Support of the namespaceLabelSelector in DefaultEvictor plugin

pkg/framework/plugins/defaultevictor/defaultevictor.go

@@ -25,6 +25,8 @@ import (
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/runtime"
 	utilerrors "k8s.io/apimachinery/pkg/util/errors"
+	clientset "k8s.io/client-go/kubernetes"
+	listersv1 "k8s.io/client-go/listers/core/v1"
 
 	"k8s.io/client-go/tools/cache"
 	"k8s.io/klog/v2"
@@ -220,18 +222,12 @@ func (d *DefaultEvictor) PreEvictionFilter(pod *v1.Pod) bool {
 
 	// check pod by namespace label filter
 	if d.args.NamespaceLabelSelector != nil {
-		indexName := "namespaceWithLabelSelector"
-		indexer, err := getNamespacesListByLabelSelector(indexName, d.args.NamespaceLabelSelector, d.handle)
+		ns, err := getNamespaces(context.TODO(), d.handle.ClientSet(), d.handle.SharedInformerFactory().Core().V1().Namespaces().Lister(), metav1.FormatLabelSelector(d.args.NamespaceLabelSelector))
 		if err != nil {
 			klog.ErrorS(err, "unable to list namespaces", "pod", klog.KObj(pod))
-			return false
-		}
-		objs, err := indexer.ByIndex(indexName, pod.Namespace)
-		if err != nil {
-			klog.ErrorS(err, "unable to list namespaces for namespaceLabelSelector filter in the policy parameter", "pod", klog.KObj(pod))
-			return false
 		}
-		if len(objs) == 0 {
+
+		if _, ok := ns[pod.Namespace]; !ok {
 			klog.InfoS("pod namespace do not match the namespaceLabelSelector filter in the policy parameter", "pod", klog.KObj(pod))
 			return false
 		}
@@ -300,38 +296,40 @@ func getPodIndexerByOwnerRefs(indexName string, handle frameworktypes.Handle) (c
 	return indexer, nil
 }
 
-func getNamespacesListByLabelSelector(indexName string, labelSelector *metav1.LabelSelector, handle frameworktypes.Handle) (cache.Indexer, error) {
-	nsInformer := handle.SharedInformerFactory().Core().V1().Namespaces().Informer()
-	indexer := nsInformer.GetIndexer()
+func getNamespaces(ctx context.Context, client clientset.Interface, nsLister listersv1.NamespaceLister, labelSelector string) (map[string]struct{}, error) {
+	ret := make(map[string]struct{})
+	namespaceSelector, err := labels.Parse(labelSelector)
+	if err != nil {
+		return ret, err
+	}
 
-	// do not reinitialize the indexer, if it's been defined already
-	for name := range indexer.GetIndexers() {
-		if name == indexName {
-			return indexer, nil
-		}
+	var ns []*v1.Namespace
+	// err is defined above
+	if ns, err = nsLister.List(namespaceSelector); err != nil {
+		return ret, err
 	}
 
-	if err := nsInformer.AddIndexers(cache.Indexers{
-		indexName: func(obj interface{}) ([]string, error) {
-			ns, ok := obj.(*v1.Namespace)
-			if !ok {
-				return []string{}, errors.New("unexpected object")
-			}
+	if len(ns) == 0 {
+		klog.V(2).InfoS("Namespace lister returned empty list, now fetch directly")
 
-			selector, err := metav1.LabelSelectorAsSelector(labelSelector)
-			if err != nil {
-				return []string{}, errors.New("could not get selector from label selector")
-			}
-			if labelSelector != nil && !selector.Empty() {
-				if !selector.Matches(labels.Set(ns.Labels)) {
-					return []string{}, nil
-				}
-			}
-			return []string{ns.GetName()}, nil
-		},
-	}); err != nil {
-		return nil, err
+		nItems, err := client.CoreV1().Namespaces().List(ctx, metav1.ListOptions{LabelSelector: labelSelector})
+		if err != nil {
+			return ret, err
+		}
+
+		if nItems == nil || len(nItems.Items) == 0 {
+			return ret, nil
+		}
+
+		for i := range nItems.Items {
+			namespace := nItems.Items[i]
+			ns = append(ns, &namespace)
+		}
 	}
 
-	return indexer, nil
+	for _, n := range ns {
+		ret[n.Name] = struct{}{}
+	}
+
+	return ret, nil
 }