Fix review comments: remove schemaDiscovery service

Signed-off-by: David Festal <dfestal@redhat.com>

plugins/app-backend/api-report.md

@@ -4,8 +4,8 @@
 
 ```ts
 import { Config } from '@backstage/config';
+import { ConfigSchema } from '@backstage/config-loader';
 import express from 'express';
-import { JsonObject } from '@backstage/types';
 import { Logger } from 'winston';
 import { PluginDatabaseManager } from '@backstage/backend-common';
 
@@ -14,9 +14,6 @@ export function createRouter(options: RouterOptions): Promise<express.Router>;
 
 // @public (undocumented)
 export interface RouterOptions {
-  additionalSchemas?: {
-    [context: string]: JsonObject;
-  };
   appPackageName: string;
   // (undocumented)
   config: Config;
@@ -24,6 +21,7 @@ export interface RouterOptions {
   disableConfigInjection?: boolean;
   // (undocumented)
   logger: Logger;
+  schema?: ConfigSchema;
   staticFallbackHandler?: express.Handler;
 }
 ```

plugins/app-backend/src/lib/config.ts

@@ -19,7 +19,11 @@ import { resolve as resolvePath } from 'path';
 import { Logger } from 'winston';
 import { AppConfig, Config } from '@backstage/config';
 import { JsonObject } from '@backstage/types';
-import { loadConfigSchema, readEnvConfig } from '@backstage/config-loader';
+import {
+  ConfigSchema,
+  loadConfigSchema,
+  readEnvConfig,
+} from '@backstage/config-loader';
 
 type InjectOptions = {
   appConfigs: AppConfig[];
@@ -74,7 +78,7 @@ type ReadOptions = {
   env: { [name: string]: string | undefined };
   appDistDir: string;
   config: Config;
-  additionalSchemas?: { [context: string]: JsonObject };
+  schema?: ConfigSchema;
 };
 
 /**
@@ -91,10 +95,11 @@ export async function readConfigs(options: ReadOptions): Promise<AppConfig[]> {
     const serializedSchema = await fs.readJson(schemaPath);
 
     try {
-      const schema = await loadConfigSchema({
-        serialized: serializedSchema,
-        additionalSchemas: options.additionalSchemas,
-      });
+      const schema =
+        options.schema ||
+        (await loadConfigSchema({
+          serialized: serializedSchema,
+        }));
 
       const frontendConfigs = await schema.process(
         [{ data: config.get() as JsonObject, context: 'app' }],

plugins/app-backend/src/service/appPlugin.ts

@@ -19,10 +19,13 @@ import {
   coreServices,
   createBackendPlugin,
 } from '@backstage/backend-plugin-api';
-import { schemaDiscoveryServiceRef } from '@backstage/backend-plugin-api/alpha';
 import { createRouter } from './router';
 import { loggerToWinstonLogger } from '@backstage/backend-common';
-import { staticFallbackHandlerExtensionPoint } from '@backstage/plugin-app-node';
+import {
+  configSchemaExtensionPoint,
+  staticFallbackHandlerExtensionPoint,
+} from '@backstage/plugin-app-node';
+import { ConfigSchema } from '@backstage/config-loader';
 
 /**
  * The App plugin is responsible for serving the frontend app bundle and static assets.
@@ -32,6 +35,7 @@ export const appPlugin = createBackendPlugin({
   pluginId: 'app',
   register(env) {
     let staticFallbackHandler: express.Handler | undefined;
+    let schema: ConfigSchema | undefined;
 
     env.registerExtensionPoint(staticFallbackHandlerExtensionPoint, {
       setStaticFallbackHandler(handler) {
@@ -44,17 +48,28 @@ export const appPlugin = createBackendPlugin({
       },
     });
 
+    env.registerExtensionPoint(configSchemaExtensionPoint, {
+      setConfigSchema(configSchema) {
+        if (schema) {
+          throw new Error(
+            'Attempted to set config schema for the app-backend twice',
+          );
+        }
+        schema = configSchema;
+      },
+    });
+
     env.registerInit({
       deps: {
         logger: coreServices.logger,
         config: coreServices.rootConfig,
         database: coreServices.database,
         httpRouter: coreServices.httpRouter,
-        schemaDiscovery: schemaDiscoveryServiceRef,
       },
-      async init({ logger, config, database, httpRouter, schemaDiscovery }) {
+      async init({ logger, config, database, httpRouter }) {
         const appPackageName =
           config.getOptionalString('app.packageName') ?? 'app';
+
         const winstonLogger = loggerToWinstonLogger(logger);
 
         const router = await createRouter({
@@ -63,9 +78,7 @@ export const appPlugin = createBackendPlugin({
           database,
           appPackageName,
           staticFallbackHandler,
-          additionalSchemas: (
-            await schemaDiscovery?.getAdditionalSchemas()
-          )?.schemas,
+          schema,
         });
         httpRouter.use(router);
       },

plugins/app-backend/src/service/router.ts

@@ -37,7 +37,7 @@ import {
   CACHE_CONTROL_NO_CACHE,
   CACHE_CONTROL_REVALIDATE_CACHE,
 } from '../lib/headers';
-import { JsonObject } from '@backstage/types';
+import { ConfigSchema } from '@backstage/config-loader';
 
 // express uses mime v1 while we only have types for mime v2
 type Mime = { lookup(arg0: string): string };
@@ -89,14 +89,10 @@ export interface RouterOptions {
 
   /**
    *
-   * Provides a map of additional config schemas, in addition to the serialized schemas
-   * generated during the application build.
-   * This is useful when additional plugins are dynamically loaded in the application at start,
-   * which were not part of the application build. This option allows feeding the corresponding
-   * JSON schemas.
+   * Provides a ConfigSchema.
    *
    */
-  additionalSchemas?: { [context: string]: JsonObject };
+  schema?: ConfigSchema;
 }
 
 /** @public */
@@ -133,7 +129,7 @@ export async function createRouter(
       config,
       appDistDir,
       env: process.env,
-      additionalSchemas: options.additionalSchemas,
+      schema: options.schema,
     });
 
     injectedConfigPath = await injectConfig({ appConfigs, logger, staticDir });