Extend cluster builtin to include UID

This patch extends the cluster builtins to include the UID of the
Cluster object. This can be used by the runtime extensions or JSON
patches to set owner references on objects owned by the Cluster object.

Signed-off-by: Sagar Muchhal <[email protected]>

Author: srm09

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

@@ -532,7 +532,7 @@ spec:
 
 In addition to variables specified in the ClusterClass, the following builtin variables can be 
 referenced in patches:
-- `builtin.cluster.{name,namespace}`
+- `builtin.cluster.{name,namespace,uid}`
 - `builtin.cluster.topology.{version,class}`
 - `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.

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

@@ -16,6 +16,8 @@ limitations under the License.
 
 package v1alpha1
 
+import "k8s.io/apimachinery/pkg/types"
+
 // BuiltinsName is the name of the builtin variable.
 const BuiltinsName = "builtin"
 
@@ -35,6 +37,9 @@ type ClusterBuiltins struct {
 	// Namespace is the namespace of the cluster.
 	Namespace string `json:"namespace,omitempty"`
 
+	// UID is the unqiue identifier of the cluster.
+	UID types.UID `json:"uid,omitempty"`
+
 	// Topology represents the cluster topology variables.
 	Topology *ClusterTopologyBuiltins `json:"topology,omitempty"`
 

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

@@ -28,6 +28,7 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/apimachinery/pkg/util/uuid"
 	utilfeature "k8s.io/component-base/featuregate/testing"
 	"k8s.io/utils/ptr"
 	. "sigs.k8s.io/controller-runtime/pkg/envtest/komega"
@@ -1073,6 +1074,7 @@ func setupTestObjects() (*scope.ClusterBlueprint, *scope.ClusterState) {
 		ObjectMeta: metav1.ObjectMeta{
 			Name:      "cluster1",
 			Namespace: metav1.NamespaceDefault,
+			UID:       uuid.NewUUID(),
 		},
 		Spec: clusterv1.ClusterSpec{
 			Paused: false,

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

@@ -61,6 +61,7 @@ func Global(clusterTopology *clusterv1.Topology, cluster *clusterv1.Cluster, def
 		Cluster: &runtimehooksv1.ClusterBuiltins{
 			Name:      cluster.Name,
 			Namespace: cluster.Namespace,
+			UID:       cluster.UID,
 			Topology: &runtimehooksv1.ClusterTopologyBuiltins{
 				Version: cluster.Spec.Topology.Version,
 				Class:   cluster.GetClassKey().Name,

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

@@ -25,6 +25,7 @@ import (
 	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/utils/ptr"
 
 	clusterv1 "sigs.k8s.io/cluster-api/api/v1beta1"
@@ -34,6 +35,7 @@ import (
 )
 
 func TestGlobal(t *testing.T) {
+	clusterUID := "8a35f406-6b9b-4b78-8c93-a7f878d90623"
 	tests := []struct {
 		name                        string
 		clusterTopology             *clusterv1.Topology
@@ -68,6 +70,7 @@ func TestGlobal(t *testing.T) {
 				ObjectMeta: metav1.ObjectMeta{
 					Name:      "cluster1",
 					Namespace: metav1.NamespaceDefault,
+					UID:       types.UID(clusterUID),
 				},
 				Spec: clusterv1.ClusterSpec{
 					Topology: &clusterv1.Topology{
@@ -100,6 +103,7 @@ func TestGlobal(t *testing.T) {
 					"cluster":{
 						"name": "cluster1",
   						"namespace": "default",
+						"uid": "8a35f406-6b9b-4b78-8c93-a7f878d90623",
  						 "topology":{
   						  	"version": "v1.21.1",
  						   	"class": "clusterClass1"
@@ -149,6 +153,7 @@ func TestGlobal(t *testing.T) {
 				ObjectMeta: metav1.ObjectMeta{
 					Name:      "cluster1",
 					Namespace: metav1.NamespaceDefault,
+					UID:       types.UID(clusterUID),
 				},
 				Spec: clusterv1.ClusterSpec{
 					Topology: &clusterv1.Topology{
@@ -181,6 +186,7 @@ func TestGlobal(t *testing.T) {
 					"cluster":{
 						"name": "cluster1",
   						"namespace": "default",
+						"uid": "8a35f406-6b9b-4b78-8c93-a7f878d90623",
  						 "topology":{
   						  	"version": "v1.21.1",
  						   	"class": "clusterClass1"
@@ -221,6 +227,7 @@ func TestGlobal(t *testing.T) {
 				ObjectMeta: metav1.ObjectMeta{
 					Name:      "cluster1",
 					Namespace: metav1.NamespaceDefault,
+					UID:       types.UID(clusterUID),
 				},
 				Spec: clusterv1.ClusterSpec{
 					Topology: &clusterv1.Topology{
@@ -252,6 +259,7 @@ func TestGlobal(t *testing.T) {
 					"cluster":{
 						"name": "cluster1",
   						"namespace": "default",
+						"uid": "8a35f406-6b9b-4b78-8c93-a7f878d90623",
  						 "topology":{
   						  	"version": "v1.21.1",
  						   	"class": "clusterClass1"
@@ -291,6 +299,7 @@ func TestGlobal(t *testing.T) {
 				ObjectMeta: metav1.ObjectMeta{
 					Name:      "cluster1",
 					Namespace: metav1.NamespaceDefault,
+					UID:       types.UID(clusterUID),
 				},
 				Spec: clusterv1.ClusterSpec{
 					Topology: &clusterv1.Topology{
@@ -319,6 +328,7 @@ func TestGlobal(t *testing.T) {
 					"cluster":{
   						"name": "cluster1",
   						"namespace": "default",
+						"uid": "8a35f406-6b9b-4b78-8c93-a7f878d90623",
  						"topology":{
     						"version": "v1.21.1",
     						"class": "clusterClass1"
@@ -357,6 +367,7 @@ func TestGlobal(t *testing.T) {
 				ObjectMeta: metav1.ObjectMeta{
 					Name:      "cluster1",
 					Namespace: metav1.NamespaceDefault,
+					UID:       types.UID(clusterUID),
 				},
 				Spec: clusterv1.ClusterSpec{
 					Topology: &clusterv1.Topology{
@@ -381,6 +392,7 @@ func TestGlobal(t *testing.T) {
 					"cluster":{
   						"name": "cluster1",
   						"namespace": "default",
+						"uid": "8a35f406-6b9b-4b78-8c93-a7f878d90623",
   						"topology":{
 							"version": "v1.21.1",
    						 	"class": "clusterClass1"

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

@@ -471,6 +471,7 @@ var builtinVariables = sets.Set[string]{}.Insert(
 	"builtin.cluster",
 	"builtin.cluster.name",
 	"builtin.cluster.namespace",
+	"builtin.cluster.uid",
 
 	// ClusterTopology builtins.
 	"builtin.cluster.topology",