From a523a0254da9f728866cb8211a8af0929ab69fff Mon Sep 17 00:00:00 2001
From: Andrei Kvapil <kvapss@gmail.com>
Date: Mon, 22 Jul 2024 23:46:47 +0200
Subject: [PATCH] update webhook to reject decreasing storage size

Signed-off-by: Andrei Kvapil <kvapss@gmail.com>
---
 api/v1alpha1/etcdcluster_webhook.go      | 18 +++++++++++
 api/v1alpha1/etcdcluster_webhook_test.go | 40 ++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/api/v1alpha1/etcdcluster_webhook.go b/api/v1alpha1/etcdcluster_webhook.go
index 18c7971..941a737 100644
--- a/api/v1alpha1/etcdcluster_webhook.go
+++ b/api/v1alpha1/etcdcluster_webhook.go
@@ -107,11 +107,26 @@ func (r *EtcdCluster) ValidateUpdate(old runtime.Object) (admission.Warnings, er
 	etcdclusterlog.Info("validate update", "name", r.Name)
 	var warnings admission.Warnings
 	oldCluster := old.(*EtcdCluster)
+
+	// Check if replicas are being resized
 	if *oldCluster.Spec.Replicas != *r.Spec.Replicas {
 		warnings = append(warnings, "cluster resize is not currently supported")
 	}
 
 	var allErrors field.ErrorList
+
+	// Check if storage size is being decreased
+	oldStorage := oldCluster.Spec.Storage.VolumeClaimTemplate.Spec.Resources.Requests[corev1.ResourceStorage]
+	newStorage := r.Spec.Storage.VolumeClaimTemplate.Spec.Resources.Requests[corev1.ResourceStorage]
+	if newStorage.Cmp(oldStorage) < 0 {
+		allErrors = append(allErrors, field.Invalid(
+			field.NewPath("spec", "storage", "volumeClaimTemplate", "resources", "requests", "storage"),
+			newStorage.String(),
+			"decreasing storage size is not allowed"),
+		)
+	}
+
+	// Check if storage type is changing
 	if oldCluster.Spec.Storage.EmptyDir == nil && r.Spec.Storage.EmptyDir != nil ||
 		oldCluster.Spec.Storage.EmptyDir != nil && r.Spec.Storage.EmptyDir == nil {
 		allErrors = append(allErrors, field.Invalid(
@@ -121,6 +136,7 @@ func (r *EtcdCluster) ValidateUpdate(old runtime.Object) (admission.Warnings, er
 		)
 	}
 
+	// Validate PodDisruptionBudget
 	pdbWarnings, pdbErr := r.validatePdb()
 	if pdbErr != nil {
 		allErrors = append(allErrors, pdbErr...)
@@ -129,11 +145,13 @@ func (r *EtcdCluster) ValidateUpdate(old runtime.Object) (admission.Warnings, er
 		warnings = append(warnings, pdbWarnings...)
 	}
 
+	// Validate Security
 	securityErr := r.validateSecurity()
 	if securityErr != nil {
 		allErrors = append(allErrors, securityErr...)
 	}
 
+	// Validate Options
 	if errOptions := validateOptions(r); errOptions != nil {
 		allErrors = append(allErrors, field.Invalid(
 			field.NewPath("spec", "options"),
diff --git a/api/v1alpha1/etcdcluster_webhook_test.go b/api/v1alpha1/etcdcluster_webhook_test.go
index 23fe9c7..fa72ee7 100644
--- a/api/v1alpha1/etcdcluster_webhook_test.go
+++ b/api/v1alpha1/etcdcluster_webhook_test.go
@@ -111,6 +111,46 @@ var _ = Describe("EtcdCluster Webhook", func() {
 			}
 		})
 
+		It("Should reject decreasing storage size", func() {
+			etcdCluster := &EtcdCluster{
+				Spec: EtcdClusterSpec{
+					Replicas: ptr.To(int32(1)),
+					Storage: StorageSpec{
+						VolumeClaimTemplate: EmbeddedPersistentVolumeClaim{
+							Spec: corev1.PersistentVolumeClaimSpec{
+								Resources: corev1.VolumeResourceRequirements{
+									Requests: map[corev1.ResourceName]resource.Quantity{
+										corev1.ResourceStorage: resource.MustParse("5Gi"),
+									},
+								},
+							},
+						},
+					},
+				},
+			}
+			oldCluster := &EtcdCluster{
+				Spec: EtcdClusterSpec{
+					Replicas: ptr.To(int32(1)),
+					Storage: StorageSpec{
+						VolumeClaimTemplate: EmbeddedPersistentVolumeClaim{
+							Spec: corev1.PersistentVolumeClaimSpec{
+								Resources: corev1.VolumeResourceRequirements{
+									Requests: map[corev1.ResourceName]resource.Quantity{
+										corev1.ResourceStorage: resource.MustParse("10Gi"),
+									},
+								},
+							},
+						},
+					},
+				},
+			}
+			_, err := etcdCluster.ValidateUpdate(oldCluster)
+			if Expect(err).To(HaveOccurred()) {
+				statusErr := err.(*errors.StatusError)
+				Expect(statusErr.ErrStatus.Message).To(ContainSubstring("decreasing storage size is not allowed"))
+			}
+		})
+
 		It("Should allow changing emptydir size", func() {
 			etcdCluster := &EtcdCluster{
 				Spec: EtcdClusterSpec{