From ad88b303b3bf8fcb114b72095559c4c476246d31 Mon Sep 17 00:00:00 2001
From: Jakob Schrettenbrunner <jakob.schrettenbrunner@telekom.de>
Date: Tue, 11 Apr 2023 10:58:32 +0200
Subject: [PATCH] ipam: fix gateway being required for IPAddress

---
 .../ipam.cluster.x-k8s.io_ipaddresses.yaml      |  1 -
 exp/ipam/api/v1alpha1/ipaddress_types.go        |  3 ++-
 exp/ipam/internal/webhooks/ipaddress.go         | 17 +++++++++--------
 exp/ipam/internal/webhooks/ipaddress_test.go    |  8 ++++++++
 4 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/config/crd/bases/ipam.cluster.x-k8s.io_ipaddresses.yaml b/config/crd/bases/ipam.cluster.x-k8s.io_ipaddresses.yaml
index cdee9f5a8a0b..81be5e44b689 100644
--- a/config/crd/bases/ipam.cluster.x-k8s.io_ipaddresses.yaml
+++ b/config/crd/bases/ipam.cluster.x-k8s.io_ipaddresses.yaml
@@ -92,7 +92,6 @@ spec:
             required:
             - address
             - claimRef
-            - gateway
             - poolRef
             - prefix
             type: object
diff --git a/exp/ipam/api/v1alpha1/ipaddress_types.go b/exp/ipam/api/v1alpha1/ipaddress_types.go
index 14585552772d..01af31d26769 100644
--- a/exp/ipam/api/v1alpha1/ipaddress_types.go
+++ b/exp/ipam/api/v1alpha1/ipaddress_types.go
@@ -36,7 +36,8 @@ type IPAddressSpec struct {
 	Prefix int `json:"prefix"`
 
 	// Gateway is the network gateway of the network the address is from.
-	Gateway string `json:"gateway"`
+	// +optional
+	Gateway string `json:"gateway,omitempty"`
 }
 
 // +kubebuilder:object:root=true
diff --git a/exp/ipam/internal/webhooks/ipaddress.go b/exp/ipam/internal/webhooks/ipaddress.go
index 45c4f5cf05e9..6cf6b056ae9a 100644
--- a/exp/ipam/internal/webhooks/ipaddress.go
+++ b/exp/ipam/internal/webhooks/ipaddress.go
@@ -123,14 +123,15 @@ func (webhook *IPAddress) validate(ctx context.Context, ip *ipamv1.IPAddress) er
 			))
 	}
 
-	_, err = netip.ParseAddr(ip.Spec.Gateway)
-	if err != nil {
-		allErrs = append(allErrs,
-			field.Invalid(
-				specPath.Child("gateway"),
-				ip.Spec.Gateway,
-				"not a valid IP address",
-			))
+	if ip.Spec.Gateway != "" {
+		if _, err := netip.ParseAddr(ip.Spec.Gateway); err != nil {
+			allErrs = append(allErrs,
+				field.Invalid(
+					specPath.Child("gateway"),
+					ip.Spec.Gateway,
+					"not a valid IP address",
+				))
+		}
 	}
 
 	if ip.Spec.PoolRef.APIGroup == nil {
diff --git a/exp/ipam/internal/webhooks/ipaddress_test.go b/exp/ipam/internal/webhooks/ipaddress_test.go
index 5c8809fa253c..5cdad9a5ddcf 100644
--- a/exp/ipam/internal/webhooks/ipaddress_test.go
+++ b/exp/ipam/internal/webhooks/ipaddress_test.go
@@ -130,6 +130,14 @@ func TestIPAddressValidateCreate(t *testing.T) {
 			extraObjs: []client.Object{claim},
 			expectErr: true,
 		},
+		{
+			name: "an empty gateway should be allowed",
+			ip: getAddress(false, func(addr *ipamv1.IPAddress) {
+				addr.Spec.Gateway = ""
+			}),
+			extraObjs: []client.Object{claim},
+			expectErr: false,
+		},
 		{
 			name: "a pool reference that does not match the claim should be rejected",
 			ip: getAddress(false, func(addr *ipamv1.IPAddress) {