fastapi-cb

fastapi-cb 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 aiobreaker by Alexander Lyon that add support for integration with FastAPI.

• Release It!
• pybreaker
• aiobreaker

Features

• Works well with FastAPI framework
• 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 3.8 or higher.

Installation

To install, simply download from pypi:

pip install fastapi_cb

Usage

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

from fastapi_cb 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.