[release-2.11] 🐛 fix: Prevent volumeSize updates in ROSAMachinePool

config/crd/bases/infrastructure.cluster.x-k8s.io_rosamachinepools.yaml

@@ -233,6 +233,9 @@ spec:
                 maximum: 16384
                 minimum: 75
                 type: integer
+                x-kubernetes-validations:
+                - message: volumeSize is immutable
+                  rule: self == oldSelf
             required:
             - instanceType
             - nodePoolName

exp/api/v1beta2/rosamachinepool_types.go

@@ -103,6 +103,7 @@ type RosaMachinePoolSpec struct {
 	// VolumeSize set the disk volume size for the machine pool, in Gib. The default is 300 GiB.
 	// +kubebuilder:validation:Minimum=75
 	// +kubebuilder:validation:Maximum=16384
+	// +kubebuilder:validation:XValidation:rule="self == oldSelf", message="volumeSize is immutable"
 	// +immutable
 	// +optional
 	VolumeSize int `json:"volumeSize,omitempty"`

exp/controllers/rosamachinepool_controller.go

@@ -402,6 +402,7 @@ func (r *ROSAMachinePoolReconciler) updateNodePool(machinePoolScope *scope.RosaM
 	desiredSpec.Version = ""
 	desiredSpec.AdditionalSecurityGroups = nil
 	desiredSpec.AdditionalTags = nil
+	desiredSpec.VolumeSize = 0
 
 	npBuilder := nodePoolBuilder(desiredSpec, machinePoolScope.MachinePool.Spec, machinePoolScope.ControlPlane.Spec.ChannelGroup, machinePoolScope.ControlPlane.Spec.Channel)
 	nodePoolSpec, err := npBuilder.Build()
@@ -430,6 +431,7 @@ func computeSpecDiff(desiredSpec expinfrav1.RosaMachinePoolSpec, nodePool *cmv1.
 		"Version",                  // Version changes are reconciled separately.
 		"AdditionalTags",           // AdditionalTags day2 changes not supported.
 		"AdditionalSecurityGroups", // AdditionalSecurityGroups day2 changes not supported.
+		"VolumeSize",               // VolumeSize is immutable after creation.
 	}
 
 	return cmp.Diff(desiredSpec, currentSpec,

exp/controllers/rosamachinepool_controller_test.go

@@ -708,6 +708,54 @@ func TestRosaMachinePoolReconcile(t *testing.T) {
 	})
 }
 
+func TestVolumeSizeIgnoredInDiff(t *testing.T) {
+	g := NewWithT(t)
+
+	rosaMachinePoolSpec := expinfrav1.RosaMachinePoolSpec{
+		NodePoolName: "test-nodepool",
+		Version:      "4.14.5",
+		Subnet:       "subnet-id",
+		AutoRepair:   true,
+		InstanceType: "m5.large",
+		VolumeSize:   300,
+	}
+
+	// Create a NodePool with different volumeSize
+	nodePool, err := cmv1.NewNodePool().
+		ID("test-nodepool").
+		Version(cmv1.NewVersion().ID("openshift-v4.14.5")).
+		Subnet("subnet-id").
+		AutoRepair(true).
+		AWSNodePool(cmv1.NewAWSNodePool().
+			InstanceType("m5.large").
+			RootVolume(cmv1.NewAWSVolume().Size(400))).
+		Build()
+	g.Expect(err).ToNot(HaveOccurred())
+
+	diff := computeSpecDiff(rosaMachinePoolSpec, nodePool)
+	g.Expect(diff).To(BeEmpty(), "volumeSize should be ignored in diff computation")
+}
+
+func TestVolumeSizeZeroedBeforeUpdate(t *testing.T) {
+	g := NewWithT(t)
+
+	desiredSpec := expinfrav1.RosaMachinePoolSpec{
+		NodePoolName: "test-nodepool",
+		InstanceType: "m5.large",
+		VolumeSize:   0,
+	}
+
+	machinePoolSpec := clusterv1.MachinePoolSpec{
+		Replicas: ptr.To[int32](2),
+	}
+	nodePoolBuilder := nodePoolBuilder(desiredSpec, machinePoolSpec, rosacontrolplanev1.Stable, "")
+	nodePoolSpec, err := nodePoolBuilder.Build()
+	g.Expect(err).ToNot(HaveOccurred())
+
+	g.Expect(nodePoolSpec.AWSNodePool()).ToNot(BeNil())
+	g.Expect(nodePoolSpec.AWSNodePool().RootVolume()).To(BeNil(), "RootVolume should not be set when volumeSize is 0")
+}
+
 func createObject(g *WithT, obj client.Object, namespace string) {
 	if obj.DeepCopyObject() != nil {
 		obj.SetNamespace(namespace)