Allow to set authentication-type for dashboard addon

[David Negreira]

Currently, the default setting for the kubernetes-dashboard authentication is 'basic' as it can be seen here: https://github.com/juju-solutions/cdk-addons/commit/cb7cf523675f1f656b7db8f91c788de37a67a815.

There is no option to set a different authentication type for the dashboard, for example, 'token'.

Raising this issue in order to be able to set an authentication option to the kubernetes-dashboard addon.

[George Kraft (cynerva)]

Per IRC, this is a customer request.

[Jamon Camisso (jamon)]

Having this configurable is pretty important.

A customer was running kubernetes-dashboard 1.8 via the snap, and an automatic snap upgrade to kubernetes-master 1.12.5 (dashboard 1.10) ended up adding '--authentication-mode=basic' to their dashboard configuration.

This change overrode the implicit default, which is token based, and broke their authentication setup for the dashboard.

[Seyeong Kim (seyeongkim)]

I'm also hit this problem.

just link below as freyes mentioned in different site.

- https://github.com/juju-solutions/cdk-addons/pull/82/commits
- https://github.com/juju-solutions/kubernetes/pull/222/commits