Merge pull request #113375 from atiratree/PodHealthyPolicy-api

api: add unhealthyPodEvictionPolicy for PDBs

pkg/apis/policy/types.go

@@ -42,8 +42,56 @@ type PodDisruptionBudgetSpec struct {
 	// by specifying 0. This is a mutually exclusive setting with "minAvailable".
 	// +optional
 	MaxUnavailable *intstr.IntOrString
+
+	// UnhealthyPodEvictionPolicy defines the criteria for when unhealthy pods
+	// should be considered for eviction. Current implementation considers healthy pods,
+	// as pods that have status.conditions item with type="Ready",status="True".
+	//
+	// Valid policies are IfHealthyBudget and AlwaysAllow.
+	// If no policy is specified, the default behavior will be used,
+	// which corresponds to the IfHealthyBudget policy.
+	//
+	// IfHealthyBudget policy means that running pods (status.phase="Running"),
+	// but not yet healthy can be evicted only if the guarded application is not
+	// disrupted (status.currentHealthy is at least equal to status.desiredHealthy).
+	// Healthy pods will be subject to the PDB for eviction.
+	//
+	// AlwaysAllow policy means that all running pods (status.phase="Running"),
+	// but not yet healthy are considered disrupted and can be evicted regardless
+	// of whether the criteria in a PDB is met. This means perspective running
+	// pods of a disrupted application might not get a chance to become healthy.
+	// Healthy pods will be subject to the PDB for eviction.
+	//
+	// Additional policies may be added in the future.
+	// Clients making eviction decisions should disallow eviction of unhealthy pods
+	// if they encounter an unrecognized policy in this field.
+	//
+	// This field is alpha-level. The eviction API uses this field when
+	// the feature gate PDBUnhealthyPodEvictionPolicy is enabled (disabled by default).
+	// +optional
+	UnhealthyPodEvictionPolicy *UnhealthyPodEvictionPolicyType
 }
 
+// UnhealthyPodEvictionPolicyType defines the criteria for when unhealthy pods
+// should be considered for eviction.
+// +enum
+type UnhealthyPodEvictionPolicyType string
+
+const (
+	// IfHealthyBudget policy means that running pods (status.phase="Running"),
+	// but not yet healthy can be evicted only if the guarded application is not
+	// disrupted (status.currentHealthy is at least equal to status.desiredHealthy).
+	// Healthy pods will be subject to the PDB for eviction.
+	IfHealthyBudget UnhealthyPodEvictionPolicyType = "IfHealthyBudget"
+
+	// AlwaysAllow policy means that all running pods (status.phase="Running"),
+	// but not yet healthy are considered disrupted and can be evicted regardless
+	// of whether the criteria in a PDB is met. This means perspective running
+	// pods of a disrupted application might not get a chance to become healthy.
+	// Healthy pods will be subject to the PDB for eviction.
+	AlwaysAllow UnhealthyPodEvictionPolicyType = "AlwaysAllow"
+)
+
 // PodDisruptionBudgetStatus represents information about the status of a
 // PodDisruptionBudget. Status may trail the actual state of a system.
 type PodDisruptionBudgetStatus struct {

pkg/apis/policy/v1/zz_generated.conversion.go

@@ -187,6 +187,7 @@ func autoConvert_v1_PodDisruptionBudgetSpec_To_policy_PodDisruptionBudgetSpec(in
 	out.MinAvailable = (*intstr.IntOrString)(unsafe.Pointer(in.MinAvailable))
 	out.Selector = (*metav1.LabelSelector)(unsafe.Pointer(in.Selector))
 	out.MaxUnavailable = (*intstr.IntOrString)(unsafe.Pointer(in.MaxUnavailable))
+	out.UnhealthyPodEvictionPolicy = (*policy.UnhealthyPodEvictionPolicyType)(unsafe.Pointer(in.UnhealthyPodEvictionPolicy))
 	return nil
 }
 
@@ -199,6 +200,7 @@ func autoConvert_policy_PodDisruptionBudgetSpec_To_v1_PodDisruptionBudgetSpec(in
 	out.MinAvailable = (*intstr.IntOrString)(unsafe.Pointer(in.MinAvailable))
 	out.Selector = (*metav1.LabelSelector)(unsafe.Pointer(in.Selector))
 	out.MaxUnavailable = (*intstr.IntOrString)(unsafe.Pointer(in.MaxUnavailable))
+	out.UnhealthyPodEvictionPolicy = (*v1.UnhealthyPodEvictionPolicyType)(unsafe.Pointer(in.UnhealthyPodEvictionPolicy))
 	return nil
 }
 

pkg/apis/policy/v1beta1/zz_generated.conversion.go

@@ -452,6 +452,7 @@ func autoConvert_v1beta1_PodDisruptionBudgetSpec_To_policy_PodDisruptionBudgetSp
 	out.MinAvailable = (*intstr.IntOrString)(unsafe.Pointer(in.MinAvailable))
 	out.Selector = (*v1.LabelSelector)(unsafe.Pointer(in.Selector))
 	out.MaxUnavailable = (*intstr.IntOrString)(unsafe.Pointer(in.MaxUnavailable))
+	out.UnhealthyPodEvictionPolicy = (*policy.UnhealthyPodEvictionPolicyType)(unsafe.Pointer(in.UnhealthyPodEvictionPolicy))
 	return nil
 }
 
@@ -464,6 +465,7 @@ func autoConvert_policy_PodDisruptionBudgetSpec_To_v1beta1_PodDisruptionBudgetSp
 	out.MinAvailable = (*intstr.IntOrString)(unsafe.Pointer(in.MinAvailable))
 	out.Selector = (*v1.LabelSelector)(unsafe.Pointer(in.Selector))
 	out.MaxUnavailable = (*intstr.IntOrString)(unsafe.Pointer(in.MaxUnavailable))
+	out.UnhealthyPodEvictionPolicy = (*v1beta1.UnhealthyPodEvictionPolicyType)(unsafe.Pointer(in.UnhealthyPodEvictionPolicy))
 	return nil
 }
 

pkg/apis/policy/validation/validation.go

@@ -44,6 +44,11 @@ const (
 	seccompAllowedProfilesAnnotationKey = "seccomp.security.alpha.kubernetes.io/allowedProfileNames"
 )
 
+var supportedUnhealthyPodEvictionPolicies = sets.NewString(
+	string(policy.IfHealthyBudget),
+	string(policy.AlwaysAllow),
+)
+
 type PodDisruptionBudgetValidationOptions struct {
 	AllowInvalidLabelValueInSelector bool
 }
@@ -78,6 +83,10 @@ func ValidatePodDisruptionBudgetSpec(spec policy.PodDisruptionBudgetSpec, opts P
 
 	allErrs = append(allErrs, unversionedvalidation.ValidateLabelSelector(spec.Selector, labelSelectorValidationOptions, fldPath.Child("selector"))...)
 
+	if spec.UnhealthyPodEvictionPolicy != nil && !supportedUnhealthyPodEvictionPolicies.Has(string(*spec.UnhealthyPodEvictionPolicy)) {
+		allErrs = append(allErrs, field.NotSupported(fldPath.Child("unhealthyPodEvictionPolicy"), *spec.UnhealthyPodEvictionPolicy, supportedUnhealthyPodEvictionPolicies.List()))
+	}
+
 	return allErrs
 }
 

pkg/apis/policy/validation/validation_test.go

@@ -98,6 +98,63 @@ func TestValidateMinAvailablePodAndMaxUnavailableDisruptionBudgetSpec(t *testing
 	}
 }
 
+func TestValidateUnhealthyPodEvictionPolicyDisruptionBudgetSpec(t *testing.T) {
+	c1 := intstr.FromString("10%")
+	alwaysAllowPolicy := policy.AlwaysAllow
+	invalidPolicy := policy.UnhealthyPodEvictionPolicyType("Invalid")
+
+	testCases := []struct {
+		name      string
+		pdbSpec   policy.PodDisruptionBudgetSpec
+		expectErr bool
+	}{
+		{
+			name: "valid nil UnhealthyPodEvictionPolicy",
+			pdbSpec: policy.PodDisruptionBudgetSpec{
+				MinAvailable:               &c1,
+				UnhealthyPodEvictionPolicy: nil,
+			},
+			expectErr: false,
+		},
+		{
+			name: "valid UnhealthyPodEvictionPolicy",
+			pdbSpec: policy.PodDisruptionBudgetSpec{
+				MinAvailable:               &c1,
+				UnhealthyPodEvictionPolicy: &alwaysAllowPolicy,
+			},
+			expectErr: false,
+		},
+		{
+			name: "empty UnhealthyPodEvictionPolicy",
+			pdbSpec: policy.PodDisruptionBudgetSpec{
+				MinAvailable:               &c1,
+				UnhealthyPodEvictionPolicy: new(policy.UnhealthyPodEvictionPolicyType),
+			},
+			expectErr: true,
+		},
+		{
+			name: "invalid UnhealthyPodEvictionPolicy",
+			pdbSpec: policy.PodDisruptionBudgetSpec{
+				MinAvailable:               &c1,
+				UnhealthyPodEvictionPolicy: &invalidPolicy,
+			},
+			expectErr: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			errs := ValidatePodDisruptionBudgetSpec(tc.pdbSpec, PodDisruptionBudgetValidationOptions{true}, field.NewPath("foo"))
+			if len(errs) == 0 && tc.expectErr {
+				t.Errorf("unexpected success for %v", tc.pdbSpec)
+			}
+			if len(errs) != 0 && !tc.expectErr {
+				t.Errorf("unexpected failure for %v", tc.pdbSpec)
+			}
+		})
+	}
+}
+
 func TestValidatePodDisruptionBudgetStatus(t *testing.T) {
 	const expectNoErrors = false
 	const expectErrors = true

pkg/apis/policy/zz_generated.deepcopy.go

@@ -239,6 +239,11 @@ func (in *PodDisruptionBudgetSpec) DeepCopyInto(out *PodDisruptionBudgetSpec) {
 		*out = new(intstr.IntOrString)
 		**out = **in
 	}
+	if in.UnhealthyPodEvictionPolicy != nil {
+		in, out := &in.UnhealthyPodEvictionPolicy, &out.UnhealthyPodEvictionPolicy
+		*out = new(UnhealthyPodEvictionPolicyType)
+		**out = **in
+	}
 	return
 }