Migrate RemovePodsViolatingInterPodAntiAffinity into a plugin

pkg/framework/plugins/removepodsviolatinginterpodantiaffinity/pod_antiaffinity.go

@@ -0,0 +1,143 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package removepodsviolatinginterpodantiaffinity
+
+import (
+	"context"
+	"fmt"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/util/sets"
+	"sigs.k8s.io/descheduler/pkg/apis/componentconfig"
+	"sigs.k8s.io/descheduler/pkg/descheduler/evictions"
+	podutil "sigs.k8s.io/descheduler/pkg/descheduler/pod"
+	"sigs.k8s.io/descheduler/pkg/framework"
+	"sigs.k8s.io/descheduler/pkg/utils"
+
+	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/klog/v2"
+)
+
+const PluginName = "RemovePodsViolatingInterPodAntiAffinity"
+
+// RemovePodsViolatingInterPodAntiAffinity evicts pods on the node which violate inter pod anti affinity
+type RemovePodsViolatingInterPodAntiAffinity struct {
+	handle    framework.Handle
+	args      *componentconfig.RemovePodsViolatingInterPodAntiAffinityArgs
+	podFilter podutil.FilterFunc
+}
+
+var _ framework.Plugin = &RemovePodsViolatingInterPodAntiAffinity{}
+var _ framework.DeschedulePlugin = &RemovePodsViolatingInterPodAntiAffinity{}
+
+// New builds plugin from its arguments while passing a handle
+func New(args runtime.Object, handle framework.Handle) (framework.Plugin, error) {
+	interPodAntiAffinityArgs, ok := args.(*componentconfig.RemovePodsViolatingInterPodAntiAffinityArgs)
+	if !ok {
+		return nil, fmt.Errorf("want args to be of type RemovePodsViolatingInterPodAntiAffinityArgs, got %T", args)
+	}
+
+	var includedNamespaces, excludedNamespaces sets.String
+	if interPodAntiAffinityArgs.Namespaces != nil {
+		includedNamespaces = sets.NewString(interPodAntiAffinityArgs.Namespaces.Include...)
+		excludedNamespaces = sets.NewString(interPodAntiAffinityArgs.Namespaces.Exclude...)
+	}
+
+	podFilter, err := podutil.NewOptions().
+		WithNamespaces(includedNamespaces).
+		WithoutNamespaces(excludedNamespaces).
+		WithLabelSelector(interPodAntiAffinityArgs.LabelSelector).
+		BuildFilterFunc()
+	if err != nil {
+		return nil, fmt.Errorf("error initializing pod filter function: %v", err)
+	}
+
+	return &RemovePodsViolatingInterPodAntiAffinity{
+		handle:    handle,
+		podFilter: podFilter,
+		args:      interPodAntiAffinityArgs,
+	}, nil
+}
+
+// Name retrieves the plugin name
+func (d *RemovePodsViolatingInterPodAntiAffinity) Name() string {
+	return PluginName
+}
+
+func (d *RemovePodsViolatingInterPodAntiAffinity) Deschedule(ctx context.Context, nodes []*v1.Node) *framework.Status {
+loop:
+	for _, node := range nodes {
+		klog.V(1).InfoS("Processing node", "node", klog.KObj(node))
+		pods, err := podutil.ListPodsOnANode(node.Name, d.handle.GetPodsAssignedToNodeFunc(), d.podFilter)
+		if err != nil {
+			return &framework.Status{
+				Err: fmt.Errorf("error listing pods: %v", err),
+			}
+		}
+		// sort the evictable Pods based on priority, if there are multiple pods with same priority, they are sorted based on QoS tiers.
+		podutil.SortPodsBasedOnPriorityLowToHigh(pods)
+		totalPods := len(pods)
+		for i := 0; i < totalPods; i++ {
+			if checkPodsWithAntiAffinityExist(pods[i], pods) && d.handle.Evictor().Filter(pods[i]) {
+				if d.handle.Evictor().Evict(ctx, pods[i], evictions.EvictOptions{}) {
+					// Since the current pod is evicted all other pods which have anti-affinity with this
+					// pod need not be evicted.
+					// Update pods.
+					pods = append(pods[:i], pods[i+1:]...)
+					i--
+					totalPods--
+				}
+			}
+			if d.handle.Evictor().NodeLimitExceeded(node) {
+				continue loop
+			}
+		}
+	}
+	return nil
+}
+
+// checkPodsWithAntiAffinityExist checks if there are other pods on the node that the current pod cannot tolerate.
+func checkPodsWithAntiAffinityExist(pod *v1.Pod, pods []*v1.Pod) bool {
+	affinity := pod.Spec.Affinity
+	if affinity != nil && affinity.PodAntiAffinity != nil {
+		for _, term := range getPodAntiAffinityTerms(affinity.PodAntiAffinity) {
+			namespaces := utils.GetNamespacesFromPodAffinityTerm(pod, &term)
+			selector, err := metav1.LabelSelectorAsSelector(term.LabelSelector)
+			if err != nil {
+				klog.ErrorS(err, "Unable to convert LabelSelector into Selector")
+				return false
+			}
+			for _, existingPod := range pods {
+				if existingPod.Name != pod.Name && utils.PodMatchesTermsNamespaceAndSelector(existingPod, namespaces, selector) {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}
+
+// getPodAntiAffinityTerms gets the antiaffinity terms for the given pod.
+func getPodAntiAffinityTerms(podAntiAffinity *v1.PodAntiAffinity) (terms []v1.PodAffinityTerm) {
+	if podAntiAffinity != nil {
+		if len(podAntiAffinity.RequiredDuringSchedulingIgnoredDuringExecution) != 0 {
+			terms = podAntiAffinity.RequiredDuringSchedulingIgnoredDuringExecution
+		}
+	}
+	return terms
+}