DOP-C02 Practice Question 22: Pipeline Source Change Detection
AWS Certified DevOps Engineer – Professional (DOP-C02) · Test 3 · question 2 of 10
A team's release pipeline in AWS CodePipeline takes its input from a versioned Amazon S3 object that a build job uploads. Developers complain that after the object is uploaded it can take several minutes before the pipeline execution starts. The pipeline definition shows PollForSourceChanges set to true on the source action. The team wants executions to start as soon as a new object version is uploaded, with the least operational overhead.
What should the team do?
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Answer:
CodePipeline documents two ways a source change can start a pipeline. Polling (PollForSourceChanges) periodically checks the source, and the docs say plainly that this trigger type "is not recommended and should be migrated to use automated change detection." Event-based detection starts the execution from the change event itself, so the delay is effectively the event delivery time rather than the gap until the next poll. For an S3 source that means a CloudTrail trail capturing data events for the bucket or prefix plus an EventBridge rule targeting the pipeline, the setup the console creates for you when you pick the recommended detection method.
Option A assumes a tunable interval. PollForSourceChanges is a boolean: you cannot configure how often CodePipeline polls, so there is no knob to turn.
Option C replaces one poll with another, worse one. It starts an execution every minute whether or not anything changed, which floods the execution history, burns build minutes, and still averages 30 seconds of delay.
Option D changes how concurrent executions queue, not how a change is noticed. If the pipeline is idle when the object lands, the case being described, execution mode has no effect on the delay.
Reference: Start a pipeline in CodePipeline