SSE close connection issue with proxy

[swapnil-bhalekar]

Checks

• [X] I understand project setup issues should be asked on StackOverflow or in GitHub Discussions.
• [X] I updated to latest http-proxy-middleware.

Describe the bug (be clear and concise)

When we deploy web application for SSE in argocd with nginx server we are not able close SSE server connection on closing of event stream. For front end we are using Angular 16 and for backend service we are using NodeJS

Step-by-step reproduction instructions

1. From angular we are using event source for calling proxy middleware which will connect to backend services.
 
  this.eventSource = new EventSource("host/event/api");

2)   app.use('/event/*', createProxyMiddleware(options));
  On receiving this request on middleware, it will subscribe to close event.
3) On closing of tab we are calling this.eventSource.close() which should close proxy event.
Its working in local but with argoCD we are not able to receive close event.

Expected behavior (be clear and concise)

It should close SSE connection on closing of event stream when we deploy our application in argoCD. We are able to close SSE event in local machine without using argoCD.

How is http-proxy-middleware used in your project?

const options = {
    target: "{Notification service url}" + "/event/",
    changeOrigin: true,
    logger: console,
    onProxyReq: (proxyReq, req, res) => {
      console.log("On proxy req set custom proxy header")
      res.on('close', () => {
        proxyReq.destroy()
      });
    }
  };

  app.use('/event/*', createProxyMiddleware(options));

What http-proxy-middleware configuration are you using?

const options = {
    target: "{Notification service url}" + "/event/",
    changeOrigin: true,
    logger: console,
    onProxyReq: (proxyReq, req, res) => {
      console.log("On proxy req set custom proxy header")
      res.on('close', () => {
        console.log("On close for proxy res");
        proxyReq.destroy()
      });
    }
  };

What OS/version and node/version are you seeing the problem?

Argo CD: v2.7.2+cbee7e6.dirty  platform: linux/amd64

  node:16-alpine3.16

Additional context (optional)

No response

[chimurai]

Can you try with:

onProxyRes: (proxyRes, req, res) => {
    proxyRes.on('close', () => {
      if (!res.writableEnded) {
        res.destroy();
      }
    });
}

from https://github.com/chimurai/http-proxy-middleware/discussions/765#discussioncomment-2617739

[swapnil-bhalekar]

We have already tried this approach. We are getting this issue when using through nginx . Without nginx its working fine.

[chimurai]

Can you provide a working reproduction of this issue so it can be investigated?