Description: An admission controller in Kubernetes is a fundamental component that acts as an intermediary for requests sent to the Kubernetes API server. Its primary function is to intercept these requests before the objects are persisted in the system. This allows admission controllers to perform various tasks, such as validating and modifying requests, ensuring they comply with the policies and rules defined by the cluster. Admission controllers can be of two types: mutators, which modify requests before they are processed, and validators, which check that requests are correct and comply with established policies. This ability to intercept and modify requests allows Kubernetes administrators to implement security controls, configuration policies, and other operational rules that are essential for the efficient and secure functioning of clusters. Additionally, admission controllers are extensible, meaning users can develop their own custom controllers to meet specific needs in their environment. In summary, admission controllers are an integral part of the Kubernetes architecture, providing a flexible and powerful mechanism for managing how requests are handled within the cluster.
