Debugging websocket connection errors

I have a binderhub deployment running on k8s via helm.

I am able to run notebooks on the binder instance, but when I try to connect via juniper I get failures when trying to connect to the websocket.

The container gets launched correctly, but then I get an uninformative error in the browser:
Firefox can’t establish a connection to the server at ws://...

Do I need to configure anything on my binderhub / jupyterhub deployment to enable these connections?

You need to setup CORS similar to what we use for

I think there is a second place it needs to be defined (searching for cors in the repo should get you there).

(make sure to check towards the top of the file for the definition of that YAML reference/anchor thing)