你可以尝试安装npm包：

npm install prom-client

然后，您可以尝试在Next.js pages目录中创建一个名为prometheus.js的新文件：

import { register, collectDefaultMetrics } from 'prom-client';

// Create a custom counter metric for counting HTTP requests
const httpRequestCount = new Counter({
  name: 'http_requests_total',
  help: 'Total number of HTTP requests',
  labelNames: ['method', 'route', 'statusCode'],
});

// Initialize Prometheus metrics collection
collectDefaultMetrics();

// Export a middleware function to expose a /metrics endpoint
export default function (req, res) {
  res.set('Content-Type', register.contentType);
  res.end(register.metrics());
}

// Export the custom counter metric for use in your application
export { httpRequestCount };

然后导入httpRequestCount：

import { httpRequestCount } from './prometheus';

export default function handler(req, res) {
  // Increment the httpRequestCount metric for this request
  httpRequestCount.inc({
    method: req.method,
    route: req.url,
    statusCode: res.statusCode,
  });

  // Handle the request and send the response
  // ...

在next.config.js文件中为/metrics端点添加路由：

module.exports = {
  async rewrites() {
    return [
      {
        source: '/metrics',
        destination: '/prometheus',
      },
    ];
  },
};

那你就完了！
您可以启动Next.js应用程序并导航到http://localhost:3000/metrics以查看Prometheus指标。