I am using Apache as a reverse proxy to provide authentication in front of my apps. I'm using mod_proxy_express to dynamically manage how domain names are mapped to applications. The problem I am facing is that, when one of the apps tries to establish a WebSocket connection (through the Upgrade HTTP request), Apache does not allow it/proxy it to the app backend.
Reading Apache docs, how one usually enables this is by setting upgrade=websocket for ProxyPass directive. However, for mod_proxy_express I haven't found a way to set this (or any other ProxyPass parameter). Is there something I am missing here? Some other way to influence how mod_proxy_express proxies requests?