actra

Actra Python SDK

Action Admission Control for Automated Systems

Deterministic policy engine that decides whether automated actions are allowed before they execute.

The Actra Python SDK provides a simple interface for loading policies and evaluating decisions using the Actra engine written in Rust.

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Runtime Admission Control

The SDK also provides a runtime layer for protecting functions using Actra policies.

If a policy blocks the operation, the function will not execute and a PermissionError will be raised.

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Installation

Install from PyPI:

pip install actra

The package includes a compiled Rust engine, so no Rust toolchain is required during installation.

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Quick Start

@actra.admit()
def refund(amount):
    ...

The rule lives in policy:

rules:
  - id: block_large_refund
    when:
      subject:
        domain: action
        field: amount
      operator: greater_than
      value:
        literal: 1000
    effect: block

Result:

refund(200)   > allowed  
refund(1500)  > blocked by policy

Actra evaluates the policy before the function executes and blocks refunds greater than 1000.

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Design Goals

The Python SDK focuses on:

• simple developer ergonomics
• deterministic policy evaluation
• minimal runtime overhead
• seamless integration with the Rust engine

The heavy lifting is performed by the core engine, ensuring fast and consistent evaluations.

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Architecture

flowchart LR
    subgraph User Code
        U[User Code]
    end
    
    subgraph SDK Layer
        S[Python SDK]
    end

    subgraph Native Bindings
        N[Rust bindings<br/>actra]
    end

    subgraph Core Engine
        C[Actra Engine]
    end

    U --> S --> N --> C

The SDK provides a Python-friendly interface while the core engine handles compilation and evaluation.

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License

Apache License 2.0

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Project

Actra is designed for systems requiring explicit, reproducible control over state-changing operations in automated environments.