Enabling PSPs

Enabling PSPs is very simple. Adding PodSecurityPolicy to the API server's list of admission controllers will send all newly created Pod objects through the PodSecurityPolicy admission controller. This controller does two things:

• Identifies the best policy: The best policy to use is identified by the capabilities requested by a pod's definition. A pod cannot explicitly state which policy it wants to enforce, only what capabilities it wants.
• Determines whether the Pod's policy is authorized: Once a policy is identified, the admission controller needs to determine whether the creator of the pod or the serviceAccount of the pod is authorized to use that policy.

The combination of these two criteria can lead to unexpected results. The creator of the pod isn't the user that submits the Deployment or StatefulSet definition. There's a controller that watches for Deployment updates and creates a ReplicaSet. There is a controller that...