Pure Python Google Common Expression Language (CEL)

Pure Python implementation of Google Common Expression Language, https://opensource.google/projects/cel.

The Common Expression Language (CEL) implements common semantics for expression evaluation, enabling different applications to more easily interoperate.

Key Applications

• Security policy: organization have complex infrastructure and need common tooling to reason about the system as a whole

• Protocols: expressions are a useful data type and require interoperability across programming languages and platforms.

This implementation has minimal dependencies, runs quickly, and can be embedded into Python-based applications. Specifically, one intent is to be part of Cloud Custodian (C7N) as part of the security policy filter.

Interested in the API? There are three interesting topics:

• Application Integration

• CEL-Py API

• Data Structures

The integration into another application isn’t a trivial import.

Contents:

• Installation
• CLI Use of CEL-Python
• Configuration
• Application Integration
  • The Essentials
  • Function Bindings
  • Examples from Go implementation
  • Exceptions and Errors
  • Cloud Custodian
• CEL-Py API
  • Example
  • Another Example
  • Runner
  • InterpretedRunner
  • CompiledRunner
  • Int32Value
  • Environment
  • __main__
  • celtypes
  • evaluation
  • parser
• Data Structures
  • Run-Time
  • CEL Types
• C7N Functions Required
  • Design Principles
  • C7N Context Object
  • CELFilter Design
  • C7N Cache
  • Common C7N Constructs
  • Common/Non-Bool Filters
  • Common/Boolean Filters
  • Singleton/Non-Bool Filters
  • Singleton/Boolean Filters
  • Summary

Indices and tables

• Index

• Module Index

• Search Page