Google Open-Sources the Common Expression Language for Python

Google has open-sourced CEL-expr-python, an official Python implementation of the Common Expression Language (CEL). Rather than building from scratch, the library wraps Google's production-ready C++ CEL implementation, ensuring semantic consistency and automatic inheritance of future C++ improvements. CEL is a non-Turing complete, side-effect-free expression language designed for fast, safe, and portable policy evaluation — used in systems like Kubernetes and Envoy. It follows a compile-once, evaluate-many model, making it well-suited for feature flags, data validation, dynamic configuration, and runtime rule evaluation. Python developers previously had to rely on community-maintained libraries; this release provides a first-party runtime with an official codelab tutorial available on GitHub.