在 ALB 规则中添加目标组以保留 Cookie，并在 Express 后端中添加“withCredentials”选项以发送 Cookie。

ALB 会自动将源 IP 放入请求头中，因此可以通过此方法保持会话状态。下面是示例代码：

在 ALB 规则中：

{
  "Type": "forward",
  "TargetGroupArn": "target-group-arn",
  "ForwardConfig": {
    "TargetGroups": [
      {
        "TargetGroupArn": "ecs-target-group-arn",
        "Weight": 100
      }
    ],
    "TargetGroupStickinessConfig": {
      "Enabled": true,
      "DurationSeconds": 86400
    }
  },
  "Order": 2,
  "Conditions": [
    {
      "Field": "path-pattern",
      "PathPatternConfig": {
        "Values": [
          "/api/*"
        ]
      }
    }
  ]
}

在 Express 后端中：

const express = require('express');
const app = express();

app.use((req, res, next) => {
  res.setHeader('Access-Control-Allow-Origin', 'url-of-react-frontend');
  res.setHeader('Access-Control-Allow-Credentials', true);
  next();
});

app.get('/api/cookie', (req, res) => {
  res.cookie('myCookie', 'cookieValue', { maxAge: 900000, httpOnly: true });
  res.send('Cookie set');
});

app.listen(3000, () => console.log('Server started on port 3000'));

在 React 前端中：

const response = await fetch('/api/cookie', { credentials: 'include' });
const data = await response.text();
console.log(data);