feat(catalog): support onProcessingError handler at the catalog plugin

Add the missing support for the `onProcessingError` handler
at the catalog plugin of the new backend system
using the `CatalogProcessingExtensionPoint`.

Related-to: #18301
Signed-off-by: Patrick Jungermann <Patrick.Jungermann@gmail.com>

.changeset/twelve-shirts-buy.md

@@ -0,0 +1,15 @@
+---
+'@backstage/plugin-catalog-backend': patch
+'@backstage/plugin-catalog-node': patch
+---
+
+Add support for `onProcessingError` handler at the catalog plugin (new backend system).
+
+You can use `setOnProcessingErrorHandler` at the `catalogProcessingExtensionPoint`
+as replacement for
+
+```ts
+catalogBuilder.subscribe({
+  onProcessingError: hander,
+});
+```

plugins/catalog-backend/src/service/CatalogPlugin.ts

@@ -17,6 +17,7 @@ import {
   createBackendPlugin,
   coreServices,
 } from '@backstage/backend-plugin-api';
+import { Entity } from '@backstage/catalog-model';
 import { CatalogBuilder, CatalogPermissionRuleInput } from './CatalogBuilder';
 import {
   CatalogAnalysisExtensionPoint,
@@ -40,6 +41,10 @@ class CatalogProcessingExtensionPointImpl
   #processors = new Array<CatalogProcessor>();
   #entityProviders = new Array<EntityProvider>();
   #placeholderResolvers: Record<string, PlaceholderResolver> = {};
+  #onProcessingErrorHandler?: (event: {
+    unprocessedEntity: Entity;
+    errors: Error[];
+  }) => Promise<void> | void;
 
   addProcessor(
     ...processors: Array<CatalogProcessor | Array<CatalogProcessor>>
@@ -61,6 +66,15 @@ class CatalogProcessingExtensionPointImpl
     this.#placeholderResolvers[key] = resolver;
   }
 
+  setOnProcessingErrorHandler(
+    handler: (event: {
+      unprocessedEntity: Entity;
+      errors: Error[];
+    }) => Promise<void> | void,
+  ) {
+    this.#onProcessingErrorHandler = handler;
+  }
+
   get processors() {
     return this.#processors;
   }
@@ -72,6 +86,10 @@ class CatalogProcessingExtensionPointImpl
   get placeholderResolvers() {
     return this.#placeholderResolvers;
   }
+
+  get onProcessingErrorHandler() {
+    return this.#onProcessingErrorHandler;
+  }
 }
 
 class CatalogAnalysisExtensionPointImpl
@@ -162,6 +180,11 @@ export const catalogPlugin = createBackendPlugin({
           scheduler,
           logger: winstonLogger,
         });
+        if (processingExtensions.onProcessingErrorHandler) {
+          builder.subscribe({
+            onProcessingError: processingExtensions.onProcessingErrorHandler,
+          });
+        }
         builder.addProcessor(...processingExtensions.processors);
         builder.addEntityProvider(...processingExtensions.entityProviders);
         Object.entries(processingExtensions.placeholderResolvers).forEach(

plugins/catalog-node/api-report-alpha.md

@@ -54,6 +54,13 @@ export interface CatalogProcessingExtensionPoint {
   addProcessor(
     ...processors: Array<CatalogProcessor | Array<CatalogProcessor>>
   ): void;
+  // (undocumented)
+  setOnProcessingErrorHandler(
+    handler: (event: {
+      unprocessedEntity: Entity;
+      errors: Error[];
+    }) => Promise<void> | void,
+  ): void;
 }
 
 // @alpha (undocumented)

plugins/catalog-node/src/extensions.ts

@@ -37,6 +37,12 @@ export interface CatalogProcessingExtensionPoint {
     ...providers: Array<EntityProvider | Array<EntityProvider>>
   ): void;
   addPlaceholderResolver(key: string, resolver: PlaceholderResolver): void;
+  setOnProcessingErrorHandler(
+    handler: (event: {
+      unprocessedEntity: Entity;
+      errors: Error[];
+    }) => Promise<void> | void,
+  ): void;
 }
 
 /**