Configure Websocket at traefik 2?

Hi, can please anybody explain, how can I configure Websocket with Traefik 2?
I did not found any information in Docu.

I found one solution here

traefik.http.middlewares.sslheader.headers.customrequestheaders.X-Forwarded-Proto = https

But i do not have https.

I have proxy for my service
I use the configuration file and want my service to respond to the same request via Websocket.

Thanks for the help.