[WIP] ✨ Add clusterctl changes for cross-ns CC ref

Makefile

@@ -617,7 +617,6 @@ generate-e2e-templates-main: $(KUSTOMIZE)
 	$(KUSTOMIZE) build $(DOCKER_TEMPLATES)/main/cluster-template-topology --load-restrictor LoadRestrictionsNone > $(DOCKER_TEMPLATES)/main/cluster-template-topology.yaml
 	$(KUSTOMIZE) build $(DOCKER_TEMPLATES)/main/cluster-template-ignition --load-restrictor LoadRestrictionsNone > $(DOCKER_TEMPLATES)/main/cluster-template-ignition.yaml
 	$(KUSTOMIZE) build $(DOCKER_TEMPLATES)/main/clusterclass-quick-start-kcp-only --load-restrictor LoadRestrictionsNone > $(DOCKER_TEMPLATES)/main/clusterclass-quick-start-kcp-only.yaml
-
 	$(KUSTOMIZE) build $(INMEMORY_TEMPLATES)/main/cluster-template --load-restrictor LoadRestrictionsNone > $(INMEMORY_TEMPLATES)/main/cluster-template.yaml
 
 .PHONY: generate-metrics-config

api/v1beta1/cluster_types.go

@@ -17,6 +17,7 @@ limitations under the License.
 package v1beta1
 
 import (
+	"cmp"
 	"fmt"
 	"net"
 	"strings"
@@ -509,6 +510,15 @@ type Topology struct {
 	// The name of the ClusterClass object to create the topology.
 	Class string `json:"class"`
 
+	// The namespace of the ClusterClass object to create the topology.
+	// Empty namespace assumes the namespace of the cluster object.
+	// Class namespace changes are not supported by the rebase procedure.
+	// +optional
+	// +kubebuilder:validation:MinLength=1
+	// +kubebuilder:validation:MaxLength=253
+	// +kubebuilder:validation:Pattern="^[a-z0-9](?:[-a-z0-9]*[a-z0-9])?(?:\\.[a-z0-9](?:[-a-z0-9]*[a-z0-9])?)*$"
+	ClassNamespace string `json:"classNamespace,omitempty"`
+
 	// The Kubernetes version of the cluster.
 	Version string `json:"version"`
 
@@ -1037,7 +1047,9 @@ func (c *Cluster) GetClassKey() types.NamespacedName {
 	if c.Spec.Topology == nil {
 		return types.NamespacedName{}
 	}
-	return types.NamespacedName{Namespace: c.GetNamespace(), Name: c.Spec.Topology.Class}
+
+	namespace := cmp.Or(c.Spec.Topology.ClassNamespace, c.Namespace)
+	return types.NamespacedName{Namespace: namespace, Name: c.Spec.Topology.Class}
 }
 
 // GetConditions returns the set of conditions for this object.

api/v1beta1/index/cluster.go

@@ -30,6 +30,8 @@ import (
 const (
 	// ClusterClassNameField is used by the Cluster controller to index Clusters by ClusterClass name.
 	ClusterClassNameField = "spec.topology.class"
+	// ClusterClassNamespaceField is used by the Cluster controller to index Clusters by ClusterClass namespace.
+	ClusterClassNamespaceField = "spec.topology.classNamespace"
 )
 
 // ByClusterClassName adds the cluster class name  index to the
@@ -44,6 +46,18 @@ func ByClusterClassName(ctx context.Context, mgr ctrl.Manager) error {
 	return nil
 }
 
+// ByClusterClassNamespace adds the cluster class namespace index to the
+// managers cache.
+func ByClusterClassNamespace(ctx context.Context, mgr ctrl.Manager) error {
+	if err := mgr.GetCache().IndexField(ctx, &clusterv1.Cluster{},
+		ClusterClassNamespaceField,
+		ClusterByClusterClassClassNamespace,
+	); err != nil {
+		return errors.Wrap(err, "error setting index field")
+	}
+	return nil
+}
+
 // ClusterByClusterClassClassName contains the logic to index Clusters by ClusterClass name.
 func ClusterByClusterClassClassName(o client.Object) []string {
 	cluster, ok := o.(*clusterv1.Cluster)
@@ -55,3 +69,12 @@ func ClusterByClusterClassClassName(o client.Object) []string {
 	}
 	return nil
 }
+
+// ClusterByClusterClassClassNamespace contains the logic to index Clusters by ClusterClass namespace.
+func ClusterByClusterClassClassNamespace(o client.Object) []string {
+	cluster, ok := o.(*clusterv1.Cluster)
+	if !ok {
+		panic(fmt.Sprintf("Expected Cluster but got a %T", o))
+	}
+	return []string{cluster.GetClassKey().Namespace}
+}

api/v1beta1/index/index.go

@@ -39,6 +39,10 @@ func AddDefaultIndexes(ctx context.Context, mgr ctrl.Manager) error {
 		if err := ByClusterClassName(ctx, mgr); err != nil {
 			return err
 		}
+
+		if err := ByClusterClassNamespace(ctx, mgr); err != nil {
+			return err
+		}
 	}
 
 	if feature.Gates.Enabled(feature.MachinePool) {

cmd/clusterctl/client/clusterclass.go

@@ -23,6 +23,8 @@ import (
 	"github.com/pkg/errors"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/klog/v2"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
 	clusterv1 "sigs.k8s.io/cluster-api/api/v1beta1"
@@ -34,7 +36,7 @@ import (
 // addClusterClassIfMissing returns a Template that includes the base template and adds any cluster class definitions that
 // are references in the template. If the cluster class referenced already exists in the cluster it is not added to the
 // template.
-func addClusterClassIfMissing(ctx context.Context, template Template, clusterClassClient repository.ClusterClassClient, clusterClient cluster.Client, targetNamespace string, listVariablesOnly bool) (Template, error) {
+func addClusterClassIfMissing(ctx context.Context, template Template, clusterClassClient repository.ClusterClassClient, clusterClient cluster.Client, listVariablesOnly bool) (Template, error) {
 	classes, err := clusterClassNamesFromTemplate(template)
 	if err != nil {
 		return nil, err
@@ -44,7 +46,7 @@ func addClusterClassIfMissing(ctx context.Context, template Template, clusterCla
 		return template, nil
 	}
 
-	clusterClassesTemplate, err := fetchMissingClusterClassTemplates(ctx, clusterClassClient, clusterClient, classes, targetNamespace, listVariablesOnly)
+	clusterClassesTemplate, err := fetchMissingClusterClassTemplates(ctx, clusterClassClient, clusterClient, classes, listVariablesOnly)
 	if err != nil {
 		return nil, err
 	}
@@ -62,8 +64,8 @@ func addClusterClassIfMissing(ctx context.Context, template Template, clusterCla
 // clusterClassNamesFromTemplate returns the list of ClusterClasses referenced
 // by clusters defined in the template. If not clusters are defined in the template
 // or if no cluster uses a cluster class it returns an empty list.
-func clusterClassNamesFromTemplate(template Template) ([]string, error) {
-	classes := []string{}
+func clusterClassNamesFromTemplate(template Template) ([]types.NamespacedName, error) {
+	classes := []types.NamespacedName{}
 
 	// loop through all the objects and if the object is a cluster
 	// check and see if cluster.spec.topology.class is defined.
@@ -80,14 +82,14 @@ func clusterClassNamesFromTemplate(template Template) ([]string, error) {
 		if cluster.Spec.Topology == nil {
 			continue
 		}
-		classes = append(classes, cluster.GetClassKey().Name)
+		classes = append(classes, cluster.GetClassKey())
 	}
 	return classes, nil
 }
 
 // fetchMissingClusterClassTemplates returns a list of templates for ClusterClasses that do not yet exist
 // in the cluster. If the cluster is not initialized, all the ClusterClasses are added.
-func fetchMissingClusterClassTemplates(ctx context.Context, clusterClassClient repository.ClusterClassClient, clusterClient cluster.Client, classes []string, targetNamespace string, listVariablesOnly bool) (Template, error) {
+func fetchMissingClusterClassTemplates(ctx context.Context, clusterClassClient repository.ClusterClassClient, clusterClient cluster.Client, classes []types.NamespacedName, listVariablesOnly bool) (Template, error) {
 	// first check if the cluster is initialized.
 	// If it is initialized:
 	//    For every ClusterClass check if it already exists in the cluster.
@@ -118,7 +120,7 @@ func fetchMissingClusterClassTemplates(ctx context.Context, clusterClassClient r
 	templates := []repository.Template{}
 	for _, class := range classes {
 		if clusterInitialized {
-			exists, err := clusterClassExists(ctx, c, class, targetNamespace)
+			exists, err := clusterClassExists(ctx, c, class.Name, class.Namespace)
 			if err != nil {
 				return nil, err
 			}
@@ -128,7 +130,7 @@ func fetchMissingClusterClassTemplates(ctx context.Context, clusterClassClient r
 		}
 		// The cluster is either not initialized or the ClusterClass does not yet exist in the cluster.
 		// Fetch the cluster class to install.
-		clusterClassTemplate, err := clusterClassClient.Get(ctx, class, targetNamespace, listVariablesOnly)
+		clusterClassTemplate, err := clusterClassClient.Get(ctx, class.Name, class.Namespace, listVariablesOnly)
 		if err != nil {
 			return nil, errors.Wrapf(err, "failed to get the cluster class template for %q", class)
 		}
@@ -142,7 +144,7 @@ func fetchMissingClusterClassTemplates(ctx context.Context, clusterClassClient r
 				if exists, err := objExists(ctx, c, obj); err != nil {
 					return nil, err
 				} else if exists {
-					return nil, fmt.Errorf("%s(%s) already exists in the cluster", obj.GetName(), obj.GetObjectKind().GroupVersionKind())
+					return nil, fmt.Errorf("%s(%s) already exists in the cluster", klog.KObj(&obj), obj.GetObjectKind().GroupVersionKind())
 				}
 			}
 		}

cmd/clusterctl/client/clusterclass_test.go

@@ -100,6 +100,7 @@ func TestAddClusterClassIfMissing(t *testing.T) {
 		objs                        []client.Object
 		clusterClassTemplateContent []byte
 		targetNamespace             string
+		clusterClassNamespace       string
 		listVariablesOnly           bool
 		wantClusterClassInTemplate  bool
 		wantError                   bool
@@ -114,6 +115,28 @@ func TestAddClusterClassIfMissing(t *testing.T) {
 			wantClusterClassInTemplate:  true,
 			wantError:                   false,
 		},
+		{
+			name:                        "should add the cluster class from a different namespace to the template if cluster is not initialized",
+			clusterInitialized:          false,
+			objs:                        []client.Object{},
+			targetNamespace:             "ns1",
+			clusterClassNamespace:       "ns2",
+			clusterClassTemplateContent: clusterClassYAML("ns2", "dev"),
+			listVariablesOnly:           false,
+			wantClusterClassInTemplate:  true,
+			wantError:                   false,
+		},
+		{
+			name:                        "should add the cluster class form the same explicitly specified namespace to the template if cluster is not initialized",
+			clusterInitialized:          false,
+			objs:                        []client.Object{},
+			targetNamespace:             "ns1",
+			clusterClassNamespace:       "ns1",
+			clusterClassTemplateContent: clusterClassYAML("ns1", "dev"),
+			listVariablesOnly:           false,
+			wantClusterClassInTemplate:  true,
+			wantError:                   false,
+		},
 		{
 			name:                        "should add the cluster class to the template if cluster is initialized and cluster class is not installed",
 			clusterInitialized:          true,
@@ -189,17 +212,21 @@ func TestAddClusterClassIfMissing(t *testing.T) {
 
 			clusterClassClient := repository1.ClusterClasses("v1.0.0")
 
-			clusterWithTopology := []byte(fmt.Sprintf("apiVersion: %s\n", clusterv1.GroupVersion.String()) +
+			clusterWithTopology := fmt.Sprintf("apiVersion: %s\n", clusterv1.GroupVersion.String()) +
 				"kind: Cluster\n" +
 				"metadata:\n" +
 				"  name: cluster-dev\n" +
 				fmt.Sprintf("  namespace: %s\n", tt.targetNamespace) +
 				"spec:\n" +
 				"  topology:\n" +
-				"    class: dev")
+				"    class: dev"
+
+			if tt.clusterClassNamespace != "" {
+				clusterWithTopology = fmt.Sprintf("%s\n    classNamespace: %s", clusterWithTopology, tt.clusterClassNamespace)
+			}
 
 			baseTemplate, err := repository.NewTemplate(repository.TemplateInput{
-				RawArtifact:           clusterWithTopology,
+				RawArtifact:           []byte(clusterWithTopology),
 				ConfigVariablesClient: test.NewFakeVariableClient(),
 				Processor:             yaml.NewSimpleProcessor(),
 				TargetNamespace:       tt.targetNamespace,
@@ -210,13 +237,22 @@ func TestAddClusterClassIfMissing(t *testing.T) {
 			}
 
 			g := NewWithT(t)
-			template, err := addClusterClassIfMissing(ctx, baseTemplate, clusterClassClient, cluster, tt.targetNamespace, tt.listVariablesOnly)
+			template, err := addClusterClassIfMissing(ctx, baseTemplate, clusterClassClient, cluster, tt.listVariablesOnly)
 			if tt.wantError {
 				g.Expect(err).To(HaveOccurred())
 			} else {
 				if tt.wantClusterClassInTemplate {
-					g.Expect(template.Objs()).To(ContainElement(MatchClusterClass("dev", tt.targetNamespace)))
+					if tt.clusterClassNamespace == tt.targetNamespace {
+						g.Expect(template.Objs()).To(ContainElement(MatchClusterClass("dev", tt.targetNamespace)))
+					} else if tt.clusterClassNamespace != "" {
+						g.Expect(template.Objs()).To(ContainElement(MatchClusterClass("dev", tt.clusterClassNamespace)))
+						g.Expect(template.Objs()).ToNot(ContainElement(MatchClusterClass("dev", tt.targetNamespace)))
+					} else {
+						g.Expect(template.Objs()).To(ContainElement(MatchClusterClass("dev", tt.targetNamespace)))
+						g.Expect(template.Objs()).ToNot(ContainElement(MatchClusterClass("dev", tt.clusterClassNamespace)))
+					}
 				} else {
+					g.Expect(template.Objs()).NotTo(ContainElement(MatchClusterClass("dev", tt.clusterClassNamespace)))
 					g.Expect(template.Objs()).NotTo(ContainElement(MatchClusterClass("dev", tt.targetNamespace)))
 				}
 			}

cmd/clusterctl/client/config.go

@@ -344,7 +344,7 @@ func (c *clusterctlClient) getTemplateFromRepository(ctx context.Context, cluste
 
 	clusterClassClient := repo.ClusterClasses(version)
 
-	template, err = addClusterClassIfMissing(ctx, template, clusterClassClient, cluster, targetNamespace, listVariablesOnly)
+	template, err = addClusterClassIfMissing(ctx, template, clusterClassClient, cluster, listVariablesOnly)
 	if err != nil {
 		return nil, err
 	}

cmd/clusterctl/client/repository/template.go

@@ -17,8 +17,6 @@ limitations under the License.
 package repository
 
 import (
-	"fmt"
-
 	"github.com/pkg/errors"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/util/sets"
@@ -172,10 +170,6 @@ func MergeTemplates(templates ...Template) (Template, error) {
 			}
 		}
 
-		if merged.targetNamespace != tmpl.TargetNamespace() {
-			return nil, fmt.Errorf("cannot merge templates with different targetNamespaces")
-		}
-
 		merged.objs = append(merged.objs, tmpl.Objs()...)
 	}
 

cmd/clusterctl/cmd/util.go

@@ -111,6 +111,13 @@ func printVariablesOutput(template client.Template, options client.GetClusterTem
 			} else if val, ok := os.LookupEnv("KUBERNETES_VERSION"); ok {
 				variableMap[name] = ptr.To(val)
 			}
+		case "CLUSTER_CLASS_NAMESPACE":
+			// Namespace name from the cmd flags or from the kubeconfig is used instead of template default.
+			if val, ok := os.LookupEnv("CLUSTER_CLASS_NAMESPACE"); ok {
+				variableMap[name] = ptr.To(val)
+			} else {
+				variableMap[name] = ptr.To("")
+			}
 		}
 
 		if variableMap[name] != nil {