Ignore stale extension config errors based on flag

Signed-off-by: Musaab Elfaqih <musaabe@spotify.com>

packages/frontend-app-api/src/tree/readAppExtensionsConfig.ts

@@ -16,7 +16,6 @@
 
 import { Config } from '@backstage/config';
 import { JsonValue } from '@backstage/types';
-import { FrontendFeature } from '../wiring';
 
 export interface ExtensionParameters {
   id: string;
@@ -27,34 +26,12 @@ export interface ExtensionParameters {
 
 const knownExtensionParameters = ['attachTo', 'disabled', 'config'];
 
-/**
- * Returns a filtered list of extensions based on what is discovered in the
- * provided features.
- */
-export const filterExtensionsByFeatures = (
-  extensions: ExtensionParameters[],
-  features: FrontendFeature[],
-): ExtensionParameters[] => {
-  // Get a list of all extension IDs discovered in the provided features.
-  const discoveredExtensionIds = features.flatMap(feature =>
-    ('extensions' in feature && Array.isArray(feature.extensions)
-      ? feature.extensions
-      : []
-    ).map((extension: { id: string }) => extension.id),
-  );
-
-  return extensions.filter(extension =>
-    discoveredExtensionIds.includes(extension.id),
-  );
-};
-
 // Since we'll never merge arrays in config the config reader context
 // isn't too much of a help. Fall back to manual config reading logic
 // as the Config interface makes it quite hard for us otherwise.
 /** @internal */
 export function readAppExtensionsConfig(
   rootConfig: Config,
-  features: FrontendFeature[] = [],
 ): ExtensionParameters[] {
   const arr = rootConfig.getOptional('app.extensions');
   if (!Array.isArray(arr)) {
@@ -66,11 +43,8 @@ export function readAppExtensionsConfig(
     return [];
   }
 
-  return filterExtensionsByFeatures(
-    arr.map((arrayEntry, arrayIndex) =>
-      expandShorthandExtensionParameters(arrayEntry, arrayIndex),
-    ),
-    features,
+  return arr.map((arrayEntry, arrayIndex) =>
+    expandShorthandExtensionParameters(arrayEntry, arrayIndex),
   );
 }
 

packages/frontend-app-api/src/tree/resolveAppNodeSpecs.ts

@@ -33,12 +33,14 @@ export function resolveAppNodeSpecs(options: {
   builtinExtensions?: Extension<any, any>[];
   parameters?: Array<ExtensionParameters>;
   forbidden?: Set<string>;
+  ignoreStaleExtensionConfig?: boolean;
 }): AppNodeSpec[] {
   const {
     builtinExtensions = [],
     parameters = [],
     forbidden = new Set(),
     features = [],
+    ignoreStaleExtensionConfig = false,
   } = options;
 
   const plugins = features.filter(OpaqueFrontendPlugin.isType);
@@ -202,7 +204,7 @@ export function resolveAppNodeSpecs(options: {
         existing.params.disabled = Boolean(overrideParam.disabled);
       }
       order.set(extensionId, existing);
-    } else {
+    } else if (!ignoreStaleExtensionConfig) {
       throw new Error(`Extension ${extensionId} does not exist`);
     }
   }

packages/frontend-app-api/src/wiring/createSpecializedApp.tsx

@@ -219,8 +219,11 @@ export function createSpecializedApp(options?: {
       builtinExtensions: [
         resolveExtensionDefinition(Root, { namespace: 'root' }),
       ],
-      parameters: readAppExtensionsConfig(config, features),
+      parameters: readAppExtensionsConfig(config),
       forbidden: new Set(['root']),
+      ignoreStaleExtensionConfig: config.getOptionalBoolean(
+        'app.ignoreStaleExtensionConfig',
+      ),
     }),
   );