Kubernetes admission controllers in 5 minutes

Kubernetes admission controllers are integral to managing and securing Kubernetes clusters by intercepting requests to the Kubernetes API before they are persisted, allowing administrators to enforce policies such as resource limits, pod security, and image security. These controllers, which are built into the kube-apiserver binary and configured by the cluster administrator, ensure that deployments adhere to organizational standards by validating or mutating requests based on defined rules. They can be extended through webhooks, which enable custom functionalities such as image scanning, ensuring that only secure and compliant images are deployed. This extension capability allows organizations to tailor Kubernetes operations to specific security needs, enhancing the cluster's reliability and security. Admission controllers are essential for implementing preventive security measures and can be integrated with third-party tools to further enhance Kubernetes' API functionality.