get minikube url by asking for it
# config file for testing with minikube-config.yaml
-c.BinderHub.hub_url = 'http://192.168.99.100:30123'
+import subprocess
+minikube_ip = subprocess.check_output(['minikube', 'ip']).decode('utf-8')
+c.BinderHub.hub_url = 'http://{}:30123'.format(minikube_ip)
c.BinderHub.hub_api_token = 'aec7d32df938c0f55e54f09244a350cb29ea612907ed4f07be13d9553d18a8e4'
c.BinderHub.use_registry = False
