Add support to set allocation_pools for subnet

This commit adds API that allows users to set `allocations_pools` in the
subnet created by CAPO. This allows the users to restrict the IP address
ranges that will be allocated automatically by OpenStack when creating
Machines.

Users can utilize this to reserve addresses for VIPs (virtual IPs) or
special nodes that will have predefined addresses and will be created
later.

api/v1alpha6/conversion.go

@@ -154,6 +154,11 @@ var v1alpha8OpenStackClusterRestorer = conversion.RestorerFor[*infrav1.OpenStack
 			return &c.Spec.NetworkMTU
 		},
 	),
+	"allocationPools": conversion.UnconditionalFieldRestorer(
+		func(c *infrav1.OpenStackCluster) *[]infrav1.AllocationPool {
+			return &c.Spec.AllocationPools
+		},
+	),
 	"bastion": conversion.HashedFieldRestorer(
 		func(c *infrav1.OpenStackCluster) **infrav1.Bastion {
 			return &c.Spec.Bastion
@@ -240,6 +245,11 @@ var v1alpha8OpenStackClusterTemplateRestorer = conversion.RestorerFor[*infrav1.O
 			return &c.Spec.Template.Spec.NetworkMTU
 		},
 	),
+	"allocationPools": conversion.UnconditionalFieldRestorer(
+		func(c *infrav1.OpenStackClusterTemplate) *[]infrav1.AllocationPool {
+			return &c.Spec.Template.Spec.AllocationPools
+		},
+	),
 	"bastion": conversion.HashedFieldRestorer(
 		func(c *infrav1.OpenStackClusterTemplate) **infrav1.Bastion {
 			return &c.Spec.Template.Spec.Bastion

api/v1alpha7/conversion.go

@@ -98,6 +98,8 @@ func restorev1alpha8ClusterSpec(previous *infrav1.OpenStackClusterSpec, dst *inf
 
 	dst.DisableExternalNetwork = previous.DisableExternalNetwork
 
+	dst.AllocationPools = previous.AllocationPools
+
 	if len(previous.Subnets) > 1 {
 		dst.Subnets = append(dst.Subnets, previous.Subnets[1:]...)
 	}

api/v1alpha8/openstackcluster_types.go

@@ -63,6 +63,12 @@ type OpenStackClusterSpec struct {
 	// through DNS is required.
 	// +listType=set
 	DNSNameservers []string `json:"dnsNameservers,omitempty"`
+
+	// AllocationPools is an array of AllocationPool objects that will be applied to OpenStack Subnet being created.
+	// If set, OpenStack will only allocate these IPs for Machines. It will still be possible to create ports from
+	// outside of these ranges manually.
+	AllocationPools []AllocationPool `json:"allocationPools,omitempty"`
+
 	// ExternalRouterIPs is an array of externalIPs on the respective subnets.
 	// This is necessary if the router needs a fixed ip in a specific subnet.
 	ExternalRouterIPs []ExternalRouterIPParam `json:"externalRouterIPs,omitempty"`

api/v1alpha8/types.go

@@ -87,6 +87,11 @@ type RouterFilter struct {
 	NotTagsAny  string `json:"notTagsAny,omitempty"`
 }
 
+type AllocationPool struct {
+	Start string `json:"start"`
+	End   string `json:"end"`
+}
+
 type PortOpts struct {
 	// Network is a query for an openstack network that the port will be created or discovered on.
 	// This will fail if the query returns more than one network.

config/crd/bases/infrastructure.cluster.x-k8s.io_openstackclusters.yaml

@@ -4838,6 +4838,22 @@ spec:
           spec:
             description: OpenStackClusterSpec defines the desired state of OpenStackCluster.
             properties:
+              allocationPools:
+                description: |-
+                  AllocationPools is an array of AllocationPool objects that will be applied to OpenStack Subnet being created.
+                  If set, OpenStack will only allocate these IPs for Machines. It will still be possible to create ports from
+                  outside of these ranges manually.
+                items:
+                  properties:
+                    end:
+                      type: string
+                    start:
+                      type: string
+                  required:
+                  - end
+                  - start
+                  type: object
+                type: array
               allowAllInClusterTraffic:
                 description: |-
                   AllowAllInClusterTraffic is only used when managed security groups are in use.

config/crd/bases/infrastructure.cluster.x-k8s.io_openstackclustertemplates.yaml

@@ -2263,6 +2263,22 @@ spec:
                     description: OpenStackClusterSpec defines the desired state of
                       OpenStackCluster.
                     properties:
+                      allocationPools:
+                        description: |-
+                          AllocationPools is an array of AllocationPool objects that will be applied to OpenStack Subnet being created.
+                          If set, OpenStack will only allocate these IPs for Machines. It will still be possible to create ports from
+                          outside of these ranges manually.
+                        items:
+                          properties:
+                            end:
+                              type: string
+                            start:
+                              type: string
+                          required:
+                          - end
+                          - start
+                          type: object
+                        type: array
                       allowAllInClusterTraffic:
                         description: |-
                           AllowAllInClusterTraffic is only used when managed security groups are in use.

docs/book/src/topics/crd-changes/v1alpha7-to-v1alpha8.md

@@ -176,4 +176,8 @@ In v1alpha8, this will be automatically converted to:
 
 `Subnets` allows specifications of maximum two `SubnetFilter` one being IPv4 and the other IPv6. Both subnets must be on the same network. Any filtered subnets will be added to `OpenStackCluster.Status.Network.Subnets`.
 
-When subnets are not specified on `OpenStackCluster` and only the network is, the network is used to identify the subnets to use. If more than two subnets exist in the network, the user must specify which ones to use by defining the `OpenStackCluster.Spec.Subnets` field.
+When subnets are not specified on `OpenStackCluster` and only the network is, the network is used to identify the subnets to use. If more than two subnets exist in the network, the user must specify which ones to use by defining the `OpenStackCluster.Spec.Subnets` field.
+
+####  Addition of allocationPools
+
+In v1alpha8, an `AllocationPools` property is introduced to `OpenStackClusterSpec`. When specified, OpenStack subnet created by CAPO will have the given values set as the `allocation_pools` property. This allows users to make sure OpenStack will not allocate some IP ranges in the subnet automatically. If the subnet is precreated and configured, CAPO will ignore `AllocationPools` property.

pkg/cloud/services/networking/network.go

@@ -254,6 +254,10 @@ func (s *Service) createSubnet(openStackCluster *infrav1.OpenStackCluster, clust
 		Description:    names.GetDescription(clusterName),
 	}
 
+	for _, pool := range openStackCluster.Spec.AllocationPools {
+		opts.AllocationPools = append(opts.AllocationPools, subnets.AllocationPool{Start: pool.Start, End: pool.End})
+	}
+
 	subnet, err := s.client.CreateSubnet(opts)
 	if err != nil {
 		record.Warnf(openStackCluster, "FailedCreateSubnet", "Failed to create subnet %s: %v", name, err)