Extend cluster builtin to include classNamespace

This patch extends the cluster builtins to include the classNamespace of the
Cluster object.

Author: srm09

docs/book/src/tasks/experimental-features/cluster-class/write-clusterclass.md

@@ -609,7 +609,7 @@ spec:
 In addition to variables specified in the ClusterClass, the following builtin variables can be 
 referenced in patches:
 - `builtin.cluster.{name,namespace,uid,metadata.labels,metadata.annotations}`
-- `builtin.cluster.topology.{version,class}`
+- `builtin.cluster.topology.{version,class,classNamespace}`
 - `builtin.cluster.network.{serviceDomain,services,pods,ipFamily}`
     - Note: ipFamily is deprecated and will be removed in a future release. see https://github.com/kubernetes-sigs/cluster-api/issues/7521.
 - `builtin.controlPlane.{replicas,version,name,metadata.labels,metadata.annotations}`

exp/runtime/hooks/api/v1alpha1/topologymutation_variable_types.go

@@ -79,6 +79,10 @@ type ClusterTopologyBuiltins struct {
 	// class is the name of the ClusterClass of the Cluster.
 	// +optional
 	Class string `json:"class,omitempty"`
+
+	// classNamespace is the namespace of the ClusterClass of the Cluster.
+	// +optional
+	ClassNamespace string `json:"classNamespace,omitempty"`
 }
 
 // ClusterNetworkBuiltins represents builtin cluster network variables.

exp/runtime/hooks/api/v1alpha1/zz_generated.openapi.go

@@ -56,8 +56,9 @@ func Global(clusterTopology *clusterv1.Topology, cluster *clusterv1.Cluster, pat
 			Namespace: cluster.Namespace,
 			UID:       cluster.UID,
 			Topology: &runtimehooksv1.ClusterTopologyBuiltins{
-				Version: cluster.Spec.Topology.Version,
-				Class:   cluster.GetClassKey().Name,
+				Version:        cluster.Spec.Topology.Version,
+				Class:          cluster.GetClassKey().Name,
+				ClassNamespace: cluster.GetClassKey().Namespace,
 			},
 		},
 	}

internal/controllers/topology/cluster/patches/variables/variables.go

@@ -107,7 +107,8 @@ func TestGlobal(t *testing.T) {
 						"metadata": {"labels":{"foo":"bar"}, "annotations":{"fizz":"buzz"}},
  						 "topology":{
   						  	"version": "v1.21.1",
- 						   	"class": "clusterClass1"
+							"class": "clusterClass1",
+							"classNamespace": "default"
   						},
   						"network":{
 							"serviceDomain":"cluster.local",
@@ -179,7 +180,8 @@ func TestGlobal(t *testing.T) {
 						"uid": "8a35f406-6b9b-4b78-8c93-a7f878d90623",
  						 "topology":{
   						  	"version": "v1.21.1",
- 						   	"class": "clusterClass1"
+							"class": "clusterClass1",
+							"classNamespace": "default"
   						},
   						"network":{
 							"serviceDomain":"cluster.local",
@@ -250,8 +252,9 @@ func TestGlobal(t *testing.T) {
   						"namespace": "default",
 						"uid": "8a35f406-6b9b-4b78-8c93-a7f878d90623",
  						 "topology":{
-  						  	"version": "v1.21.1",
- 						   	"class": "clusterClass1"
+							"version": "v1.21.1",
+							"class": "clusterClass1",
+							"classNamespace": "default"
   						},
   						"network":{
   						 	"services":["10.10.10.1/24"],
@@ -318,8 +321,9 @@ func TestGlobal(t *testing.T) {
   						"namespace": "default",
 						"uid": "8a35f406-6b9b-4b78-8c93-a7f878d90623",
  						"topology":{
-    						"version": "v1.21.1",
-    						"class": "clusterClass1"
+							"version": "v1.21.1",
+							"class": "clusterClass1",
+							"classNamespace": "default"
   						},
   						"network":{
     						"serviceDomain":"cluster.local",
@@ -382,7 +386,8 @@ func TestGlobal(t *testing.T) {
 						"uid": "8a35f406-6b9b-4b78-8c93-a7f878d90623",
   						"topology":{
 							"version": "v1.21.1",
-   						 	"class": "clusterClass1"
+							"class": "clusterClass1",
+							"classNamespace": "default"
 						}
 					}}`),
 				},

internal/controllers/topology/cluster/patches/variables/variables_test.go

@@ -478,6 +478,7 @@ var builtinVariables = sets.Set[string]{}.Insert(
 	// ClusterTopology builtins.
 	"builtin.cluster.topology",
 	"builtin.cluster.topology.class",
+	"builtin.cluster.topology.classNamespace",
 	"builtin.cluster.topology.version",
 
 	// ClusterNetwork builtins