stamina 23.2.0

Production-grade retries made easy.

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. Its 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.
• Exponential backoff with jitter between retries.
• Limit the number of retries and total time.
• Automatic async support.
• Preserve type hints of the decorated callable.
• Flexible instrumentation with Prometheus, structlog, and standard library's logging support out-of-the-box.
• Easy global deactivation for testing.

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!

Release Information

Added

• Instrumentation is now pluggable! You can define your own hooks that are run with retry details whenever a retry is scheduled. The documentation now has a whole chapter on instrumentation. #37

• If structlog is not installed, the scheduled retry is now logged using the standard library logging module by default. #35

Changed

• Tenacity's internal AttemptManager object is no longer exposed to the user. This was an oversight and never documented. stamina.retry_context() now yields instances of stamina.Attempt. #22

• Initialization of instrumentation is now delayed. This means that if there's no retries, there's no startup overhead from importing structlog and prometheus-client. #34

• Some key names in structlog log messages have been renamed to better reflect their meaning (slept → waited_so_far, attempt → retry_num, and error → caused_by). You can rename them back using structlog's structlog.processors.EventRenamer. #35

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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.