I'm more interested in WebSocket, but after reading documentation here, I was surprised when I read that:
The following features are not supported by App Engine flexible environment: HTTP/2 traffic to the backend service, Websockets , HTTP requests that directly access instances
I was planning to build an app with gorilla-websocket, but now that I've read this, I don't know how I could accomplish it. I understand WebSocket is not get supported in App Engine Standard Environment, but why not in the Flexible Environment?
There are other options:
Like the standard environment, the flexible environment does not support websockets. If you need to use websockets you can use Compute Engine or Kubernetes Engine.
as stated here.
You can follow the feature request too.
Update:
Currently websocket support is available for following languages
But it's in beta
Docs: https://cloud.google.com/appengine/docs/flexible/python/using-websockets-and-session-affinity