An application publishes a custom metric named QueueAge to Amazon CloudWatch that records how long the oldest message has waited in a processing queue. When QueueAge stays above a threshold for several minutes, operations want an existing AWS Systems Manager Automation runbook to run on its own and drain the backlog, with no servers polling the metric and no custom bridging code to maintain. Which two components, working together, should connect the metric breach to the runbook? (Select TWO.)
- AA CloudWatch alarm on the QueueAge metric that changes to the ALARM state once the threshold is breached for the configured period. Correct
- BAn Amazon EventBridge rule matching the alarm state change to ALARM, with the Systems Manager Automation runbook configured as the rule target. Correct
- CAn AWS Config rule evaluating QueueAge that marks the resource noncompliant and starts the Automation runbook as its remediation action.
- DA Systems Manager Run Command document pushed to the fleet on a schedule to read QueueAge and decide whether to drain the queue.
- EA Lambda function on a fixed EventBridge Scheduler timetable that queries QueueAge each minute and starts the runbook when the value is high.
Why A is correct: The alarm evaluates the custom metric and produces the ALARM state change that signals the breach, which is the trigger the remediation reacts to.
Why B is correct: The rule routes the alarm state-change event directly to the runbook target, invoking the remediation event-driven with no polling and no custom code.
Why C is wrong: AWS Config evaluates resource configuration compliance, not CloudWatch metric thresholds, so it cannot detect a QueueAge breach and is the wrong detector here.
Why D is wrong: Run Command runs commands on managed nodes on demand, but scheduling it to poll the metric reintroduces the polling the team wants to avoid and is not event-driven.
Why E is wrong: A scheduled function is custom polling code on a timer, which adds maintenance and latency and contradicts the requirement for no polling and no bridging code.