“ERR_HTTP_HEADERS_SENT：发送到客户端后无法设置标头”，而 http-proxy-middleware 与 https-proxy-agent 结合使用

Question

Node (Express JS) 中间件使用 http-proxy-middleware 来代理客户端（可能是 Chrome 浏览器）和 jira 服务器之间的请求和响应。它还使用 https-proxy-agent 添加代理，因为主机服务器需要代理才能访问 Jira API。

已使用 onProxyReq 更新了请求标头。它在 localhost 中完全可以正常工作，因为它不需要代理，但它会在服务器中引发错误 “ERR_HTTP_HEADERS_SENT:Cannot set headers after they are sent to the client”。

代码实现如下

var express = require("express");
var proxy = require("http-proxy-middleware");
var HttpsProxyAgent = require("https-proxy-agent");

var router = express.Router();
// proxy to connect open network
var proxyServer = "http://myproxy.url:8080";

router.use(
  "/jira",
  proxy({
    target: "https://myJira.url",
    agent: new HttpsProxyAgent(proxyServer),
    secure: false,
    changeOrigin: true,
    onProxyReq: function(proxyReq, req, res) {
      proxyReq.setHeader("user-agent", "XXX");
      proxyReq.setHeader("X-Atlassian-Token", "nocheck");
      console.log(
        "Printing Req HEADERS: " + JSON.stringify(proxyReq.getHeaders())
      );
    },
    onProxyRes: function(proxyRes, req, res) {
      proxyRes.headers["Access-Control-Allow-Origin"] = "*";
    },
    pathRewrite: {
      "^/api/jira/": "/" 
    }
  })
);

module.exports = router;

感谢任何帮助解决它。

Answer 1

http-proxy-middleware 内部使用 http-proxy 模块。

在http-proxy 模块中，有一个关于使用proxyReq（或onProxyReq 用于http-proxy-middleware）作为公司代理的未解决问题：https://github.com/http-party/node-http-proxy/issues/1287

b44x 找到的解决方法是使用http-proxy 模块中的proxy.web 低级方法。

我遇到了同样的问题，我是这样解决的：

const http = require('http');
const httpProxy = require('http-proxy');


// define an agent to proxy request to corporate proxy
const proxyAgent = require('proxy-agent');
// get values from environnement variables and avoid hard-coded values
const corporateProxyUrl = process.env.https_proxy || process.env.HTTPS_PROXY || process.env.http_proxy || process.env.HTTP_PROXY || '';
const agent = corporateProxyUrl ? new proxyAgent(corporateProxyUrl) : false;


const myLocalProxy = httpProxy.createProxyServer({});

const myServer = http.createServer(function(req, res) {

  // change request before it's being sent to target
  delete req.headers.origin;

  myLocalProxy.web(req, res, {
    // instruct 'http-proxy' to forward this request to 'target'
    // using 'agent' to pass through corporate proxy
    target: 'https://www.example.com',
    changeOrigin: true,
    agent: agent,
    toProxy: true,
  });

});

myServer.listen(8003);
console.log('[DEMO] Server: listening on port 8003');