auth: define auth handlers as private hive cell

[mhofstetter]

The "null" auth handler is defined as private hive cell within the auth manager cell. The auth manager collects all provided auth handlers in the value group "authHandlers" - which is a feature provided by hive / uber/dig.

This way, multiple auth handlers can register themselves for a different auth type.

Following auth handlers can depend on other components too, without having the manager as core component to know everything. e.g. ~mtlsAuthHandler -> ~keyProvider (which can be implemented by spiffe/spire or something else.

The authentication interface (auth request & response) needs to be defined and implemented once it's clarified.

[mhofstetter]

/test

[meyskens]

LGTM

[youngnick]

Change itself LGTM, but one question for later: It seems like the drop message will include the type of auth requested, which implies that the type of auth is selectable on a per-CiliumNetworkPolicy basis.

Up until now, we've only really talked about having a single auth method configured per Cilium install. Do we anticipate having multiple auth methods available, and then the Policy chooses one, or is this mainly for testing and using the Null auth provider?

[mhofstetter]

Change itself LGTM, but one question for later: It seems like the drop message will include the type of auth requested, which implies that the type of auth is selectable on a per-CiliumNetworkPolicy basis.

Up until now, we've only really talked about having a single auth method configured per Cilium install. Do we anticipate having multiple auth methods available, and then the Policy chooses one, or is this mainly for testing and using the Null auth provider?

auth type is currently configurable on a per policy basis in the CRD - which provides the possibility to switch between multiple auth types at runtime. therefore also gets passed through datapath and finally letting the manager chose the responsible handler.

but i think we need to discuss this in detail, as this also implies, that all the necessary infrastructure needs to be in place.