Kubernetes Policy Enforcement: Understanding Pod Security Admission (PSA)

In Kubernetes, security is a key concern, especially as containers and microservices grow in complexity. One of the essential features of Kubernetes for policy enforcement is Pod Security Admission (PSA), which replaces the deprecated Pod Security Policies (PSP). PSA provides a more straightforward and flexible approach to enforce security policies, helping administrators safeguard clusters by ensuring that only compliant pods are allowed to run.

This article will guide you through PSA, the available Pod Security Standards, how to configure them, and how to apply security policies to specific namespaces using labels.

What is Pod Security Admission (PSA)?

PSA is a built-in admission controller introduced in Kubernetes 1.23 to replace Pod Security Policies (PSPs). PSPs had a steep learning curve and could become cumbersome when scaling security policies across various environments. PSA simplifies this process by applying Kubernetes Pod Security Standards based on predefined security levels without needing custom logic for each policy.

With PSA, cluster administrators can restrict the permissions of pods by using labels that correspond to specific Pod Security Standards. PSA operates at the namespace level, enabling better…