Add translation files to CDN assets (#181650)

## Summary

Part of https://github.com/elastic/kibana/issues/72880

- Generate translation files for all locales (including all internal
plugins) during the CDN asset generation task
- Adapt the `rendering` service to use the translation files from the
CDN if configured/enabled

### How to test

Connect to the serverless project that was created for the PR, and
confirm the translation file is being loaded from the CDN

<img width="907" alt="Screenshot 2024-04-25 at 15 55 23"
src="5a6d9110-2e92-41e5-b066-e792e0015134">

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>

packages/core/http/core-http-server-internal/src/static_assets/static_assets.test.ts

@@ -35,6 +35,19 @@ describe('StaticAssets', () => {
     });
   });
 
+  describe('#isUsingCdn()', () => {
+    it('returns false when the CDN is not configured', () => {
+      staticAssets = new StaticAssets(args);
+      expect(staticAssets.isUsingCdn()).toBe(false);
+    });
+
+    it('returns true when the CDN is configured', () => {
+      args.cdnConfig = CdnConfig.from({ url: 'https://cdn.example.com/test' });
+      staticAssets = new StaticAssets(args);
+      expect(staticAssets.isUsingCdn()).toBe(true);
+    });
+  });
+
   describe('#getPluginAssetHref()', () => {
     it('returns the expected value when CDN is not configured', () => {
       staticAssets = new StaticAssets(args);

packages/core/http/core-http-server-internal/src/static_assets/static_assets.ts

@@ -16,6 +16,11 @@ import {
 
 export interface InternalStaticAssets {
   getHrefBase(): string;
+  /**
+   * Returns true if a CDN has been configured and should be used to serve static assets.
+   * Should only be used in scenarios where different behavior has to be used when CDN is enabled or not.
+   */
+  isUsingCdn(): boolean;
   /**
    * Intended for use by server code rendering UI or generating links to static assets
    * that will ultimately be called from the browser and must respect settings like
@@ -67,6 +72,10 @@ export class StaticAssets implements InternalStaticAssets {
     this.assetsServerPathBase = `/${shaDigest}`;
   }
 
+  public isUsingCdn() {
+    return this.hasCdnHost;
+  }
+
   /**
    * Returns a href (hypertext reference) intended to be used as the base for constructing
    * other hrefs to static assets.

packages/core/http/core-http-server-mocks/src/http_service.mock.ts

@@ -87,6 +87,7 @@ const createInternalStaticAssetsMock = (
   basePath: BasePathMocked,
   cdnUrl: undefined | string = undefined
 ): InternalStaticAssetsMocked => ({
+  isUsingCdn: jest.fn().mockReturnValue(!!cdnUrl),
   getHrefBase: jest.fn().mockReturnValue(cdnUrl ?? basePath.serverBasePath),
   getPluginAssetHref: jest.fn().mockReturnValue(cdnUrl ?? basePath.serverBasePath),
   getPluginServerPath: jest.fn((v, _) => v),

packages/core/i18n/core-i18n-server-internal/index.ts

@@ -8,3 +8,5 @@
 
 export type { I18nConfigType, InternalI18nServicePreboot } from './src';
 export { config, I18nService } from './src';
+export { getKibanaTranslationFiles } from './src/get_kibana_translation_files';
+export { supportedLocale } from './src/constants';

packages/core/i18n/core-i18n-server-internal/src/constants.ts

@@ -0,0 +1,12 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+/**
+ * List of all locales that are officially supported.
+ */
+export const supportedLocale = ['en', 'fr-FR', 'ja-JP', 'zh-CN'];

packages/core/rendering/core-rendering-server-internal/src/rendering_service.test.ts

@@ -258,6 +258,42 @@ function renderTestCases(
       const data = JSON.parse(dom('kbn-injected-metadata').attr('data') ?? '""');
       expect(data.logging).toEqual(loggingConfig);
     });
+
+    it('use the correct translation url when CDN is enabled', async () => {
+      const userSettings = { 'theme:darkMode': { userValue: true } };
+      uiSettings.client.getUserProvided.mockResolvedValue(userSettings);
+
+      const [render, deps] = await getRender();
+
+      (deps.http.staticAssets.getHrefBase as jest.Mock).mockReturnValueOnce('http://foo.bar:1773');
+      (deps.http.staticAssets.isUsingCdn as jest.Mock).mockReturnValueOnce(true);
+
+      const content = await render(createKibanaRequest(), uiSettings, {
+        isAnonymousPage: false,
+      });
+      const dom = load(content);
+      const data = JSON.parse(dom('kbn-injected-metadata').attr('data') ?? '""');
+      expect(data.i18n.translationsUrl).toEqual('http://foo.bar:1773/translations/en.json');
+    });
+
+    it('use the correct translation url when CDN is disabled', async () => {
+      const userSettings = { 'theme:darkMode': { userValue: true } };
+      uiSettings.client.getUserProvided.mockResolvedValue(userSettings);
+
+      const [render, deps] = await getRender();
+
+      (deps.http.staticAssets.getHrefBase as jest.Mock).mockReturnValueOnce('http://foo.bar:1773');
+      (deps.http.staticAssets.isUsingCdn as jest.Mock).mockReturnValueOnce(false);
+
+      const content = await render(createKibanaRequest(), uiSettings, {
+        isAnonymousPage: false,
+      });
+      const dom = load(content);
+      const data = JSON.parse(dom('kbn-injected-metadata').attr('data') ?? '""');
+      expect(data.i18n.translationsUrl).toEqual(
+        '/mock-server-basepath/translations/MOCK_HASH/en.json'
+      );
+    });
   });
 }
 

packages/core/rendering/core-rendering-server-internal/src/rendering_service.tsx

@@ -130,6 +130,7 @@ export class RenderingService {
       packageInfo: this.coreContext.env.packageInfo,
     };
     const staticAssetsHrefBase = http.staticAssets.getHrefBase();
+    const usingCdn = http.staticAssets.isUsingCdn();
     const basePath = http.basePath.get(request);
     const { serverBasePath, publicBaseUrl } = http.basePath;
 
@@ -205,8 +206,14 @@ export class RenderingService {
 
     const loggingConfig = await getBrowserLoggingConfig(this.coreContext.configService);
 
-    const translationHash = i18n.getTranslationHash();
-    const translationsUrl = `${serverBasePath}/translations/${translationHash}/${i18nLib.getLocale()}.json`;
+    const locale = i18nLib.getLocale();
+    let translationsUrl: string;
+    if (usingCdn) {
+      translationsUrl = `${staticAssetsHrefBase}/translations/${locale}.json`;
+    } else {
+      const translationHash = i18n.getTranslationHash();
+      translationsUrl = `${serverBasePath}/translations/${translationHash}/${locale}.json`;
+    }
 
     const filteredPlugins = filterUiPlugins({ uiPlugins, isAnonymousPage });
     const bootstrapScript = isAnonymousPage ? 'bootstrap-anonymous.js' : 'bootstrap.js';
@@ -215,7 +222,7 @@ export class RenderingService {
       uiPublicUrl: `${staticAssetsHrefBase}/ui`,
       bootstrapScriptUrl: `${basePath}/${bootstrapScript}`,
       i18n: i18nLib.translate,
-      locale: i18nLib.getLocale(),
+      locale,
       themeVersion,
       darkMode,
       stylesheetPaths: commonStylesheetPaths,
@@ -239,7 +246,6 @@ export class RenderingService {
         clusterInfo,
         anonymousStatusPage: status?.isStatusPageAnonymous() ?? false,
         i18n: {
-          // TODO: Make this load as part of static assets!
           translationsUrl,
         },
         theme: {

src/dev/build/tasks/create_cdn_assets_task.ts

@@ -12,11 +12,13 @@ import { access } from 'fs/promises';
 import { resolve, dirname } from 'path';
 import { asyncForEach } from '@kbn/std';
 import { Jsonc } from '@kbn/repo-packages';
+import { getKibanaTranslationFiles, supportedLocale } from '@kbn/core-i18n-server-internal';
+import { i18n, i18nLoader } from '@kbn/i18n';
 
 import del from 'del';
 import globby from 'globby';
 
-import { mkdirp, compressTar, Task, copyAll } from '../lib';
+import { mkdirp, compressTar, Task, copyAll, write } from '../lib';
 
 export const CreateCdnAssets: Task = {
   description: 'Creating CDN assets',
@@ -31,9 +33,19 @@ export const CreateCdnAssets: Task = {
     await del(assets);
     await mkdirp(assets);
 
-    // Plugins
-
     const plugins = globby.sync([`${buildSource}/node_modules/@kbn/**/*/kibana.jsonc`]);
+
+    // translation files
+    const pluginPaths = plugins.map((plugin) => resolve(dirname(plugin)));
+    for (const locale of supportedLocale) {
+      const translationFileContent = await generateTranslationFile(locale, pluginPaths);
+      await write(
+        resolve(assets, buildSha, `translations`, `${locale}.json`),
+        translationFileContent
+      );
+    }
+
+    // Plugins static assets
     await asyncForEach(plugins, async (path) => {
       const manifest = Jsonc.parse(readFileSync(path, 'utf8')) as any;
       if (manifest?.plugin?.id) {
@@ -101,3 +113,14 @@ export const CreateCdnAssets: Task = {
     });
   },
 };
+
+async function generateTranslationFile(locale: string, pluginPaths: string[]) {
+  const translationFiles = await getKibanaTranslationFiles(locale, pluginPaths);
+  i18nLoader.registerTranslationFiles(translationFiles);
+  const translations = await i18nLoader.getTranslationsByLocale(locale);
+  i18n.init({
+    locale,
+    ...translations,
+  });
+  return JSON.stringify(i18n.getTranslation());
+}

src/dev/tsconfig.json

@@ -42,5 +42,6 @@
     "@kbn/core-test-helpers-so-type-serializer",
     "@kbn/core-test-helpers-kbn-server",
     "@kbn/dev-proc-runner",
+    "@kbn/core-i18n-server-internal",
   ]
 }