.Pod{
 				test.BuildTestPod("p17", 400, 0, n1.Name, func(pod *v1.Pod) {
 					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
@@ -661,7 +662,7 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			priorityThreshold:       &lowPriority,
 			result:                  true,
 		}, {
-			description: "Pod is evicted becasuse it has a priority higher than the configured priority threshold, but evictSystemCriticalPods = true and it has scheduler.alpha.kubernetes.io/evict annotation",
+			description: "Pod is evicted because it has a priority higher than the configured priority threshold, but evictSystemCriticalPods = true and it has scheduler.alpha.kubernetes.io/evict annotation",
 			pods: []*v1.Pod{
 				test.BuildTestPod("p17", 400, 0, n1.Name, func(pod *v1.Pod) {
 					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
@@ -704,6 +705,30 @@ func TestDefaultEvictorFilter(t *testing.T) {
 			evictSystemCriticalPods: false,
 			nodeFit:                 true,
 			result:                  true,
+		}, {
+			description: "minReplicas of 2, owner with 2 replicas, evicts",
+			pods: []*v1.Pod{
+				test.BuildTestPod("p1", 1, 1, n1.Name, func(pod *v1.Pod) {
+					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
+				}),
+				test.BuildTestPod("p2", 1, 1, n1.Name, func(pod *v1.Pod) {
+					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
+				}),
+			},
+			minReplicas: 2,
+			result:      true,
+		}, {
+			description: "minReplicas of 3, owner with 2 replicas, no eviction",
+			pods: []*v1.Pod{
+				test.BuildTestPod("p1", 1, 1, n1.Name, func(pod *v1.Pod) {
+					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
+				}),
+				test.BuildTestPod("p2", 1, 1, n1.Name, func(pod *v1.Pod) {
+					pod.ObjectMeta.OwnerReferences = test.GetNormalPodOwnerRefList()
+				}),
+			},
+			minReplicas: 3,
+			result:      false,
 		},
 	}
 
@@ -741,7 +766,8 @@ func TestDefaultEvictorFilter(t *testing.T) {
 				PriorityThreshold: &api.PriorityThreshold{
 					Value: test.priorityThreshold,
 				},
-				NodeFit: test.nodeFit,
+				NodeFit:     test.nodeFit,
+				MinReplicas: test.minReplicas,
 			}
 
 			evictorPlugin, err := New(

pkg/framework/plugins/defaultevictor/types.go

@@ -33,4 +33,5 @@ type DefaultEvictorArgs struct {
 	LabelSelector           *metav1.LabelSelector  `json:"labelSelector"`
 	PriorityThreshold       *api.PriorityThreshold `json:"priorityThreshold"`
 	NodeFit                 bool                   `json:"nodeFit"`
+	MinReplicas             uint                   `json:"minReplicas"`
 }

test/e2e/e2e_duplicatepods_test.go

@@ -107,6 +107,7 @@ func TestRemoveDuplicates(t *testing.T) {
 		replicasNum             int
 		beforeFunc              func(deployment *appsv1.Deployment)
 		expectedEvictedPodCount uint
+		minReplicas             uint
 	}{
 		{
 			description: "Evict Pod even Pods schedule to specific node",
@@ -135,6 +136,15 @@ func TestRemoveDuplicates(t *testing.T) {
 			},
 			expectedEvictedPodCount: 2,
 		},
+		{
+			description: "Ignores eviction with minReplicas of 4",
+			replicasNum: 3,
+			beforeFunc: func(deployment *appsv1.Deployment) {
+				deployment.Spec.Replicas = pointer.Int32(3)
+			},
+			expectedEvictedPodCount: 0,
+			minReplicas:             4,
+		},
 	}
 	for _, tc := range tests {
 		t.Run(tc.description, func(t *testing.T) {
@@ -179,6 +189,7 @@ func TestRemoveDuplicates(t *testing.T) {
 				IgnorePvcPods:           false,
 				EvictFailedBarePods:     false,
 				NodeFit:                 false,
+				MinReplicas:             tc.minReplicas,
 			}
 
 			evictorFilter, err := defaultevictor.New(