Backend & systems·Resilience and failure handling
the permissions service timed out and you had to decide, in advance, whether to let the request through or block it.
Fail open
Also calledfail closed, fail safe, fail secure
The choice of default behaviour when a check cannot be performed: fail open allows, fail closed denies. Availability-critical, low-risk checks fail open; anything protecting money, data or access fails closed. The dangerous case is not choosing, because the default is then whatever the exception handler happens to do.