Skip validation for clusterCIDR in node ipam controller.

clusterCIDR is passed down from kube_env CLUSTER_IP_RANGE to the flag --cluster-cidr.
We plan not to let GKE to pass down CLUSTER_IP_RANGE to kube-env for the master node.

Author: grayluck

pkg/controller/nodeipam/node_ipam_controller.go

@@ -106,13 +106,12 @@ func NewNodeIpamController(
 		metrics.RegisterMetricAndTrackRateLimiterUsage("node_ipam_controller", kubeClient.CoreV1().RESTClient().GetRateLimiter())
 	}
 
-	if clusterCIDR == nil {
-		klog.Fatal("Controller: Must specify --cluster-cidr if --allocate-node-cidrs is set")
-	}
-	mask := clusterCIDR.Mask
 	if allocatorType != ipam.CloudAllocatorType {
 		// Cloud CIDR allocator does not rely on clusterCIDR or nodeCIDRMaskSize for allocation.
-		if maskSize, _ := mask.Size(); maskSize > nodeCIDRMaskSize {
+		if clusterCIDR == nil {
+			klog.Fatal("Controller: Must specify --cluster-cidr if --allocate-node-cidrs is set")
+		}
+		if maskSize, _ := clusterCIDR.Mask.Size(); maskSize > nodeCIDRMaskSize {
 			klog.Fatal("Controller: Invalid --cluster-cidr, mask size of cluster CIDR must be less than --node-cidr-mask-size")
 		}
 	}

pkg/controller/nodeipam/node_ipam_controller_test.go

@@ -70,7 +70,8 @@ func TestNewNodeIpamControllerWithCIDRMasks(t *testing.T) {
 		{"valid_cloud_allocator", "10.0.0.0/21", "10.1.0.0/21", 24, ipam.CloudAllocatorType, false},
 		{"valid_ipam_from_cluster", "10.0.0.0/21", "10.1.0.0/21", 24, ipam.IPAMFromClusterAllocatorType, false},
 		{"valid_ipam_from_cloud", "10.0.0.0/21", "10.1.0.0/21", 24, ipam.IPAMFromCloudAllocatorType, false},
-		{"invalid_cluster_CIDR", "invalid", "10.1.0.0/21", 24, ipam.CloudAllocatorType, true},
+		{"valid_skip_cluster_CIDR_validation_for_cloud_allocator", "invalid", "10.1.0.0/21", 24, ipam.CloudAllocatorType, false},
+		{"invalid_cluster_CIDR", "invalid", "10.1.0.0/21", 24, ipam.IPAMFromClusterAllocatorType, true},
 		{"valid_CIDR_smaller_than_mask_cloud_allocator", "10.0.0.0/26", "10.1.0.0/21", 24, ipam.CloudAllocatorType, false},
 		{"invalid_CIDR_smaller_than_mask_other_allocators", "10.0.0.0/26", "10.1.0.0/21", 24, ipam.IPAMFromCloudAllocatorType, true},
 	} {