use az.List() to check route existence

staging/src/k8s.io/legacy-cloud-providers/azure/azure_fakes.go

@@ -664,6 +664,7 @@ func (fVMSSC *fakeVirtualMachineScaleSetsClient) UpdateInstances(ctx context.Con
 type fakeRoutesClient struct {
 	mutex     *sync.Mutex
 	FakeStore map[string]map[string]network.Route
+	Calls     []string
 }
 
 func newFakeRoutesClient() *fakeRoutesClient {
@@ -677,6 +678,8 @@ func (fRC *fakeRoutesClient) CreateOrUpdate(ctx context.Context, resourceGroupNa
 	fRC.mutex.Lock()
 	defer fRC.mutex.Unlock()
 
+	fRC.Calls = append(fRC.Calls, "CreateOrUpdate")
+
 	if _, ok := fRC.FakeStore[routeTableName]; !ok {
 		fRC.FakeStore[routeTableName] = make(map[string]network.Route)
 	}
@@ -689,6 +692,8 @@ func (fRC *fakeRoutesClient) Delete(ctx context.Context, resourceGroupName strin
 	fRC.mutex.Lock()
 	defer fRC.mutex.Unlock()
 
+	fRC.Calls = append(fRC.Calls, "Delete")
+
 	if routes, ok := fRC.FakeStore[routeTableName]; ok {
 		if _, ok := routes[routeName]; ok {
 			delete(routes, routeName)

staging/src/k8s.io/legacy-cloud-providers/azure/azure_routes.go

@@ -138,7 +138,7 @@ func (az *Cloud) CreateRoute(ctx context.Context, clusterName string, nameHint s
 	}
 	if unmanaged {
 		if az.ipv6DualStackEnabled {
-			//TODO (khenidak) add support for unmanaged nodes when the feature reaches  beta
+			//TODO (khenidak) add support for unmanaged nodes when the feature reaches beta
 			return fmt.Errorf("unmanaged nodes are not supported in dual stack mode")
 		}
 		klog.V(2).Infof("CreateRoute: omitting unmanaged node %q", kubeRoute.TargetNode)
@@ -184,6 +184,21 @@ func (az *Cloud) CreateRoute(ctx context.Context, clusterName string, nameHint s
 		},
 	}
 
+	actualRoutes, err := az.ListRoutes(ctx, clusterName)
+	if err != nil {
+		klog.V(3).Infof("CreateRoute: creating route: failed(ListRoutes) clusterName= %q instance=%q with error=%v", clusterName, kubeRoute.TargetNode, err)
+		return err
+	}
+
+	for _, actualRoute := range actualRoutes {
+		if strings.EqualFold(actualRoute.Name, kubeRoute.Name) &&
+			strings.EqualFold(string(actualRoute.TargetNode), string(kubeRoute.TargetNode)) &&
+			strings.EqualFold(actualRoute.DestinationCIDR, kubeRoute.DestinationCIDR) {
+			klog.V(2).Infof("CreateRoute: route is already existed and matched, no need to re-create or update")
+			return nil
+		}
+	}
+
 	klog.V(3).Infof("CreateRoute: creating route: instance=%q cidr=%q", kubeRoute.TargetNode, kubeRoute.DestinationCIDR)
 	err = az.CreateOrUpdateRoute(route)
 	if err != nil {

staging/src/k8s.io/legacy-cloud-providers/azure/azure_routes_test.go

@@ -137,6 +137,9 @@ func TestCreateRoute(t *testing.T) {
 	if len(fakeTable.Calls) != 1 || fakeTable.Calls[0] != "Get" {
 		t.Errorf("unexpected calls create if not exists, exists: %v", fakeTable.Calls)
 	}
+	if len(fakeRoutes.Calls) != 1 || fakeRoutes.Calls[0] != "CreateOrUpdate" {
+		t.Errorf("unexpected route calls create if not exists, exists: %v", fakeRoutes.Calls)
+	}
 
 	routeName := mapNodeNameToRouteName(false, route.TargetNode, string(route.DestinationCIDR))
 	routeInfo, found := fakeRoutes.FakeStore[cloud.RouteTableName][routeName]
@@ -154,6 +157,24 @@ func TestCreateRoute(t *testing.T) {
 		t.Errorf("Expected IP address: %s, saw %s", nodeIP, *routeInfo.NextHopIPAddress)
 	}
 
+	// test create again without real creation, clean fakeRoute calls
+	fakeRoutes.Calls = []string{}
+	routeInfo.Name = &routeName
+	route.Name = routeName
+	expectedTable.RouteTablePropertiesFormat = &network.RouteTablePropertiesFormat{
+		Routes: &[]network.Route{routeInfo},
+	}
+	cloud.rtCache.Set(cloud.RouteTableName, &expectedTable)
+
+	err = cloud.CreateRoute(context.TODO(), "cluster", "unused", &route)
+	if err != nil {
+		t.Errorf("unexpected error creating route: %v", err)
+		t.FailNow()
+	}
+	if len(fakeRoutes.Calls) != 0 {
+		t.Errorf("unexpected route calls create if not exists, exists: %v", fakeRoutes.Calls)
+	}
+
 	// test create route for unmanaged nodes.
 	nodeName := "node1"
 	nodeCIDR := "4.3.2.1/24"