api defination for MatchLabelKeys in TopologySpreadConstraint

Signed-off-by: Alex Wang <wangqingcan1990@gmail.com>

pkg/api/pod/util.go

@@ -553,6 +553,7 @@ func dropDisabledFields(
 
 	dropDisabledTopologySpreadConstraintsFields(podSpec, oldPodSpec)
 	dropDisabledNodeInclusionPolicyFields(podSpec, oldPodSpec)
+	dropDisabledMatchLabelKeysField(podSpec, oldPodSpec)
 }
 
 // dropDisabledTopologySpreadConstraintsFields removes disabled fields from PodSpec related
@@ -626,6 +627,31 @@ func dropDisabledNodeInclusionPolicyFields(podSpec, oldPodSpec *api.PodSpec) {
 	}
 }
 
+// dropDisabledMatchLabelKeysField removes disabled fields from PodSpec related
+// to MatchLabelKeys only if it is not already used by the old spec.
+func dropDisabledMatchLabelKeysField(podSpec, oldPodSpec *api.PodSpec) {
+	if !utilfeature.DefaultFeatureGate.Enabled(features.MatchLabelKeysInPodTopologySpread) && !matchLabelKeysInUse(oldPodSpec) {
+		for i := range podSpec.TopologySpreadConstraints {
+			podSpec.TopologySpreadConstraints[i].MatchLabelKeys = nil
+		}
+	}
+}
+
+// matchLabelKeysInUse returns true if the pod spec is non-nil
+// and has MatchLabelKeys field set in TopologySpreadConstraints.
+func matchLabelKeysInUse(podSpec *api.PodSpec) bool {
+	if podSpec == nil {
+		return false
+	}
+
+	for _, c := range podSpec.TopologySpreadConstraints {
+		if len(c.MatchLabelKeys) > 0 {
+			return true
+		}
+	}
+	return false
+}
+
 // nodeAffinityPolicyInUse returns true if the pod spec is non-nil and has NodeAffinityPolicy field set
 // in TopologySpreadConstraints
 func nodeAffinityPolicyInUse(podSpec *api.PodSpec) bool {

pkg/api/pod/util_test.go

@@ -1930,3 +1930,138 @@ func TestDropNodeInclusionPolicyFields(t *testing.T) {
 		})
 	}
 }
+
+func TestDropDisabledMatchLabelKeysField(t *testing.T) {
+	tests := []struct {
+		name        string
+		enabled     bool
+		podSpec     *api.PodSpec
+		oldPodSpec  *api.PodSpec
+		wantPodSpec *api.PodSpec
+	}{
+		{
+			name:    "feature disabled, both pods don't use MatchLabelKeys fields",
+			enabled: false,
+			oldPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{},
+			},
+			podSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{},
+			},
+			wantPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{},
+			},
+		},
+		{
+			name:    "feature disabled, only old pod uses MatchLabelKeys field",
+			enabled: false,
+			oldPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{
+					{MatchLabelKeys: []string{"foo"}},
+				},
+			},
+			podSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{},
+			},
+			wantPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{},
+			},
+		},
+		{
+			name:    "feature disabled, only current pod uses MatchLabelKeys field",
+			enabled: false,
+			oldPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{},
+			},
+			podSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{
+					{MatchLabelKeys: []string{"foo"}},
+				},
+			},
+			wantPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{{}},
+			},
+		},
+		{
+			name:    "feature disabled, both pods use MatchLabelKeys fields",
+			enabled: false,
+			oldPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{
+					{MatchLabelKeys: []string{"foo"}},
+				},
+			},
+			podSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{
+					{MatchLabelKeys: []string{"foo"}},
+				},
+			},
+			wantPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{
+					{MatchLabelKeys: []string{"foo"}},
+				},
+			},
+		},
+		{
+			name:    "feature enabled, only old pod uses MatchLabelKeys field",
+			enabled: true,
+			oldPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{
+					{MatchLabelKeys: []string{"foo"}},
+				},
+			},
+			podSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{},
+			},
+			wantPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{},
+			},
+		},
+		{
+			name:    "feature enabled, only current pod uses MatchLabelKeys field",
+			enabled: true,
+			oldPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{},
+			},
+			podSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{
+					{MatchLabelKeys: []string{"foo"}},
+				},
+			},
+			wantPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{
+					{MatchLabelKeys: []string{"foo"}},
+				},
+			},
+		},
+		{
+			name:    "feature enabled, both pods use MatchLabelKeys fields",
+			enabled: false,
+			oldPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{
+					{MatchLabelKeys: []string{"foo"}},
+				},
+			},
+			podSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{
+					{MatchLabelKeys: []string{"foo"}},
+				},
+			},
+			wantPodSpec: &api.PodSpec{
+				TopologySpreadConstraints: []api.TopologySpreadConstraint{
+					{MatchLabelKeys: []string{"foo"}},
+				},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.MatchLabelKeysInPodTopologySpread, test.enabled)()
+
+			dropDisabledFields(test.podSpec, nil, test.oldPodSpec, nil)
+			if diff := cmp.Diff(test.wantPodSpec, test.podSpec); diff != "" {
+				t.Errorf("unexpected pod spec (-want, +got):\n%s", diff)
+			}
+		})
+	}
+}

pkg/apis/core/types.go

@@ -5732,6 +5732,15 @@ type TopologySpreadConstraint struct {
 	// This is a alpha-level feature enabled by the NodeInclusionPolicyInPodTopologySpread feature flag.
 	// +optional
 	NodeTaintsPolicy *NodeInclusionPolicy
+	// MatchLabelKeys is a set of pod label keys to select the pods over which
+	// spreading will be calculated. The keys are used to lookup values from the
+	// incoming pod labels, those key-value labels are ANDed with labelSelector
+	// to select the group of existing pods over which spreading will be calculated
+	// for the incoming pod. Keys that don't exist in the incoming pod labels will
+	// be ignored. A null or empty list means only match against labelSelector.
+	// +listType=atomic
+	// +optional
+	MatchLabelKeys []string
 }
 
 // These are the built-in errors for PortStatus.

pkg/apis/core/validation/validation.go

@@ -6490,6 +6490,7 @@ func validateTopologySpreadConstraints(constraints []core.TopologySpreadConstrai
 		if err := validateNodeInclusionPolicy(subFldPath.Child("nodeTaintsPolicy"), constraint.NodeTaintsPolicy); err != nil {
 			allErrs = append(allErrs, err)
 		}
+		allErrs = append(allErrs, validateMatchLabelKeys(subFldPath.Child("matchLabelKeys"), constraint.MatchLabelKeys, constraint.LabelSelector)...)
 	}
 
 	return allErrs
@@ -6563,6 +6564,33 @@ func validateNodeInclusionPolicy(fldPath *field.Path, policy *core.NodeInclusion
 	return nil
 }
 
+// validateMatchLabelKeys tests that the elements are a valid label name and are not already included in labelSelector.
+func validateMatchLabelKeys(fldPath *field.Path, matchLabelKeys []string, labelSelector *metav1.LabelSelector) field.ErrorList {
+	if len(matchLabelKeys) == 0 {
+		return nil
+	}
+
+	labelSelectorKeys := sets.String{}
+	if labelSelector != nil {
+		for key := range labelSelector.MatchLabels {
+			labelSelectorKeys.Insert(key)
+		}
+		for _, matchExpression := range labelSelector.MatchExpressions {
+			labelSelectorKeys.Insert(matchExpression.Key)
+		}
+	}
+
+	allErrs := field.ErrorList{}
+	for i, key := range matchLabelKeys {
+		allErrs = append(allErrs, unversionedvalidation.ValidateLabelName(key, fldPath.Index(i))...)
+		if labelSelectorKeys.Has(key) {
+			allErrs = append(allErrs, field.Invalid(fldPath.Index(i), key, "exists in both matchLabelKeys and labelSelector"))
+		}
+	}
+
+	return allErrs
+}
+
 // ValidateServiceClusterIPsRelatedFields validates .spec.ClusterIPs,,
 // .spec.IPFamilies, .spec.ipFamilyPolicy.  This is exported because it is used
 // during IP init and allocation.

pkg/apis/core/validation/validation_test.go

@@ -18855,6 +18855,7 @@ func TestValidateTopologySpreadConstraints(t *testing.T) {
 	fieldPathTopologyKey := subFldPath0.Child("topologyKey")
 	fieldPathWhenUnsatisfiable := subFldPath0.Child("whenUnsatisfiable")
 	fieldPathTopologyKeyAndWhenUnsatisfiable := subFldPath0.Child("{topologyKey, whenUnsatisfiable}")
+	fieldPathMatchLabelKeys := subFldPath0.Child("matchLabelKeys")
 	nodeAffinityField := subFldPath0.Child("nodeAffinityPolicy")
 	nodeTaintsField := subFldPath0.Child("nodeTaintsPolicy")
 	unknown := core.NodeInclusionPolicy("Unknown")
@@ -19033,6 +19034,39 @@ func TestValidateTopologySpreadConstraints(t *testing.T) {
 				field.NotSupported(nodeTaintsField, &unknown, supportedPodTopologySpreadNodePolicies.List()),
 			},
 		},
+		{
+			name: "key in MatchLabelKeys isn't correctly defined",
+			constraints: []core.TopologySpreadConstraint{
+				{
+					MaxSkew:           1,
+					TopologyKey:       "k8s.io/zone",
+					WhenUnsatisfiable: core.DoNotSchedule,
+					MatchLabelKeys:    []string{"/simple"},
+				},
+			},
+			wantFieldErrors: []*field.Error{field.Invalid(fieldPathMatchLabelKeys.Index(0), "/simple", "prefix part must be non-empty")},
+		},
+		{
+			name: "key exists in both matchLabelKeys and labelSelector",
+			constraints: []core.TopologySpreadConstraint{
+				{
+					MaxSkew:           1,
+					TopologyKey:       "k8s.io/zone",
+					WhenUnsatisfiable: core.DoNotSchedule,
+					MatchLabelKeys:    []string{"foo"},
+					LabelSelector: &metav1.LabelSelector{
+						MatchExpressions: []metav1.LabelSelectorRequirement{
+							{
+								Key:      "foo",
+								Operator: metav1.LabelSelectorOpNotIn,
+								Values:   []string{"value1", "value2"},
+							},
+						},
+					},
+				},
+			},
+			wantFieldErrors: []*field.Error{field.Invalid(fieldPathMatchLabelKeys.Index(0), "foo", "exists in both matchLabelKeys and labelSelector")},
+		},
 	}
 
 	for _, tc := range testCases {

staging/src/k8s.io/api/core/v1/types.go

@@ -3455,6 +3455,15 @@ type TopologySpreadConstraint struct {
 	// This is a alpha-level feature enabled by the NodeInclusionPolicyInPodTopologySpread feature flag.
 	// +optional
 	NodeTaintsPolicy *NodeInclusionPolicy `json:"nodeTaintsPolicy,omitempty" protobuf:"bytes,7,opt,name=nodeTaintsPolicy"`
+	// MatchLabelKeys is a set of pod label keys to select the pods over which
+	// spreading will be calculated. The keys are used to lookup values from the
+	// incoming pod labels, those key-value labels are ANDed with labelSelector
+	// to select the group of existing pods over which spreading will be calculated
+	// for the incoming pod. Keys that don't exist in the incoming pod labels will
+	// be ignored. A null or empty list means only match against labelSelector.
+	// +listType=atomic
+	// +optional
+	MatchLabelKeys []string `json:"matchLabelKeys,omitempty" protobuf:"bytes,8,opt,name=matchLabelKeys"`
 }
 
 const (