aiobreaker

aiobreaker is a Python implementation of the Circuit Breaker pattern, described in Michael T. Nygard's book Release It!_.

Circuit breakers exist to allow one subsystem to fail without destroying the entire system. This is done by wrapping dangerous operations (typically integration points) with a component that can circumvent calls when the system is not healthy.

This project is a fork of pybreaker_ by Daniel Fernandes Martins that replaces tornado with native asyncio, originally so I could practice packaging and learn about that shiny new typing package.

.. _Release It!: https://pragprog.com/titles/mnee2/release-it-second-edition/ .. _pybreaker: https://github.com/danielfm/pybreaker

Features

• Configurable list of excluded exceptions (e.g. business exceptions)
• Configurable failure threshold and reset timeout
• Support for several event listeners per circuit breaker
• Can guard generator functions
• Functions and properties for easy monitoring and management
• asyncio support
• Optional redis backing
• Synchronous and asynchronous event listeners

Requirements

All you need is python 3.6 or higher.

Installation

To install, simply download from pypi:

.. code:: bash

pip install aiobreaker

Usage

The first step is to create an instance of CircuitBreaker for each integration point you want to protect against.

.. code:: python

from aiobreaker import CircuitBreaker

# Used in database integration points
db_breaker = CircuitBreaker(fail_max=5, reset_timeout=timedelta(seconds=60))

@db_breaker
async def outside_integration():
    """Hits the api"""
    ...

At that point, go ahead and get familiar with the documentation.