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Check whether pod matches the inter-pod anti-affinity of another Pod in a given Node in NodeFit() (#1356)

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* Check if Pod matches inter-pod anti-affinity of other pod on node as part of NodeFit()

* Add unit tests for checking inter-pod anti-affinity match in NodeFit()
* Export setPodAntiAffinity() helper func to test utils

* Add docs for inter-pod anti-affinity in README

* Refactor logic for inter-pod anti-affinity to use in multiple pkgs
* Move logic for finding match between pods with antiaffinity out of framework to reuse in other pkgs
* Move interpod antiaffinity funcs to pkg/utils/predicates.go

* Add unit tests for inter-pod anti-affinity check
* Test logic in GroupByNodeName
* Test NodeFit() case where pods matches inter-pod anti-affinity
* Test for inter-pod anti-affinity pods  match terms, have label selector

* NodeFit inter-pod anti-affinity check returns early if affinity spec not set
This commit is contained in:
Niki Manoledaki
2024-03-13 03:50:03 +01:00
committed by GitHub
parent dc2cf723bc
commit 749e81c51c
12 changed files with 328 additions and 132 deletions
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109
pkg/framework/plugins/removepodsviolatinginterpodantiaffinity/pod_antiaffinity.go
View File

@@ -28,7 +28,6 @@ import (
"sigs.k8s.io/descheduler/pkg/utils"
v1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/klog/v2"
)
@@ -86,8 +85,8 @@ func (d *RemovePodsViolatingInterPodAntiAffinity) Deschedule(ctx context.Context
}
podsInANamespace := podutil.GroupByNamespace(pods)
podsOnANode := groupByNodeName(pods)
nodeMap := createNodeMap(nodes)
podsOnANode := podutil.GroupByNodeName(pods)
nodeMap := utils.CreateNodeMap(nodes)
loop:
for _, node := range nodes {
@@ -97,15 +96,17 @@ loop:
podutil.SortPodsBasedOnPriorityLowToHigh(pods)
totalPods := len(pods)
for i := 0; i < totalPods; i++ {
if checkPodsWithAntiAffinityExist(pods[i], podsInANamespace, nodeMap) && d.handle.Evictor().Filter(pods[i]) && d.handle.Evictor().PreEvictionFilter(pods[i]) {
if d.handle.Evictor().Evict(ctx, pods[i], evictions.EvictOptions{StrategyName: PluginName}) {
// Since the current pod is evicted all other pods which have anti-affinity with this
// pod need not be evicted.
// Update allPods.
podsInANamespace = removePodFromNamespaceMap(pods[i], podsInANamespace)
pods = append(pods[:i], pods[i+1:]...)
i--
totalPods--
if utils.CheckPodsWithAntiAffinityExist(pods[i], podsInANamespace, nodeMap) {
if d.handle.Evictor().Filter(pods[i]) && d.handle.Evictor().PreEvictionFilter(pods[i]) {
if d.handle.Evictor().Evict(ctx, pods[i], evictions.EvictOptions{StrategyName: PluginName}) {
// Since the current pod is evicted all other pods which have anti-affinity with this
// pod need not be evicted.
// Update allPods.
podsInANamespace = removePodFromNamespaceMap(pods[i], podsInANamespace)
pods = append(pods[:i], pods[i+1:]...)
i--
totalPods--
}
}
}
if d.handle.Evictor().NodeLimitExceeded(node) {
@@ -130,87 +131,3 @@ func removePodFromNamespaceMap(podToRemove *v1.Pod, podMap map[string][]*v1.Pod)
}
return podMap
}
func groupByNodeName(pods []*v1.Pod) map[string][]*v1.Pod {
m := make(map[string][]*v1.Pod)
for i := 0; i < len(pods); i++ {
pod := pods[i]
m[pod.Spec.NodeName] = append(m[pod.Spec.NodeName], pod)
}
return m
}
func createNodeMap(nodes []*v1.Node) map[string]*v1.Node {
m := make(map[string]*v1.Node, len(nodes))
for _, node := range nodes {
m[node.GetName()] = node
}
return m
}
// checkPodsWithAntiAffinityExist checks if there are other pods on the node that the current pod cannot tolerate.
func checkPodsWithAntiAffinityExist(pod *v1.Pod, pods map[string][]*v1.Pod, nodeMap map[string]*v1.Node) 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 namespace := range namespaces {
for _, existingPod := range pods[namespace] {
if existingPod.Name != pod.Name && utils.PodMatchesTermsNamespaceAndSelector(existingPod, namespaces, selector) {
node, ok := nodeMap[pod.Spec.NodeName]
if !ok {
continue
}
nodeHavingExistingPod, ok := nodeMap[existingPod.Spec.NodeName]
if !ok {
continue
}
if hasSameLabelValue(node, nodeHavingExistingPod, term.TopologyKey) {
klog.V(1).InfoS("Found Pods violating PodAntiAffinity", "pod to evicted", klog.KObj(pod))
return true
}
}
}
}
}
}
return false
}
func hasSameLabelValue(node1, node2 *v1.Node, key string) bool {
if node1.Name == node2.Name {
return true
}
node1Labels := node1.Labels
if node1Labels == nil {
return false
}
node2Labels := node2.Labels
if node2Labels == nil {
return false
}
value1, ok := node1Labels[key]
if !ok {
return false
}
value2, ok := node2Labels[key]
if !ok {
return false
}
return value1 == value2
}
// 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
}