cmd/k8s-operator: set PreferDualStack on ProxyGroup egress services (#19194)

On dual-stack clusters defaulting to IPv6, the ProxyGroup egress
service only got an IPv6 address, which causes request failures.
Individual egress proxies already set PreferDualStack correctly.

Fixes: #18768

Signed-off-by: Fernando Serboncini <fserb@tailscale.com>

cmd/k8s-operator/egress-services.go

@@ -457,7 +457,8 @@ func (esr *egressSvcsReconciler) clusterIPSvcForEgress(crl map[string]string) *c
 			Labels:       crl,
 		},
 		Spec: corev1.ServiceSpec{
-			Type: corev1.ServiceTypeClusterIP,
+			Type:           corev1.ServiceTypeClusterIP,
+			IPFamilyPolicy: new(corev1.IPFamilyPolicyPreferDualStack),
 		},
 	}
 }

cmd/k8s-operator/egress-services_test.go

@@ -203,8 +203,9 @@ func clusterIPSvc(name string, extNSvc *corev1.Service) *corev1.Service {
 			Labels:       labels,
 		},
 		Spec: corev1.ServiceSpec{
-			Type:  corev1.ServiceTypeClusterIP,
-			Ports: ports,
+			Type:           corev1.ServiceTypeClusterIP,
+			IPFamilyPolicy: new(corev1.IPFamilyPolicyPreferDualStack),
+			Ports:          ports,
 		},
 	}
 }