Modify app impl to contain a reference to apiRegistry.

Store additional, late registered and lazy loaded APIs in the registry as well.
Route paths, route objs and others are collected already on late reg, this adds APIs to be collected also.

Signed-off-by: Jussi Hallila <jussi@hallila.com>

.changeset/great-humans-return.md

@@ -0,0 +1,7 @@
+---
+'@backstage/core-app-api': patch
+---
+
+Store additional, late registered and lazy loaded APIs in the registry as well.
+Route paths, route objs and others are collected already on late reg, this adds APIs to be collected also.
+Enables late registration of plugins into the application and updates ApiHolder when additional plugins have been added in.

packages/core-app-api/src/app/App.tsx

@@ -198,6 +198,7 @@ export class PrivateAppImpl implements BackstageApp {
   private readonly bindRoutes: AppOptions['bindRoutes'];
 
   private readonly identityApi = new AppIdentity();
+  private readonly apiFactoryRegistry: ApiFactoryRegistry;
 
   constructor(options: FullAppOptions) {
     this.apis = options.apis;
@@ -208,6 +209,7 @@ export class PrivateAppImpl implements BackstageApp {
     this.configLoader = options.configLoader;
     this.defaultApis = options.defaultApis;
     this.bindRoutes = options.bindRoutes;
+    this.apiFactoryRegistry = new ApiFactoryRegistry();
   }
 
   getPlugins(): BackstagePlugin<any, any>[] {
@@ -388,17 +390,27 @@ export class PrivateAppImpl implements BackstageApp {
 
   private getApiHolder(): ApiHolder {
     if (this.apiHolder) {
+      // Register additional plugins if they have been added.
+      // Routes and other config options are updated above when children change
+      for (const plugin of this.plugins) {
+        for (const factory of plugin.getApis()) {
+          if (!this.apiFactoryRegistry.get(factory.api)) {
+            this.apiFactoryRegistry.register('default', factory);
+          }
+        }
+      }
+      ApiResolver.validateFactories(
+        this.apiFactoryRegistry,
+        this.apiFactoryRegistry.getAllApis(),
+      );
       return this.apiHolder;
     }
-
-    const registry = new ApiFactoryRegistry();
-
-    registry.register('static', {
+    this.apiFactoryRegistry.register('static', {
       api: appThemeApiRef,
       deps: {},
       factory: () => AppThemeSelector.createWithStorage(this.themes),
     });
-    registry.register('static', {
+    this.apiFactoryRegistry.register('static', {
       api: configApiRef,
       deps: {},
       factory: () => {
@@ -410,7 +422,7 @@ export class PrivateAppImpl implements BackstageApp {
         return this.configApi;
       },
     });
-    registry.register('static', {
+    this.apiFactoryRegistry.register('static', {
       api: identityApiRef,
       deps: {},
       factory: () => this.identityApi,
@@ -418,18 +430,18 @@ export class PrivateAppImpl implements BackstageApp {
 
     // It's possible to replace the feature flag API, but since we must have at least
     // one implementation we add it here directly instead of through the defaultApis.
-    registry.register('default', {
+    this.apiFactoryRegistry.register('default', {
       api: featureFlagsApiRef,
       deps: {},
       factory: () => new LocalStorageFeatureFlags(),
     });
     for (const factory of this.defaultApis) {
-      registry.register('default', factory);
+      this.apiFactoryRegistry.register('default', factory);
     }
 
     for (const plugin of this.plugins) {
       for (const factory of plugin.getApis()) {
-        if (!registry.register('default', factory)) {
+        if (!this.apiFactoryRegistry.register('default', factory)) {
           throw new Error(
             `Plugin ${plugin.getId()} tried to register duplicate or forbidden API factory for ${
               factory.api
@@ -440,17 +452,19 @@ export class PrivateAppImpl implements BackstageApp {
     }
 
     for (const factory of this.apis) {
-      if (!registry.register('app', factory)) {
+      if (!this.apiFactoryRegistry.register('app', factory)) {
         throw new Error(
           `Duplicate or forbidden API factory for ${factory.api} in app`,
         );
       }
     }
 
-    ApiResolver.validateFactories(registry, registry.getAllApis());
-
-    this.apiHolder = new ApiResolver(registry);
+    ApiResolver.validateFactories(
+      this.apiFactoryRegistry,
+      this.apiFactoryRegistry.getAllApis(),
+    );
 
+    this.apiHolder = new ApiResolver(this.apiFactoryRegistry);
     return this.apiHolder;
   }