Merge pull request #48797 from FengyunPan/fix-empty-cidr

Automatic merge from submit-queue (batch tested with PRs 48231, 47377, 48797, 49020, 49033)

Fix parsing empty CIDR

Fix #48795
Checking ClusterCIDR and ServiceCIDR before parsing them.

**Release note**:
```release-note
NONE
```

cmd/cloud-controller-manager/app/controllermanager.go

@@ -24,6 +24,7 @@ import (
 	"os"
 	goruntime "runtime"
 	"strconv"
+	"strings"
 	"time"
 
 	clientv1 "k8s.io/api/core/v1"
@@ -209,11 +210,6 @@ func StartControllers(s *options.CloudControllerManagerServer, kubeconfig *restc
 	versionedClient := client("shared-informers")
 	sharedInformers := informers.NewSharedInformerFactory(versionedClient, resyncPeriod(s)())
 
-	_, clusterCIDR, err := net.ParseCIDR(s.ClusterCIDR)
-	if err != nil {
-		glog.Warningf("Unsuccessful parsing of cluster CIDR %v: %v", s.ClusterCIDR, err)
-	}
-
 	// Start the CloudNodeController
 	nodeController := nodecontroller.NewCloudNodeController(
 		sharedInformers.Core().V1().Nodes(),
@@ -244,6 +240,14 @@ func StartControllers(s *options.CloudControllerManagerServer, kubeconfig *restc
 		if routes, ok := cloud.Routes(); !ok {
 			glog.Warning("configure-cloud-routes is set, but cloud provider does not support routes. Will not configure cloud provider routes.")
 		} else {
+			var clusterCIDR *net.IPNet
+			if len(strings.TrimSpace(s.ClusterCIDR)) != 0 {
+				_, clusterCIDR, err = net.ParseCIDR(s.ClusterCIDR)
+				if err != nil {
+					glog.Warningf("Unsuccessful parsing of cluster CIDR %v: %v", s.ClusterCIDR, err)
+				}
+			}
+
 			routeController := routecontroller.New(routes, client("route-controller"), sharedInformers.Core().V1().Nodes(), s.ClusterName, clusterCIDR)
 			go routeController.Run(stop, s.RouteReconciliationPeriod.Duration)
 			time.Sleep(wait.Jitter(s.ControllerStartInterval.Duration, ControllerStartJitter))