Employing access control webhooks
Kubernetes always provided ways for you to customize access control. In Kubernetes, access control can be denoted as triple-A: Authentication, Authorization, and Admission control. In early versions it was through plugins that required Go programming, installing into your cluster, registration, and other invasive procedures. Now, Kubernetes lets you customize authentication, authorization, and admission control webhooks. Here is the access control workflow:
Figure 15.6: Kubernetes access control workflow
Using an authentication webhook
Kubernetes lets you extend the authentication process by injecting a webhook for bearer tokens. It requires two pieces of information: how to access the remote authentication service and the duration of the authentication decision (it defaults to two minutes).
To provide this information and enable authentication webhooks, start the API server with the following command-line arguments:
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