Kubernetes Authorization Explained

Introduction to Kubernetes Authorization

After the authentication phase, the next crucial step in Kubernetes is authorization. It determines what actions a user or entity can perform within the cluster. Kubernetes offers multiple authorization modes, which can be set using the --authorization-mode flag.

Diverse Modes of Kubernetes Authorization

1. Node Authorization: This is a specialized mode that permits the Kubernetes system to execute API operations.
2. Attribute-Based Access Control (ABAC): ABAC, as the name suggests, is based on attributes. Along with setting the ABAC mode, one must also specify the attribute-based authorization policy file. This JSON-based file contains policy objects, each representing a unique policy.
3. Role-Based Access Control (RBAC): RBAC is a more structured approach where roles are created and then bound to specific service accounts or users. It revolves around three primary components: the user, the action (verb), and the object. This mode defines what actions a user can perform on specific Kubernetes objects.
4. Webhook Authorization: In this mode, an external service (webhook) is invoked by the API server to decide if a request should be permitted. It operates as an HTTP callback, triggered upon specific events. For this mode to function, an authorization webhook configuration file is essential.
5. Always Allow & Always Deny Modes: These modes are primarily used for testing purposes. As their names suggest, "Always Allow" approves all requests, while "Always Deny" blocks them.

Configuring Authorization Modes

To activate the desired authorization mode, the API server must be initiated with the `--authorization-mode` flag. This flag ensures that the chosen mode is in effect, safeguarding the cluster`s resources.

Conclusion

Understanding and configuring the right authorization mode is vital for the security and efficiency of a Kubernetes cluster. By mastering these modes, one can ensure a robust and secure Kubernetes environment.