Replace anti-affinity with topology spread

Co-authored-by: Johannes Dillmann <[email protected]>
cloudfoundry · Sep 25, 2024 · ade9d79 · ade9d79
1 parent 96c77ac
commit ade9d79
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Showing 3 changed files with 31 additions and 42 deletions.
diff --git a/statefulset-runner/controllers/appworkload_controller.go b/statefulset-runner/controllers/appworkload_controller.go
@@ -61,8 +61,6 @@ const (
 
 	LivenessFailureThreshold  = 4
 	ReadinessFailureThreshold = 1
-
-	PodAffinityTermWeight = 100
 )
 
 //go:generate go run github.com/maxbrunsfeld/counterfeiter/v6 -generate

diff --git a/statefulset-runner/controllers/appworkload_to_stset.go b/statefulset-runner/controllers/appworkload_to_stset.go
@@ -4,7 +4,6 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"fmt"
-	"maps"
 	"regexp"
 	"slices"
 	"sort"
@@ -164,18 +163,23 @@ func (r *AppWorkloadToStatefulsetConverter) Convert(appWorkload *korifiv1alpha1.
 	statefulSet.Spec.Template.Spec.AutomountServiceAccountToken = tools.PtrTo(false)
 	statefulSet.Spec.Selector = statefulSetLabelSelector(appWorkload)
 
-	statefulSet.Spec.Template.Spec.Affinity = &corev1.Affinity{
-		PodAntiAffinity: &corev1.PodAntiAffinity{
-			PreferredDuringSchedulingIgnoredDuringExecution: []corev1.WeightedPodAffinityTerm{
-				{
-					Weight: PodAffinityTermWeight,
-					PodAffinityTerm: corev1.PodAffinityTerm{
-						TopologyKey: corev1.LabelHostname,
-						LabelSelector: &metav1.LabelSelector{
-							MatchExpressions: toLabelSelectorRequirements(statefulSet.Spec.Selector),
-						},
-					},
-				},
+	statefulSet.Spec.Template.Spec.TopologySpreadConstraints = []corev1.TopologySpreadConstraint{
+		{
+			TopologyKey:       "topology.kubernetes.io/zone",
+			MaxSkew:           1,
+			WhenUnsatisfiable: "ScheduleAnyway",
+			LabelSelector:     statefulSet.Spec.Selector,
+			MatchLabelKeys: []string{
+				"pod-template-hash",
+			},
+		},
+		{
+			TopologyKey:       "kubernetes.io/hostname",
+			MaxSkew:           1,
+			WhenUnsatisfiable: "ScheduleAnyway",
+			LabelSelector:     statefulSet.Spec.Selector,
+			MatchLabelKeys: []string{
+				"pod-template-hash",
 			},
 		},
 	}
@@ -232,18 +236,6 @@ func truncateString(str string, num int) string {
 	return str
 }
 
-func toLabelSelectorRequirements(selector *metav1.LabelSelector) []metav1.LabelSelectorRequirement {
-	labels := slices.Values(slices.Sorted(maps.Keys(selector.MatchLabels)))
-
-	return slices.Collect(it.Map(labels, func(label string) metav1.LabelSelectorRequirement {
-		return metav1.LabelSelectorRequirement{
-			Key:      label,
-			Operator: metav1.LabelSelectorOpIn,
-			Values:   []string{selector.MatchLabels[label]},
-		}
-	}))
-}
-
 func statefulSetLabelSelector(appWorkload *korifiv1alpha1.AppWorkload) *metav1.LabelSelector {
 	return &metav1.LabelSelector{
 		MatchLabels: map[string]string{

diff --git a/statefulset-runner/controllers/appworkload_to_stset_test.go b/statefulset-runner/controllers/appworkload_to_stset_test.go
@@ -270,21 +270,20 @@ var _ = Describe("AppWorkload to StatefulSet Converter", func() {
 		Expect(*statefulSet.Spec.Template.Spec.SecurityContext.RunAsNonRoot).To(BeTrue())
 	})
 
-	It("should set soft inter-pod anti-affinity", func() {
-		podAntiAffinity := statefulSet.Spec.Template.Spec.Affinity.PodAntiAffinity
-		Expect(podAntiAffinity.RequiredDuringSchedulingIgnoredDuringExecution).To(BeEmpty())
-		Expect(podAntiAffinity.PreferredDuringSchedulingIgnoredDuringExecution).To(HaveLen(1))
-
-		weightedTerm := podAntiAffinity.PreferredDuringSchedulingIgnoredDuringExecution[0]
-		Expect(weightedTerm.Weight).To(Equal(int32(100)))
-		Expect(weightedTerm.PodAffinityTerm.TopologyKey).To(Equal("kubernetes.io/hostname"))
-		Expect(weightedTerm.PodAffinityTerm.LabelSelector.MatchExpressions).To(ConsistOf(
-			metav1.LabelSelectorRequirement{
-				Key:      controllers.LabelGUID,
-				Operator: metav1.LabelSelectorOpIn,
-				Values:   []string{"guid_1234"},
-			},
-		))
+	It("should set topology spread constraint", func() {
+		topologySpreadConstraints := statefulSet.Spec.Template.Spec.TopologySpreadConstraints
+		Expect(topologySpreadConstraints).To(HaveLen(2))
+		keys := []string{}
+
+		for _, constraint := range topologySpreadConstraints {
+			keys = append(keys, constraint.TopologyKey)
+			Expect(constraint.MaxSkew).To(BeEquivalentTo(1))
+			Expect(constraint.WhenUnsatisfiable).To(BeEquivalentTo("ScheduleAnyway"))
+			Expect(constraint.LabelSelector).To(Equal(statefulSet.Spec.Selector))
+			Expect(constraint.MatchLabelKeys).To(ConsistOf("pod-template-hash"))
+		}
+
+		Expect(keys).To(ConsistOf("topology.kubernetes.io/zone", "kubernetes.io/hostname"))
 	})
 
 	It("should set the container environment variables", func() {