An existing Lambda deployment must expose a new version to a small traffic percentage, observe errors, and revert automatically if thresholds breach. Which release design best fits?

1. Delete the prior version immediately after deployment begins.
2. Run only a syntax check and disable runtime alarms.
3. Update $LATEST in place and route every client to it before collecting metrics.
4. Use a supported canary configuration with alias traffic shifting, alarms, and automatic rollback.