Unable to connect to websocket server using wss:// about micronaut-core

[jeremyg484]

The same issue occurs in Mironaut version 4.3.6 so it looks like it is not purely related to 4.4.0 version ⚠️

Are we doing something wrong or do we miss some configuration for WSS?

@iNviNho I don't think (yet) that you're doing anything wrong. I have been investigating and was able to reproduce it in multiple Micronaut 4.x versions as well. It seems to be specific to the SSL implementation. I will update as I learn more.

[jeremyg484]

@iNviNho I have tracked it down to an issue with our ALPN implementation. We do not currently support WebSockets over an HTTP 2 connection (as far as I know, Netty does not yet have an official implementation of RFC8441), but we are advertising support for HTTP 2 in the TLS handshake when making the initial connection to the endpoint. I believe that is what is causing the server to drop the connection.

You can work around it for now by setting micronaut.http.client.alpn-modes=http/1.1.

I will need to implement a fix to force the WebSocket client to only advertise HTTP 1.1 in the TLS handshake.

[iNviNho]

Thank you @jeremyg484 .

Setting

micronaut:
  http:
    client:
      alpn-modes: http/1.1

didn't work but setting alpnMode on the @client already makes a difference

@Client(value = "talos-ws", alpnModes = "http/1.1")

after that we got the error

invalid WebSocket Extension handshake for "permessage-deflate; server_no_context_takeover; client_no_context_takeover"

which we fixed by enabling compression

compression:
      enabled: false

and now everything works as expected 🍾

Thank you so far for your assistance!

[jeremyg484]

Note that alpn-modes is an array, so I believe in YAML it would need to be:

micronaut:
  http:
    client:
      alpn-modes: [http/1.1]

[iNviNho]

The same issue occurs in Mironaut version 4.3.6 so it looks like it is not purely related to 4.4.0 version ⚠️

Are we doing something wrong or do we miss some configuration for WSS?