Websocket support?

[tomciopp]

I have a web application (Elixir/Phoenix) that is sitting behind HaProxy and I am running into issues with enabling websockets and the proxy protocol simultaneously.

In my testing I can run behind the proxy normally and requests/websockets work exactly as you would expect. However, when I enable the proxy protocol I can load the page fine but websockets fail to connect. Is there any extra configuration that I would have to do to support websockets out of the box or do you expect this to work and I am just running into a bug somewhere in the chain. If it is the latter I can put together a demo to show what is going on.

[tomciopp]

Here is an example app that demonstrates the broken behavior. You can switch between master and broken-demo branches to view the problem. The only change is to use ranch_proxy_protocol's modules. The web page will load but the web sockets are not functional.

https://github.com/tomciopp/proxy-protocol-demo

Here is some runtime information on my system:
Operating System: OSX 10.13.3
HA-Proxy version 1.8.4-1deb90d 2018/02/08
Elixir 1.6.3 (compiled with OTP 20)
Erlang 20.3

[ferd]

There should be absolutely zero interference between proxy protocol and websockets since websockets are negotiated over an existing HTTP connection as part of the upgrade header mechanism. If you can serve HTTP, then you can serve websockets as far as the PROXY protocol is concerned.

[tomciopp]

That is indeed my expectation, yet it is still broken.