AWS Certified Cloud Practitioner (CLF-C02)Cloud Technology and ServicesHard
A company wants to deploy a new application version by gradually replacing instances running the old version with instances running the new version, a few at a time, until all instances are updated. If a problem is detected midway, only a portion of traffic is affected. Which deployment method does this describe?
- ARolling deployment
- BBlue/Green deployment
- CAll-at-once deployment
- DCanary deployment
Show answer & explanationAnswer & explanation
Correct answer: A. Rolling deployment
A rolling deployment incrementally replaces instances of the old version with the new version in batches, rather than switching all traffic at once or maintaining two fully separate environments; this limits the blast radius if issues arise but does not provide an instant full rollback like blue/green.
Why the other options are wrong
- B. Blue/Green deployment maintains two complete separate environments and shifts all traffic at once (or via routing rules), not a gradual instance-by-instance replacement.
- C. All-at-once deployment updates every instance simultaneously, causing downtime and full exposure to any new-version issues.
- D. Canary deployment releases the new version to a small, fixed percentage of users first before a broader release, rather than incrementally replacing all instances in batches.
Rolling Deployment
A deployment strategy that gradually replaces instances running the old application version with instances running the new version, in batches, until fully updated.
- Reduces risk by limiting exposure to a subset of instances at a time
- No need for duplicate full-scale environment like blue/green
- Rollback can be slower than blue/green since old instances are already replaced
Memory trick: Rolling deployment: swap instances one batch at a time, like changing tires while driving slowly.