CEL

CEL. Common Expression Language (CEL) is Google’s sandboxed, non-Turing-complete expression language designed for high-frequency evaluation in security and policy contexts.

Blurb

Common Expression Language – specification and binary representation - cel-expr/cel-spec

Summary

CEL sits between a simple expression evaluator and a full policy language like Rego (Policy as Code / OPA). For Kubernetes specifically, the native ValidatingAdmissionPolicy integration in 1.26+ is a compelling reason to learn it , it removes the operational burden of running a separate admission webhook. For more complex, cross-cutting policy logic, OPA/Rego via Conftest remains more capable. Assess CEL if you are already invested in the Kubernetes control plane; it will likely become unavoidable there.