Running behind nginx: UI can't connect via websocket

[garymm]

Similar to #1396, but not sure if I should post there or start a new one.

I've got zwave-js-ui running in a docker container with ports 8091 and 3000 exposed.
I've got nginx configured and successfully loading the UI, but the UI can't connect via websocket.
I see these errors in the chrome console:

WebSocket connection to 'wss://zwavejs.example.com/socket.io/?token=...' failed: WebSocket is closed before the connection is established.

Here's my nginx configuration:

upstream zwavejs {
  server <redacted>:8091;
}

map $http_upgrade $connection_upgrade {
    default upgrade;
    '' close;
}

server {
  listen              443 ssl;
  server_name         zwavejs.example.com;

  location / {
      proxy_pass         https://zwavejs;
      proxy_read_timeout 120s;
      proxy_redirect off;
      proxy_buffering off;
      proxy_set_header        Host              $host;
      proxy_set_header        X-Real-IP         $remote_addr;
      proxy_set_header        X-Forwarded-For   $proxy_add_x_forwarded_for;
      proxy_set_header        X-Forwarded-Proto $scheme;
      # https://zwave-js.github.io/zwave-js-ui/#/usage/reverse-proxy?id=accessing-from-behind-a-proxy
      proxy_set_header        Upgrade           $http_upgrade;
      proxy_set_header        Connection        $connection_upgrade;
  }
}

I have https enabled in the UI settings, and I've set SSL_CERTIFICATE and SSL_KEY environment variables.
The app prints to stdout that it's using HTTPS and has loaded the cert and key.

I've also tried changing the proxy_pass to http://zwavejs and disabling HTTPS (but keeping HTTPS on nginx), but that didn't work either.

Things work fine when I access it via http://localhost:8091.

Any tips?

[kpine]

One possibility is because you are missing the proxy_http_version 1.1; setting as part of the websocket configuration. It's included in both the ZUI example you have listed, and also Nginx WebSocket proxying docs. According to MDN, the Upgrade header is only valid for HTTP 1.1, and the nginx default is 1.0.

[garymm]

Thanks for taking a look! I tried, but that didn't seem to fix anything.

[kpine]

What if you disable SSL in ZUI now?

[robertsLando]

Here you can find a working example: https://github.com/zwave-js/zwave-js-ui/tree/master/docker/nginx