From 15f15e4a7121d7eff8d8ae18ec3ef7ac26c0b5f5 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Thu, 5 Jan 2023 14:32:58 +0100
Subject: [PATCH] backend-app-api: reimplement rootHttpRouterFactory with
 internal API

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
---
 packages/backend-app-api/package.json         |  2 +
 .../rootHttpRouter/rootHttpRouterFactory.ts   | 64 ++++++++-----------
 yarn.lock                                     |  2 +
 3 files changed, 31 insertions(+), 37 deletions(-)

diff --git a/packages/backend-app-api/package.json b/packages/backend-app-api/package.json
index 7d56da10f1..8c29b08c9e 100644
--- a/packages/backend-app-api/package.json
+++ b/packages/backend-app-api/package.json
@@ -41,6 +41,7 @@
     "@backstage/plugin-permission-node": "workspace:^",
     "@types/cors": "^2.8.6",
     "@types/express": "^4.17.6",
+    "compression": "^1.7.4",
     "cors": "^2.8.5",
     "express": "^4.17.1",
     "express-promise-router": "^4.1.0",
@@ -54,6 +55,7 @@
   },
   "devDependencies": {
     "@backstage/cli": "workspace:^",
+    "@types/compression": "^1.7.0",
     "@types/fs-extra": "^9.0.3",
     "@types/node-forge": "^1.3.0",
     "@types/stoppable": "^1.1.0"
diff --git a/packages/backend-app-api/src/services/implementations/rootHttpRouter/rootHttpRouterFactory.ts b/packages/backend-app-api/src/services/implementations/rootHttpRouter/rootHttpRouterFactory.ts
index ffe345f0a0..d491663ff8 100644
--- a/packages/backend-app-api/src/services/implementations/rootHttpRouter/rootHttpRouterFactory.ts
+++ b/packages/backend-app-api/src/services/implementations/rootHttpRouter/rootHttpRouterFactory.ts
@@ -18,9 +18,19 @@ import {
   createServiceFactory,
   coreServices,
 } from '@backstage/backend-plugin-api';
-import { Handler } from 'express';
-import { createServiceBuilder } from '@backstage/backend-common';
+import express from 'express';
+import compression from 'compression';
+import cors from 'cors';
+import helmet from 'helmet';
 import { RestrictedIndexedRouter } from './RestrictedIndexedRouter';
+import { readCorsOptions } from './readCorsOptions';
+import { startHttpServer } from '../../../lib/http';
+import { readHelmetOptions } from './readHelmetOptions';
+import {
+  errorHandler,
+  notFoundHandler,
+  requestLoggingHandler,
+} from '@backstage/backend-common';
 
 /**
  * @public
@@ -30,11 +40,6 @@ export type RootHttpRouterFactoryOptions = {
    * The path to forward all unmatched requests to. Defaults to '/api/app'
    */
   indexPath?: string | false;
-
-  /**
-   * Middlewares that are added before all other routes.
-   */
-  middleware?: Handler[];
 };
 
 /** @public */
@@ -42,41 +47,26 @@ export const rootHttpRouterFactory = createServiceFactory({
   service: coreServices.rootHttpRouter,
   deps: {
     config: coreServices.config,
+    logger: coreServices.rootLogger,
     lifecycle: coreServices.rootLifecycle,
   },
-  async factory({ config, lifecycle }, options?: RootHttpRouterFactoryOptions) {
-    const router = new RestrictedIndexedRouter(
-      options?.indexPath ?? '/api/app',
-    );
+  async factory(
+    { config, logger, lifecycle },
+    { indexPath }: RootHttpRouterFactoryOptions = {},
+  ) {
+    const router = new RestrictedIndexedRouter(indexPath ?? '/api/app');
 
-    const service = createServiceBuilder(module).loadConfig(config);
+    const app = express();
 
-    for (const middleware of options?.middleware ?? []) {
-      service.addRouter('', middleware);
-    }
+    app.use(helmet(readHelmetOptions(config.getOptionalConfig('backend'))));
+    app.use(cors(readCorsOptions(config.getOptionalConfig('backend'))));
+    app.use(compression());
+    app.use(requestLoggingHandler(logger));
+    app.use(router.handler());
+    app.use(notFoundHandler());
+    app.use(errorHandler({ logger }));
 
-    service.addRouter('', router.handler());
-
-    const server = await service.start();
-    // Stop method isn't part of the public API, let's fix that once we move the implementation here.
-    const stoppableServer = server as typeof server & {
-      stop: (cb: (error?: Error) => void) => void;
-    };
-
-    lifecycle.addShutdownHook({
-      async fn() {
-        await new Promise<void>((resolve, reject) => {
-          stoppableServer.stop((error?: Error) => {
-            if (error) {
-              reject(error);
-            } else {
-              resolve();
-            }
-          });
-        });
-      },
-      labels: { service: 'rootHttpRouter' },
-    });
+    await startHttpServer(app, { config, logger, lifecycle });
 
     return router;
   },
diff --git a/yarn.lock b/yarn.lock
index 0179e179e2..6409539d39 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3384,11 +3384,13 @@ __metadata:
     "@backstage/config": "workspace:^"
     "@backstage/errors": "workspace:^"
     "@backstage/plugin-permission-node": "workspace:^"
+    "@types/compression": ^1.7.0
     "@types/cors": ^2.8.6
     "@types/express": ^4.17.6
     "@types/fs-extra": ^9.0.3
     "@types/node-forge": ^1.3.0
     "@types/stoppable": ^1.1.0
+    compression: ^1.7.4
     cors: ^2.8.5
     express: ^4.17.1
     express-promise-router: ^4.1.0