如何仅针对Googlebot启用Angular Universal SSR？

要实现仅当请求来自Googlebot时启用服务端渲染（SSR），其他请求返回客户端渲染的HTML，只需修改server.ts中的路由处理逻辑，通过检查请求的User Agent来分支处理：

import 'zone.js/node';

import { APP_BASE_HREF } from '@angular/common';
import { ngExpressEngine } from '@nguniversal/express-engine';
import * as express from 'express';
import { existsSync } from 'fs';
import { join } from 'path';

import { AppServerModule } from './src/main.server';

// The Express app is exported so that it can be used by serverless Functions.
export function app(): express.Express {
  const server = express();
  const distFolder = join(process.cwd(), 'dist/browser');
  const indexHtml = existsSync(join(distFolder, 'index.original.html')) ? 'index.original.html' : 'index';

  // Our Universal express-engine
  server.engine('html', ngExpressEngine({
    bootstrap: AppServerModule,
  }));

  server.set('view engine', 'html');
  server.set('views', distFolder);

  // TODO: implement data requests securely
  server.get('/api/**', (req, res) => {
    res.status(404).send('data requests are not yet supported');
  });

  // Serve static files from /browser
  server.get('*.*', express.static(distFolder, {
    maxAge: '1y'
  }));

  // 根据User Agent判断是否启用SSR
  server.get('*', (req, res) => {
    const userAgent = req.get('User-Agent');
    // 检测是否为Googlebot（忽略大小写，覆盖所有变体）
    const isGooglebot = userAgent ? /googlebot/i.test(userAgent) : false;

    if (isGooglebot) {
      // Googlebot请求：使用SSR渲染
      res.render(indexHtml, { req, providers: [{ provide: APP_BASE_HREF, useValue: req.baseUrl }] });
    } else {
      // 非Googlebot请求：返回客户端渲染的HTML
      res.sendFile(join(distFolder, indexHtml + '.html'));
    }
  });

  return server;
}

function run(): void {
  const port = process.env['PORT'] || 4000;

  // Start up the Node server
  const server = app();
  server.listen(port, () => {
    console.log(`Node Express server listening on http://localhost:${port}`);
  });
}

// Webpack will replace 'require' with '__webpack_require__'
// '__non_webpack_require__' is a proxy to Node 'require'
// The below code is to ensure that the server is run only when not requiring the bundle.
declare const __non_webpack_require__: NodeRequire;
const mainModule = __non_webpack_require__.main;
const moduleFilename = mainModule && mainModule.filename || '';
if (moduleFilename === __filename || moduleFilename.includes('iisnode')) {
  run();
}

export * from './src/main.server';

关键逻辑说明 #

• User Agent匹配：正则/googlebot/i会忽略大小写匹配所有Googlebot相关的请求头，覆盖桌面端、移动端等Googlebot变体
• SSR分支：检测到Googlebot时，保留原有Angular Universal的res.render逻辑，完成服务端渲染
• 客户端渲染分支：非Googlebot请求直接返回dist/browser目录下的静态HTML文件，触发客户端Angular应用的加载和渲染

内容的提问来源于stack exchange，提问作者Jason Rich Darmawan