A fleet of EC2 instances must keep a specific configuration, such as the CloudWatch agent installed and running. If someone changes it by hand, the desired configuration should be reapplied automatically on a schedule. Which Systems Manager capability does this?
Show answer and explanation
Answer: A
State Manager associations apply a Systems Manager document to targeted managed instances, either once or on a repeating schedule. Running the association periodically reapplies the desired state, so manual drift is corrected on the next run. It is the native tool for continuous configuration enforcement on managed instances.
Why the other options are wrong
- B. Run Command runs once when you invoke it and does not reapply the desired state later on its own.
- C. Inventory records what software and configuration exist on instances, but it does not correct drift.
- D. A Maintenance Window schedules tasks against targets. With no targets or tasks, it does nothing at all.