`juju dashboard` returns immediately and fails to open port with microk8s controller

[Jon Seager]

When trying to test the Juju Dashboard with a controller on microk8s, the `juju dashboard` command displays the dashboard info, but returns immediately and doesn't open any ports.

I've tried this on Juju 2.8/stable and Juju 2.9/edge in a fresh 20.04 vm and my workstation

```
sudo snap install --classic microk8s
sudo usermod -aG microk8s $(whoami)
newgrp microk8s
microk8s enable dns storage

sudo snap install --classic juju
juju bootstrap microk8s micro
juju add-model testing
juju dashboard
```

The command shows the expected output, but returns immediately:

```
Dashboard 0.3.0 for controller "micro" is enabled at:
  https://localhost:43199/dashboard
Your login credential is:
  username: admin
  password: <blah>
```

Confirm the port isn't open with:

```
ss -tlpn | grep 43199
```

If I check the pod logs for the controller, I can see that the dashboard was installed properly, but there are no other logs concerning the dashboard:

```
ubuntu@dash-test:~$ kubectl -n controller-micro logs controller-0 -c api-server | grep -i dash
Installing Dashboard...

```

Thanks!

[Harry Pidcock (hpidcock)]

I was able to reproduce this on 2.9 with microk8s.

[Thomas Miller (tlmiller)]

PR: https://github.com/juju/juju/pull/13007