From a82e4e8f5d47e487c20f65db1e79db32cb8f40cf Mon Sep 17 00:00:00 2001
From: mihaiandreiratoiu <mihai.ratoiu@uipath.com>
Date: Thu, 23 Nov 2023 13:51:23 +0200
Subject: [PATCH] Fix: DNSPrefix error on existing cluster

---
 api/v1beta1/azuremanagedcontrolplane_default.go |  3 ++-
 api/v1beta1/azuremanagedcontrolplane_webhook.go | 14 ++++++++++++--
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/api/v1beta1/azuremanagedcontrolplane_default.go b/api/v1beta1/azuremanagedcontrolplane_default.go
index f4b0cd4f4c6..b8def0f6322 100644
--- a/api/v1beta1/azuremanagedcontrolplane_default.go
+++ b/api/v1beta1/azuremanagedcontrolplane_default.go
@@ -19,6 +19,7 @@ package v1beta1
 import (
 	"encoding/base64"
 	"fmt"
+	"reflect"
 	"strings"
 
 	"golang.org/x/crypto/ssh"
@@ -194,7 +195,7 @@ func (m *AzureManagedControlPlane) setDefaultOIDCIssuerProfile() {
 }
 
 func (m *AzureManagedControlPlane) setDefaultDNSPrefix() {
-	if m.Spec.DNSPrefix == nil {
+	if reflect.ValueOf(m.Spec.DNSPrefix).IsZero() {
 		m.Spec.DNSPrefix = ptr.To(m.Name)
 	}
 }
diff --git a/api/v1beta1/azuremanagedcontrolplane_webhook.go b/api/v1beta1/azuremanagedcontrolplane_webhook.go
index 1e5cc196caf..3a8c853da88 100644
--- a/api/v1beta1/azuremanagedcontrolplane_webhook.go
+++ b/api/v1beta1/azuremanagedcontrolplane_webhook.go
@@ -207,10 +207,20 @@ func (mw *azureManagedControlPlaneWebhook) ValidateUpdate(ctx context.Context, o
 		allErrs = append(allErrs, err)
 	}
 
+	oldDNSPrefix := old.Spec.DNSPrefix
+	newDNSPrefix := m.Spec.DNSPrefix
+	if reflect.ValueOf(oldDNSPrefix).IsZero() {
+		oldDNSPrefix = ptr.To(old.Name)
+	}
+
+	if reflect.ValueOf(newDNSPrefix).IsZero() {
+		newDNSPrefix = ptr.To(m.Name)
+	}
+
 	if err := webhookutils.ValidateImmutable(
 		field.NewPath("Spec", "DNSPrefix"),
-		m.Spec.DNSPrefix,
-		old.Spec.DNSPrefix,
+		oldDNSPrefix,
+		newDNSPrefix,
 	); err != nil {
 		allErrs = append(allErrs, err)
 	}