stamina: Production-grade Retries Made Easy

Transient failures are common in distributed systems. To make your systems resilient, you need to retry failed operations. But bad retries can make things much worse.

stamina is an opinionated wrapper around the great-but-unopinionated Tenacity package. Our goal is to be as ergonomic as possible, while doing the right thing by default, and minimizing the potential for misuse. It is the result of years of copy-pasting the same configuration over and over again:

• Retry only on certain exceptions – or even a subset of them by introspecting them first using a backoff hook.
• Exponential backoff with jitter between retries.
• Limit the number of retries and total time.
• Automatic async support – including Trio.
• Preserve type hints of the decorated callable.
• Flexible instrumentation with Prometheus, structlog, and standard library's logging support out-of-the-box.
• Dedicated support for testing that allows to globally deactivate retries, or to limit the number of retries and to remove backoffs.

For example:

import httpx

import stamina


@stamina.retry(on=httpx.HTTPError, attempts=3)
def do_it(code: int) -> httpx.Response:
    resp = httpx.get(f"https://httpbin.org/status/{code}")
    resp.raise_for_status()

    return resp

Async callables work use the same API and it's possible to retry arbitrary blocks, too. Check out our tutorial for more examples!

Or, if you prefer video, here's a brief introduction into retries and stamina:

Release Information

Changed

• Passing timeout=0 now raises a warning since it counterintuitively disables all retries. If you explicitly want to disable the timeout, use timeout=None.

Fixed

• _compute_backoff() no longer raises OverflowError when the attempt number exceeds 1024 with a float wait_exp_base. The exponential result is now clamped to wait_max on overflow. #137

Full Changelog →

Credits

stamina is written by Hynek Schlawack and distributed under the terms of the MIT license.

The development is kindly supported by my employer Variomedia AG and all my amazing GitHub Sponsors.

This project would not be possible without the years of incredible work that went into Tenacity.

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