backend-app-api: added index plugin option for http router service

Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Co-authored-by: Johan Haals <johan.haals@gmail.com>
Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/fair-tools-melt.md

@@ -0,0 +1,5 @@
+---
+'@backstage/backend-app-api': patch
+---
+
+Added possibility to configure index plugin of the HTTP router service.

packages/backend-app-api/api-report.md

@@ -58,9 +58,14 @@ export const discoveryFactory: (
 
 // @public (undocumented)
 export const httpRouterFactory: (
-  options?: undefined,
+  options?: HttpRouterFactoryOptions | undefined,
 ) => ServiceFactory<HttpRouterService>;
 
+// @public (undocumented)
+export type HttpRouterFactoryOptions = {
+  indexPlugin?: string;
+};
+
 // @public (undocumented)
 export const loggerFactory: (options?: undefined) => ServiceFactory<Logger>;
 

packages/backend-app-api/src/services/implementations/httpRouterService.ts

@@ -24,6 +24,16 @@ import Router from 'express-promise-router';
 import { Handler } from 'express';
 import { createServiceBuilder } from '@backstage/backend-common';
 
+/**
+ * @public
+ */
+export type HttpRouterFactoryOptions = {
+  /**
+   * The plugin ID used for the index route. Defaults to 'app'
+   */
+  indexPlugin?: string;
+};
+
 /** @public */
 export const httpRouterFactory = createServiceFactory({
   service: httpRouterServiceRef,
@@ -31,8 +41,9 @@ export const httpRouterFactory = createServiceFactory({
     config: configServiceRef,
     plugin: pluginMetadataServiceRef,
   },
-  async factory({ config }) {
+  async factory({ config }, options?: HttpRouterFactoryOptions) {
     const rootRouter = Router();
+    const defaultPluginId = options?.indexPlugin ?? 'app';
 
     const service = createServiceBuilder(module)
       .loadConfig(config)
@@ -42,7 +53,7 @@ export const httpRouterFactory = createServiceFactory({
 
     return async ({ plugin }) => {
       const pluginId = plugin.getId();
-      const path = pluginId ? `/api/${pluginId}` : '';
+      const path = pluginId === defaultPluginId ? '' : `/api/${pluginId}`;
       return {
         use(handler: Handler) {
           rootRouter.use(path, handler);

packages/backend-app-api/src/services/implementations/index.ts

@@ -25,3 +25,4 @@ export { schedulerFactory } from './schedulerService';
 export { tokenManagerFactory } from './tokenManagerService';
 export { urlReaderFactory } from './urlReaderService';
 export { httpRouterFactory } from './httpRouterService';
+export type { HttpRouterFactoryOptions } from './httpRouterService';