topologyspreadconstraint: support matchLabelKeys

Signed-off-by: Amir Alavi <amiralavi7@gmail.com>

hack/kind_config.yaml

@@ -1,5 +1,9 @@
 kind: Cluster
 apiVersion: kind.x-k8s.io/v1alpha4
+featureGates:
+  # beta as of 1.27 but we currently run e2e on 1.26
+  # this flag should be removed as part of Descheduler 0.29 release
+  MatchLabelKeysInPodTopologySpread: true
 nodes:
 - role: control-plane
 - role: worker

pkg/framework/plugins/removepodsviolatingtopologyspreadconstraint/topologyspreadconstraint.go

@@ -147,12 +147,9 @@ func (d *RemovePodsViolatingTopologySpreadConstraint) Balance(ctx context.Contex
 				if !allowedConstraints.Has(constraint.WhenUnsatisfiable) {
 					continue
 				}
-				requiredSchedulingTerm := nodeaffinity.GetRequiredNodeAffinity(pod)
-				namespaceTopologySpreadConstraint := topologyConstraintSet{
-					constraint:      constraint,
-					podNodeAffinity: requiredSchedulingTerm,
-					podTolerations:  pod.Spec.Tolerations,
-				}
+
+				namespaceTopologySpreadConstraint := newTopologyConstraintSet(constraint, pod)
+
 				// Need to check v1.TopologySpreadConstraint deepEquality because
 				// v1.TopologySpreadConstraint has pointer fields
 				// and we don't need to go over duplicated constraints later on
@@ -496,3 +493,22 @@ func matchNodeInclusionPolicies(tsc *v1.TopologySpreadConstraint, tolerations []
 	}
 	return true
 }
+
+func newTopologyConstraintSet(constraint v1.TopologySpreadConstraint, pod *v1.Pod) topologyConstraintSet {
+	if pod.Labels != nil && len(constraint.MatchLabelKeys) > 0 {
+		if constraint.LabelSelector == nil {
+			constraint.LabelSelector = &metav1.LabelSelector{}
+		}
+
+		for _, labelKey := range constraint.MatchLabelKeys {
+			metav1.AddLabelToSelector(constraint.LabelSelector, labelKey, pod.Labels[labelKey])
+		}
+	}
+
+	requiredSchedulingTerm := nodeaffinity.GetRequiredNodeAffinity(pod)
+	return topologyConstraintSet{
+		constraint:      constraint,
+		podNodeAffinity: requiredSchedulingTerm,
+		podTolerations:  pod.Spec.Tolerations,
+	}
+}

pkg/framework/plugins/removepodsviolatingtopologyspreadconstraint/topologyspreadconstraint_test.go

@@ -6,6 +6,7 @@ import (
 	"sort"
 	"testing"
 
+	appsv1 "k8s.io/api/apps/v1"
 	v1 "k8s.io/api/core/v1"
 	policy "k8s.io/api/policy/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -1064,6 +1065,55 @@ func TestTopologySpreadConstraint(t *testing.T) {
 			namespaces:           []string{"ns1"},
 			args:                 RemovePodsViolatingTopologySpreadConstraintArgs{LabelSelector: getLabelSelector("foo", []string{"baz"}, metav1.LabelSelectorOpNotIn)},
 		},
+		{
+			name: "2 domains, sizes [2,0], maxSkew=1, move 1 pods given matchLabelKeys on same replicaset",
+			nodes: []*v1.Node{
+				test.BuildTestNode("n1", 2000, 3000, 10, func(n *v1.Node) { n.Labels["zone"] = "zoneA" }),
+				test.BuildTestNode("n2", 2000, 3000, 10, func(n *v1.Node) { n.Labels["zone"] = "zoneB" }),
+			},
+			pods: createTestPods([]testPodList{
+				{
+					count:       1,
+					node:        "n1",
+					labels:      map[string]string{"foo": "bar", appsv1.DefaultDeploymentUniqueLabelKey: "foo"},
+					constraints: getDefaultTopologyConstraintsWithPodTemplateHashMatch(1),
+				},
+				{
+					count:       1,
+					node:        "n1",
+					labels:      map[string]string{"foo": "bar", appsv1.DefaultDeploymentUniqueLabelKey: "foo"},
+					constraints: getDefaultTopologyConstraintsWithPodTemplateHashMatch(1),
+				},
+			}),
+			expectedEvictedCount: 1,
+			expectedEvictedPods:  []string{"pod-1"},
+			namespaces:           []string{"ns1"},
+			args:                 RemovePodsViolatingTopologySpreadConstraintArgs{LabelSelector: getLabelSelector("foo", []string{"baz"}, metav1.LabelSelectorOpNotIn)},
+		},
+		{
+			name: "2 domains, sizes [2,0], maxSkew=1, move 0 pods given matchLabelKeys on two different replicasets",
+			nodes: []*v1.Node{
+				test.BuildTestNode("n1", 2000, 3000, 10, func(n *v1.Node) { n.Labels["zone"] = "zoneA" }),
+				test.BuildTestNode("n2", 2000, 3000, 10, func(n *v1.Node) { n.Labels["zone"] = "zoneB" }),
+			},
+			pods: createTestPods([]testPodList{
+				{
+					count:       1,
+					node:        "n1",
+					labels:      map[string]string{"foo": "bar", appsv1.DefaultDeploymentUniqueLabelKey: "foo"},
+					constraints: getDefaultTopologyConstraintsWithPodTemplateHashMatch(1),
+				},
+				{
+					count:       1,
+					node:        "n1",
+					labels:      map[string]string{"foo": "bar", appsv1.DefaultDeploymentUniqueLabelKey: "bar"},
+					constraints: getDefaultTopologyConstraintsWithPodTemplateHashMatch(1),
+				},
+			}),
+			expectedEvictedCount: 0,
+			namespaces:           []string{"ns1"},
+			args:                 RemovePodsViolatingTopologySpreadConstraintArgs{LabelSelector: getLabelSelector("foo", []string{"baz"}, metav1.LabelSelectorOpNotIn)},
+		},
 		{
 			name: "2 domains, sizes [4,2], maxSkew=1, 2 pods in termination; nothing should be moved",
 			nodes: []*v1.Node{
@@ -1543,6 +1593,18 @@ func getDefaultNodeTopologyConstraints(maxSkew int32) []v1.TopologySpreadConstra
 	}
 }
 
+func getDefaultTopologyConstraintsWithPodTemplateHashMatch(maxSkew int32) []v1.TopologySpreadConstraint {
+	return []v1.TopologySpreadConstraint{
+		{
+			MaxSkew:           maxSkew,
+			TopologyKey:       "zone",
+			WhenUnsatisfiable: v1.DoNotSchedule,
+			LabelSelector:     &metav1.LabelSelector{MatchLabels: map[string]string{"foo": "bar"}},
+			MatchLabelKeys:    []string{appsv1.DefaultDeploymentUniqueLabelKey},
+		},
+	}
+}
+
 func TestCheckIdenticalConstraints(t *testing.T) {
 	newConstraintSame := v1.TopologySpreadConstraint{
 		MaxSkew:           2,

test/e2e/e2e_topologyspreadconstraint_test.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 	"testing"
 
+	appsv1 "k8s.io/api/apps/v1"
 	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/labels"
@@ -34,11 +35,13 @@ func TestTopologySpreadConstraint(t *testing.T) {
 	defer clientSet.CoreV1().Namespaces().Delete(ctx, testNamespace.Name, metav1.DeleteOptions{})
 
 	testCases := map[string]struct {
+		expectedEvictedCount     uint
 		replicaCount             int
 		topologySpreadConstraint v1.TopologySpreadConstraint
 	}{
 		"test-rc-topology-spread-hard-constraint": {
-			replicaCount: 4,
+			expectedEvictedCount: 1,
+			replicaCount:         4,
 			topologySpreadConstraint: v1.TopologySpreadConstraint{
 				LabelSelector: &metav1.LabelSelector{
 					MatchLabels: map[string]string{
@@ -51,7 +54,8 @@ func TestTopologySpreadConstraint(t *testing.T) {
 			},
 		},
 		"test-rc-topology-spread-soft-constraint": {
-			replicaCount: 4,
+			expectedEvictedCount: 1,
+			replicaCount:         4,
 			topologySpreadConstraint: v1.TopologySpreadConstraint{
 				LabelSelector: &metav1.LabelSelector{
 					MatchLabels: map[string]string{
@@ -64,7 +68,8 @@ func TestTopologySpreadConstraint(t *testing.T) {
 			},
 		},
 		"test-rc-node-taints-policy-honor": {
-			replicaCount: 4,
+			expectedEvictedCount: 1,
+			replicaCount:         4,
 			topologySpreadConstraint: v1.TopologySpreadConstraint{
 				LabelSelector: &metav1.LabelSelector{
 					MatchLabels: map[string]string{
@@ -78,7 +83,8 @@ func TestTopologySpreadConstraint(t *testing.T) {
 			},
 		},
 		"test-rc-node-affinity-policy-ignore": {
-			replicaCount: 4,
+			expectedEvictedCount: 1,
+			replicaCount:         4,
 			topologySpreadConstraint: v1.TopologySpreadConstraint{
 				LabelSelector: &metav1.LabelSelector{
 					MatchLabels: map[string]string{
@@ -91,6 +97,21 @@ func TestTopologySpreadConstraint(t *testing.T) {
 				WhenUnsatisfiable:  v1.DoNotSchedule,
 			},
 		},
+		"test-rc-match-label-keys": {
+			expectedEvictedCount: 0,
+			replicaCount:         4,
+			topologySpreadConstraint: v1.TopologySpreadConstraint{
+				LabelSelector: &metav1.LabelSelector{
+					MatchLabels: map[string]string{
+						"test": "match-label-keys",
+					},
+				},
+				MatchLabelKeys:    []string{appsv1.DefaultDeploymentUniqueLabelKey},
+				MaxSkew:           1,
+				TopologyKey:       zoneTopologyKey,
+				WhenUnsatisfiable: v1.DoNotSchedule,
+			},
+		},
 	}
 	for name, tc := range testCases {
 		t.Run(name, func(t *testing.T) {
@@ -158,10 +179,14 @@ func TestTopologySpreadConstraint(t *testing.T) {
 			t.Logf("Wait for terminating pods of %s to disappear", name)
 			waitForTerminatingPodsToDisappear(ctx, t, clientSet, rc.Namespace)
 
-			if totalEvicted := podEvictor.TotalEvicted(); totalEvicted > 0 {
+			if totalEvicted := podEvictor.TotalEvicted(); totalEvicted == tc.expectedEvictedCount {
 				t.Logf("Total of %d Pods were evicted for %s", totalEvicted, name)
 			} else {
-				t.Fatalf("Pods were not evicted for %s TopologySpreadConstraint", name)
+				t.Fatalf("Expected %d evictions but got %d for %s TopologySpreadConstraint", tc.expectedEvictedCount, totalEvicted, name)
+			}
+
+			if tc.expectedEvictedCount == 0 {
+				return
 			}
 
 			// Ensure recently evicted Pod are rescheduled and running before asserting for a balanced topology spread