Fail open.
also: fail closed · fail-open · fail-closed · over-allow · under-allowWhat a protective component does when its own dependency fails: allow everything (fail open) or reject everything (fail closed).
the two-minute refresher
- Example: the rate limiter's Redis is down.
- Fail open (over-allow): legitimate users keep working, but you have no protection.
- Fail closed (under-allow): the system is protected, but legitimate users are blocked.
- Choose by what you protect; a hybrid falls back to local limits.