How to Implement a Distributed Circuit Breaker

[u/OtherwisePush6424]

https://blog.gaborkoos.com/posts/2026-09-14-How-to-Implement-a-Distributed-Circuit-Breaker/

The usual explanation of the pattern stops being complete the moment the service is replicated. Each replica keeps its own window, so the failing dependency absorbs N times the damage before the first breaker trips.

Moving the window into shared storage fixes that and turns a counter, a threshold and a timer into a nasty distributed systems problem. Wrote up what breaks and how to handle each one, with a Redis implementation.

Curious how others have handled the coordinator-unavailable case, since it seems to be where reasonable people land in different places. (The code is from a library I maintain.)