Troubles restarting proxied websockets

[cquiroz]

First of all thanks for this project it is working great and I really appreciate your work

I'm working on an applícation that uses websockets and they are proxied through snowpack

I noted that if I restart the server snowpack gets terminated with a message as follow:

/Users/cquiroz/Projects/seqexec/modules/web/client/node_modules/snowpack/lib/commands/dev.js:195
    res.writeHead(status, headers);
        ^

TypeError: res.writeHead is not a function
    at sendResponseError (/Users/cquiroz/Projects/seqexec/modules/web/client/node_modules/snowpack/lib/commands/dev.js:195:9)
    at ProxyServer.DEFAULT_PROXY_ERROR_HANDLER (/Users/cquiroz/Projects/seqexec/modules/web/client/node_modules/snowpack/lib/commands/dev.js:110:5)
    at ProxyServer.emit (/Users/cquiroz/Projects/seqexec/modules/web/client/node_modules/eventemitter3/index.js:204:33)
    at ClientRequest.onOutgoingError (/Users/cquiroz/Projects/seqexec/modules/web/client/node_modules/http-proxy/lib/http-proxy/passes/ws-incoming.js:157:16)
    at ClientRequest.emit (events.js:314:20)
    at Socket.socketErrorListener (_http_client.js:469:9)
    at Socket.emit (events.js:314:20)
    at emitErrorNT (internal/streams/destroy.js:100:8)
    at emitErrorCloseNT (internal/streams/destroy.js:68:3)
    at processTicksAndRejections (internal/process/task_queues.js:80:21)

If you have any ideas to try I'd be happy to test them

[FredKSchott]

you may want to check out experiments.routes which will be the new way to do this in v3.0. This gives you full control over the proxy yourself to handle issues like this: https://www.snowpack.dev/guides/routing#grid-body

[cquiroz]

I mmanaged to get the regular http proxy working with routes but I don't seem to hit the one with ws

My conf is:

const proxyWs = httpProxy.createServer({
  target: "http://localhost:7070",
  ws: true,
});

module.exports = {
  experiments: {
    routes: [
      {
        src: "/api/seqexec/events",
        dest: (req, res) => {
          proxyWs.web(req, res);
        },
      },
      {

I don't seem to reach proxyWs at all

[FredKSchott]

Here's their docs: https://github.com/http-party/node-http-proxy#proxying-websockets maybe this helps? Maybe ws: protocol instead?

[cquiroz]

I suspect it is something before the proxy if I add logging like:

    routes: [
      {
        src: "/api/seqexec/events",
        dest: (req, res) => {
          console.log("WS");
          proxyWs.ws(req, res);
        },
      },
      {

I see the WS message if I do curl but not if I use e.g. wscat

[FredKSchott]

I'm not sure, I'm looking at the code and not sure what could be happening. If we match your route to the URL, it looks like we call the dest() function no matter what.

[JackD83]

@cquiroz could you get the route to work?

I'm trying to get the websocket working in 3.0.11 which only has the routes. I came up with the same configuration you did but its not working either. I suspect that snowpack needs to process the "upgrade" event for the route which it does not looking at the code

[cquiroz]

Nope, I reverted to the old config which works, only it doesn't survive if the backend restart but that's fine a good portion of the time.