Merge pull request #42147 from bowei/ip-alias-2

Automatic merge from submit-queue

Add support for IP aliases for pod IPs (GCP alpha feature)

```release-note
Adds support for allocation of pod IPs via IP aliases.

# Adds KUBE_GCE_ENABLE_IP_ALIASES flag to the cluster up scripts (`kube-{up,down}.sh`).

KUBE_GCE_ENABLE_IP_ALIASES=true will enable allocation of PodCIDR ips
using the ip alias mechanism rather than using routes. This feature is currently
only available on GCE.

## Usage
$ CLUSTER_IP_RANGE=10.100.0.0/16 KUBE_GCE_ENABLE_IP_ALIASES=true bash -x cluster/kube-up.sh

# Adds CloudAllocator to the node CIDR allocator (kubernetes-controller manager).

If CIDRAllocatorType is set to `CloudCIDRAllocator`, then allocation
of CIDR allocation instead is done by the external cloud provider and
the node controller is only responsible for reflecting the allocation
into the node spec.

- Splits off the rangeAllocator from the cidr_allocator.go file.
- Adds cloudCIDRAllocator, which is used when the cloud provider allocates
  the CIDR ranges externally. (GCE support only)
- Updates RBAC permission for node controller to include PATCH
```

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

@@ -477,6 +477,7 @@ func StartControllers(controllers map[string]InitFunc, s *options.CMServer, root
 			serviceCIDR,
 			int(s.NodeCIDRMaskSize),
 			s.AllocateNodeCIDRs,
+			nodecontroller.CIDRAllocatorType(s.CIDRAllocatorType),
 			s.EnableTaintManager,
 			utilfeature.DefaultFeatureGate.Enabled(features.TaintBasedEvictions),
 		)

cmd/kube-controller-manager/app/options/options.go

@@ -188,7 +188,10 @@ func (s *CMServer) AddFlags(fs *pflag.FlagSet, allControllers []string, disabled
 	fs.StringVar(&s.ClusterCIDR, "cluster-cidr", s.ClusterCIDR, "CIDR Range for Pods in cluster.")
 	fs.StringVar(&s.ServiceCIDR, "service-cluster-ip-range", s.ServiceCIDR, "CIDR Range for Services in cluster.")
 	fs.Int32Var(&s.NodeCIDRMaskSize, "node-cidr-mask-size", s.NodeCIDRMaskSize, "Mask size for node cidr in cluster.")
-	fs.BoolVar(&s.AllocateNodeCIDRs, "allocate-node-cidrs", false, "Should CIDRs for Pods be allocated and set on the cloud provider.")
+	fs.BoolVar(&s.AllocateNodeCIDRs, "allocate-node-cidrs", false,
+		"Should CIDRs for Pods be allocated and set on the cloud provider.")
+	fs.StringVar(&s.CIDRAllocatorType, "cidr-allocator-type", "RangeAllocator",
+		"Type of CIDR allocator to use")
 	fs.BoolVar(&s.ConfigureCloudRoutes, "configure-cloud-routes", true, "Should CIDRs allocated by allocate-node-cidrs be configured on the cloud provider.")
 	fs.StringVar(&s.Master, "master", s.Master, "The address of the Kubernetes API server (overrides any value in kubeconfig)")
 	fs.StringVar(&s.Kubeconfig, "kubeconfig", s.Kubeconfig, "Path to kubeconfig file with authorization and master location information.")