Support extending KubernetesCluster in extensions (#4702)

* Support extending KubernetesCluster in extensions

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

* Simplify getItemsByEntityClass

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

* Make apiVersion string.

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

* Improve entity loading for extension custom types.

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

* Improve comment.

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

* Fix lint.

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

* Properly handle loading custom entity in cluster-frame

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

* Avoid .bind with .loadOnClusterRenderer

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

* Fix lint.

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

* Revert style change.

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

* Make loadOnClusterRenderer arrow function again, revert autoInitExtensions change as unnecessary

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

* Remove commented code.

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

* Document extending KubernetesCluster in extension guides.

Signed-off-by: Panu Horsmalahti <phorsmalahti@mirantis.com>

docs/extensions/guides/README.md

@@ -20,6 +20,7 @@ Each guide or code sample includes the following:
 | [Main process extension](main-extension.md) | Main.LensExtension |
 | [Renderer process extension](renderer-extension.md) | Renderer.LensExtension |
 | [Resource stack (cluster feature)](resource-stack.md) | |
+| [Extending KubernetesCluster)](extending-kubernetes-cluster.md) | |
 | [Stores](stores.md) | |
 | [Components](components.md) | |
 | [KubeObjectListLayout](kube-object-list-layout.md) | |

docs/extensions/guides/extending-kubernetes-cluster.md

@@ -0,0 +1,69 @@
+# Extending KubernetesCluster
+
+Extension can specify it's own subclass of Common.Catalog.KubernetesCluster. Extension can also specify a new Category for it in the Catalog.
+
+## Extending Common.Catalog.KubernetesCluster
+
+``` typescript
+import { Common } from "@k8slens/extensions";
+
+// The kind must be different from KubernetesCluster's kind
+export const kind = "ManagedDevCluster";
+
+export class ManagedDevCluster extends Common.Catalog.KubernetesCluster {
+  public static readonly kind = kind;
+
+  public readonly kind = kind;
+}
+```
+
+## Extending Common.Catalog.CatalogCategory
+
+These custom Catalog entities can be added a new Category in the Catalog.
+
+``` typescript
+import { Common } from "@k8slens/extensions";
+import { kind, ManagedDevCluster } from "../entities/ManagedDevCluster";
+
+class ManagedDevClusterCategory extends Common.Catalog.CatalogCategory {
+  public readonly apiVersion = "catalog.k8slens.dev/v1alpha1";
+  public readonly kind = "CatalogCategory";
+  public metadata = {
+    name: "Managed Dev Clusters",
+    icon: ""
+  };
+  public spec: Common.Catalog.CatalogCategorySpec = {
+    group: "entity.k8slens.dev",
+    versions: [
+      {
+        name: "v1alpha1",
+        entityClass: ManagedDevCluster as any,
+      },
+    ],
+    names: {
+      kind
+    },
+  };
+}
+
+export { ManagedDevClusterCategory };
+export type { ManagedDevClusterCategory as ManagedDevClusterCategoryType };
+```
+
+The category needs to be registered in the `onActivate()` method both in main and renderer
+
+``` typescript
+// in main's on onActivate
+Main.Catalog.catalogCategories.add(new ManagedDevClusterCategory());
+```
+
+``` typescript
+// in renderer's on onActivate
+Renderer.Catalog.catalogCategories.add(new ManagedDevClusterCategory());
+```
+
+You can then add the entities to the Catalog as a new source:
+
+``` typescript
+this.addCatalogSource("managedDevClusters", this.managedDevClusters);
+```