Proxy Buffers EventSources

Is this a bug report?

Yes.

Can you also reproduce the problem with npm 4.x?

Yes.

Environment

1. node -v: v8.8.1
2. npm -v: 5.5.1
3. npm ls react-scripts (if you haven’t ejected): react-scripts@1.0.16

Then, specify:

1. Operating system: Arch Linux
2. Browser and version (if relevant): Firefox 57.0b13

Steps to Reproduce

I’ve got an existing app that I’d like to rewrite using React. The app has a Go backend that provides an EventSource endpoint. I attempted to use the proxy functionality of the development server to route requests for the endpoint to the Go backend.

Example Backend:

func handleEvents(rw http.ResponseWriter, req *http.Request) {
  rw.Header().Set("Content-Type", "text/event-stream")

  for i := 0; true; i++ {
    _, err := fmt.Fprintf(rw, "data: %v\n\n")
    if err != nil {
      break
    }
    rw.(http.Flusher).Flush()
  }
}

Example Frontend:

let es = new EventSource('/events');
es.onmessage = (msg) => {
  console.log(msg);
};

Expected Behavior

It should print a list of numbers in the browser console.

Actual Behavior

Nothing happens at all until I kill the Go backend process, at which point all of the events that the backend had sent arrive suddenly all at once. The EventSource also occasionally calls its onerror callback and then disconnects suddenly for no apparent reason.

Note also that the code works completely fine if I serve the files produced by npm run build directly from the Go backend.

[bogdan-calapod]

After lurking around the internet having the same problem, I think this is related to #966. I think an ok fix would be to toggle webpack dev server’s compression via an ENV variable of some kind.

A workaround might be to enable CORS on the SSE server and connect to it directly

[stale[bot]]

This issue has been automatically marked as stale because it has not had any recent activity. It will be closed in 7 days if no further activity occurs.