Subdomain 1.2: Implement container-orchestrated solutions
1.The recommendation API's custom scale rule targets the `order-events` queue, and the queue has been empty for several minutes after a burst of traffic. Given the default scale behavior, how long does Container Apps wait after the queue empties before scaling the app down to zero replicas?
- A.Zero seconds, because Container Apps scales down to zero immediately the instant the queue length reaches zero
- B.300 seconds, matching the default cool down period that must elapse before scaling the last replica down to zero
- C.30 seconds, matching the default polling interval used to check the queue length rather than the cool down window
- D.900 seconds, because Container Apps always waits three times the default cool down period before scaling in fully
Show answer & explanation
Correct answer: B — 300 seconds, matching the default cool down period that must elapse before scaling the last replica down to zero
- A. Container Apps does not scale to zero instantly when the queue empties; it waits out the configured cool down period first, so an immediate drop to zero replicas is not the default behavior.
- B. The cool down period defaults to 300 seconds and only applies when scaling from the final replica down to zero, so KEDA waits five minutes after the queue empties before removing the last replica.
- C. The 30-second value is the default polling interval, which controls how often KEDA checks the queue length, not how long it waits before scaling the last replica to zero.
- D. There is no default behavior that triples the cool down period; the documented default cool down window is simply 300 seconds.