Resilience is a property of the whole service chain
Your service is only as available as the least resilient thing it needs.
That chain runs outside your organisation: the payment provider, the cloud region, the delivery network, the supplier's API. Perfect engineering inside your own boundary buys you the resilience of whichever external dependency fails first, which is usually the one nobody assessed because it seemed too large to fail.
More on Resilience
- High availability and disaster recovery solve different problemsA part, or the place
- A dependency can be more critical than the applicationThe lighter side goes down
- Manual workarounds have capacity limitsThe pipe gets narrower
- Recovery priorities should follow business outcomesWhose order is it?
- Resilience includes people and suppliersThe shelf runs out
- Failover can fail if never exercisedThe day it is asked