keep uiSettings config validation in NP only

src/core/server/http/http_config.ts

@@ -38,6 +38,7 @@ export const config = {
           validate: match(validBasePathRegex, "must start with a slash, don't end with one"),
         })
       ),
+      defaultRoute: schema.maybe(schema.string()),
       cors: schema.conditional(
         schema.contextRef('dev'),
         true,
@@ -106,6 +107,7 @@ export class HttpConfig {
   public basePath?: string;
   public rewriteBasePath: boolean;
   public publicDir: string;
+  public defaultRoute?: string;
   public ssl: SslConfig;
 
   /**
@@ -123,5 +125,6 @@ export class HttpConfig {
     this.rewriteBasePath = rawConfig.rewriteBasePath;
     this.publicDir = env.staticFilesDir;
     this.ssl = new SslConfig(rawConfig.ssl || {});
+    this.defaultRoute = rawConfig.defaultRoute;
   }
 }

src/core/server/http/http_service.ts

@@ -85,6 +85,17 @@ export type HttpServiceSetup = Omit<HttpServerSetup, 'registerRouter'> & {
     contextName: T,
     provider: RequestHandlerContextProvider<T>
   ) => RequestHandlerContextContainer;
+
+  config: {
+    /**
+     * @internalRemarks
+     * Deprecated part of the server config, provided until
+     * https://github.com/elastic/kibana/issues/40255
+     *
+     * @deprecated
+     * */
+    defaultRoute?: string;
+  };
 };
 
 /** @public */
@@ -152,6 +163,10 @@ export class HttpService implements CoreService<HttpServiceSetup, HttpServiceSta
         contextName: T,
         provider: RequestHandlerContextProvider<T>
       ) => this.requestHandlerContext!.registerContext(pluginOpaqueId, contextName, provider),
+
+      config: {
+        defaultRoute: config.defaultRoute,
+      },
     };
 
     return contract;

src/core/server/server.ts

@@ -92,7 +92,9 @@ export class Server {
       http: httpSetup,
     });
 
-    const uiSettingsSetup = await this.uiSettings.setup({});
+    const uiSettingsSetup = await this.uiSettings.setup({
+      http: httpSetup,
+    });
 
     const coreSetup = {
       context: contextServiceSetup,

src/core/server/ui_settings/ui_settings_config.ts

@@ -25,5 +25,8 @@ export const config = {
   path: 'uiSettings',
   schema: schema.object({
     overrides: schema.object({}, { allowUnknowns: true }),
+    // Deprecation is implemented in LP.
+    // We define schema here not to fail on the validation step.
+    enabled: schema.maybe(schema.boolean()),
   }),
 };

src/core/server/ui_settings/ui_settings_service.ts

@@ -24,11 +24,14 @@ import { CoreContext } from '../core_context';
 import { Logger } from '../logging';
 
 import { SavedObjectsClientContract, SavedObjectAttribute } from '../saved_objects/types';
+import { HttpServiceSetup } from '../http';
 import { UiSettingsConfigType } from './ui_settings_config';
 import { IUiSettingsClient, UiSettingsClient } from './ui_settings_client';
 import { mapToObject } from '../../utils/';
 
-interface SetupDeps {} // eslint-disable-line @typescript-eslint/no-empty-interface
+interface SetupDeps {
+  http: HttpServiceSetup;
+}
 
 export type UiSettingsType = 'json' | 'markdown' | 'number' | 'select' | 'boolean' | 'string';
 
@@ -65,30 +68,20 @@ export class UiSettingsService implements CoreService<UiSettingsServiceSetup> {
 
   public async setup(deps: SetupDeps): Promise<UiSettingsServiceSetup> {
     this.log.debug('Setting up ui settings service');
-    const config = await this.config$.pipe(first()).toPromise();
-    const { overrides } = config;
+    const overrides = await this.getOverrides(deps);
     const { version, buildNum } = this.coreContext.env.packageInfo;
-    const getDefaults = () => mapToObject(this.uiSettingsDefaults);
-    const log = this.log;
+
     return {
-      setDefaults: (values: Record<string, UiSettingsParams>) => {
-        Object.entries(values).forEach(([key, value]) => {
-          // can they change over time?
-          // if (this.uiSettingsDefaults.has(key)) {
-          //   throw new Error(`uiSettingsDefaults for key ${key} has been already set`);
-          // }
-          this.uiSettingsDefaults.set(key, value);
-        });
-      },
-      asScopedToClient(savedObjectsClient: SavedObjectsClientContract) {
+      setDefaults: this.setDefaults.bind(this),
+      asScopedToClient: (savedObjectsClient: SavedObjectsClientContract) => {
         return new UiSettingsClient({
           type: 'config',
           id: version,
           buildNum,
           savedObjectsClient,
-          getDefaults,
+          defaults: mapToObject(this.uiSettingsDefaults),
           overrides,
-          log,
+          log: this.log,
         });
       },
     };
@@ -97,4 +90,28 @@ export class UiSettingsService implements CoreService<UiSettingsServiceSetup> {
   public async start() {}
 
   public async stop() {}
+
+  private setDefaults(values: Record<string, UiSettingsParams> = {}) {
+    Object.entries(values).forEach(([key, value]) => {
+      if (this.uiSettingsDefaults.has(key)) {
+        throw new Error(`uiSettings defaults for key ${key} has been already set`);
+      }
+      this.uiSettingsDefaults.set(key, value);
+    });
+  }
+
+  private async getOverrides(deps: SetupDeps) {
+    const config = await this.config$.pipe(first()).toPromise();
+    const overrides: Record<string, SavedObjectAttribute> = config;
+    // manually implemented deprecation until New platform Config service
+    // supports them https://github.com/elastic/kibana/issues/40255
+    if (typeof deps.http.config.defaultRoute !== 'undefined') {
+      overrides.defaultRoute = deps.http.config.defaultRoute;
+      this.log.warn(
+        'Config key "server.defaultRoute" is deprecated. It has been replaced with "uiSettings.overrides.defaultRoute"'
+      );
+    }
+
+    return overrides;
+  }
 }

src/legacy/server/config/schema.js

@@ -108,9 +108,7 @@ export default () => Joi.object({
     ssl: HANDLED_IN_NEW_PLATFORM,
   }).default(),
 
-  uiSettings: Joi.object().keys({
-    overrides: Joi.object().unknown(true).default()
-  }).default(),
+  uiSettings: HANDLED_IN_NEW_PLATFORM,
 
   logging: Joi.object().keys({
     silent: Joi.boolean().default(false),

src/legacy/server/config/transform_deprecations.js

@@ -95,7 +95,6 @@ const cspRules = (settings, log) => {
 
 const deprecations = [
   //server
-  rename('server.defaultRoute', 'uiSettings.overrides.defaultRoute'),
   unused('server.xsrf.token'),
   unused('uiSettings.enabled'),
   rename('optimize.lazy', 'optimize.watch'),