Make port forward local port default to the remote port

[AustinScola]

Which project are you reporting a bug for?

kr8s

What happened?

Synchronous port forwards do not appear to be working. It looks like it is b/c the the start method tries to use run run_forever in a thread. but run_forever is async:

    def start(self):
        """Start a background thread with the port forward running."""
        self._bg_thread = threading.Thread(target=self.run_forever, daemon=True)
        self._bg_thread.start()

Anything else?

No response

[AustinScola]

Hmm, nvm seems to be working I was just missing the local port (which I thought would default to the remote port).

[jacobtomlinson]

Maybe we should rename this issue to "Make port forward local port default to the remote port".

Could you share a code example of exactly the snippet you are using so we can reproduce the same result and write a test for the fix?

[AustinScola]

Sure, the snippet was roughly this:

svc: str = ...
remote_port: int = ...
svc = Service.get(svc)
port_forward = svc.portforward(remote_port=remote_port)
port_forward.start()

I think k8s defaults to having the local port be the same as the remote port but I could be wrong?

[jacobtomlinson]

So I've done a quick check locally with kubectl and observed the following behaviour.

# Start a Pod that is exposing a port
kubectl run nginx --image nginx --port 80

# Port forward and only specify the remote port
kubectl port-forward po/nginx 80
# This binds remote port 80 to port 80 locally

# Port forward and specify an empty local port
kubectl port-forward po/nginx :80
# This binds to a random port locally

# Port forward and specify a local port
kubectl port-forward po/nginx 8080:80
# This binds to port 8080 locally

So the current behaviour in kr8s is the same as kubectl port-forward po/nginx :80. It's not clear to me whether we want to switch that to the kubectl port-forward po/nginx 80 behaviour.

[jacobtomlinson]

After thinking on this a bit I feel if the local_port argument is completely omitted it should match the kubectl behaviour of using the remote_port. Then if it is explicitly set to None it should choose a random high port.

I've opened #506 to fix this.