feat(backend): add default root http router config

This change adds a default statically defined root http router service
factory configuration, which can be disabled by setting the environment
variable DISABLE_STATIC_ROOT_HTTP_ROUTER_CONFIG to "true".  When this
value is set to "true" the backend will not add this configuration
statically, which will then allow the service factory configuration to
be provided by a dynamic plugin.  This change also adds a logger
instance to inform the user of all of this as the backend starts up.  If
the variable is not set and a dynamic plugin tries to install a service
factory configuration override, it will fail with an error from the
ServiceRegistry as an attempt to register the same service twice.

Signed-off-by: Stan Lewis <[email protected]>

Author: gashcrumb

packages/backend/src/index.ts

@@ -1,24 +1,58 @@
 import { createBackend } from '@backstage/backend-defaults';
+import { rootHttpRouterServiceFactory } from '@backstage/backend-defaults/rootHttpRouter';
 import { dynamicPluginsFeatureLoader } from '@backstage/backend-dynamic-feature-service';
 import { PackageRoles } from '@backstage/cli-node';
 
 import * as path from 'path';
 
 import { configureCorporateProxyAgent } from './corporate-proxy';
 import { CommonJSModuleLoader } from './loader';
-import { transports } from './logger';
+import { createStaticLogger, transports } from './logger';
 import {
   healthCheckPlugin,
   metricsPlugin,
   pluginIDProviderService,
   rbacDynamicPluginsProvider,
 } from './modules';
 
+// Create a logger to cover logging static initialization tasks
+const staticLogger = createStaticLogger({ service: 'developer-hub-init' });
+staticLogger.info('Starting Developer Hub backend');
+
 // RHIDP-2217: adds support for corporate proxy
 configureCorporateProxyAgent();
 
 const backend = createBackend();
 
+// Install a static root HttpRouterServiceFactory configure function that can
+// be explicitly overridden by the user
+if (
+  (process.env.DISABLE_STATIC_ROOT_HTTP_ROUTER_CONFIG || '').toLowerCase() !==
+  'true'
+) {
+  staticLogger.info('Using static root HttpRouterServiceFactory configuration');
+  backend.add(
+    rootHttpRouterServiceFactory({
+      configure({ app, middleware, routes }) {
+        if (process.env.NODE_ENV === 'development') {
+          app.set('json spaces', 2);
+        }
+        app.use(middleware.helmet());
+        app.use(middleware.cors());
+        app.use(middleware.compression());
+        app.use(middleware.logging());
+        app.use(routes);
+        app.use(middleware.notFound());
+        app.use(middleware.error());
+      },
+    }),
+  );
+} else {
+  staticLogger.warn(
+    'Static HttpRouterServiceFactory configuration disabled, allowing custom HttpRouterServiceFactory configuration provided by a dynamic plugin',
+  );
+}
+
 backend.add(
   dynamicPluginsFeatureLoader({
     schemaLocator(pluginPackage) {

packages/backend/src/logger/customLogger.ts

@@ -1,3 +1,4 @@
+import { WinstonLogger } from '@backstage/backend-defaults/rootLogger';
 import type { Config } from '@backstage/config';
 
 import * as winston from 'winston';
@@ -73,3 +74,18 @@ export const transports = {
     ];
   },
 };
+
+export const createStaticLogger = ({ service }: { service: string }) => {
+  const logger = WinstonLogger.create({
+    meta: {
+      service,
+    },
+    level: process.env.LOG_LEVEL || 'info',
+    format:
+      process.env.NODE_ENV === 'production'
+        ? defaultFormat
+        : WinstonLogger.colorFormat(),
+    transports: transports.log,
+  });
+  return logger;
+};