在CloudFront缓存中启用VIEWER_RESPONSE函数，以便通过Lambda函数对响应进行处理。确保在Lambda函数中，必须调用event.response.callback（）以正确处理响应。

代码示例：

1. 开启缓存VIEWER_RESPONSE函数

{
    "FunctionName": "MyFunction",
    "Stage": "DEVELOPMENT",
    "EventType": "viewer-response",
    "IncludeBody": true,
    "IncludeHeaders": true
}

2. 编写Lambda函数

exports.handler = async (event, context, callback) => {
  const response = event.Records[0].cf.response;
  const headers = response.headers;

  headers['x-my-custom-header'] = [{ key: 'X-My-Custom-Header', value: 'HelloWorld' }];

  callback(null, response);
};

3. 在Lambda函数中调用event.response.callback()

exports.handler = async (event, context, callback) => {
  const response = event.Records[0].cf.response;
  const headers = response.headers;

  headers['x-my-custom-header'] = [{ key: 'X-My-Custom-Header', value: 'HelloWorld' }];

  event.response.callback(null, response);
};