Configuring the storage backend

Purgatory can share the state of its circuits between many instances using a redis server.

With this strategy, when a service has been restarted, it starts with the circuit breaker state.

To choose a storage backend, the unit of work has to be configured.

Using asynchronous API

Important

Extra dependency redis is required. can be installed using

pip install "purgatory[redis]"

import httpx
from purgatory import AsyncCircuitBreakerFactory, AsyncRedisUnitOfWork

circuit_breaker = AsyncCircuitBreakerFactory(
   default_threshold=5,
   default_ttl=30,
   exclude=[
      (httpx.HTTPStatusError, lambda exc: exc.response.is_client_error),
   ],
   uow=AsyncRedisUnitOfWork("redis://localhost/0"),
)

await circuit_breaker.initialize()

Using synchronous API

Important

Extra dependency redis is required. can be installed using

pip install "purgatory[redis]"

import requests
from purgatory import SyncCircuitBreakerFactory, SyncRedisUnitOfWork

circuit_breaker = SyncCircuitBreakerFactory(
   default_threshold=5,
   default_ttl=30,
   exclude=[
      (requests.HTTPError, lambda exc: 400 <= exc.response.status_code < 500),
   ],
   uow=SyncRedisUnitOfWork("redis://localhost/0"),
)

Important

When using the AsyncRedisUnitOfWork, the coroutine initialize must be called to initialize the redis connection.

The synchronous client has this method because it is autogenerated, but it cannot not be used.