🐛 Skip InboundNatRule reconciliation if no LB is configured

Clusters might be externally managed in which case the apiserver
endpoint might be in a different Azure account or on a different
platform altogether. In this case, there are no inboundnatrules for the
LB to reconcile, so skip doing that if the LB name is empty.

azure/services/inboundnatrules/inboundnatrules.go

@@ -56,9 +56,18 @@ func New(scope InboundNatScope) *Service {
 
 // Reconcile gets/creates/updates an inbound NAT rule.
 func (s *Service) Reconcile(ctx context.Context) error {
-	ctx, _, done := tele.StartSpanWithLogger(ctx, "inboundnatrules.Service.Reconcile")
+	ctx, log, done := tele.StartSpanWithLogger(ctx, "inboundnatrules.Service.Reconcile")
 	defer done()
 
+	if s.Scope.APIServerLBName() == "" {
+		log.V(4).Info("Skipping InboundNatRule reconciliation as the cluster has no LB configured")
+		// Until https://github.com/kubernetes-sigs/cluster-api-provider-azure/issues/1868 is
+		// resolved, this needs to be set for the machine to be able to reach the ready condition:
+		// https://github.com/kubernetes-sigs/cluster-api-provider-azure/pull/2066#discussion_r806150004
+		s.Scope.UpdatePutStatus(infrav1.InboundNATRulesReadyCondition, serviceName, nil)
+		return nil
+	}
+
 	ctx, cancel := context.WithTimeout(ctx, reconciler.DefaultAzureServiceReconcileTimeout)
 	defer cancel()
 

azure/services/inboundnatrules/inboundnatrules_test.go

@@ -124,6 +124,16 @@ func TestReconcileInboundNATRule(t *testing.T) {
 				)
 			},
 		},
+		{
+			name:          "No LB, Nat rule reconciliation is skipped",
+			expectedError: "",
+			expect: func(s *mock_inboundnatrules.MockInboundNatScopeMockRecorder,
+				m *mock_inboundnatrules.MockclientMockRecorder,
+				r *mock_async.MockReconcilerMockRecorder) {
+				s.APIServerLBName().AnyTimes().Return("")
+				s.UpdatePutStatus(infrav1.InboundNATRulesReadyCondition, serviceName, nil)
+			},
+		},
 		{
 			name:          "fail to get existing rules",
 			expectedError: "failed to get existing NAT rules: #: Internal Server Error: StatusCode=500",