Flash card
AWS Systems Manager State Manager: associations that hold managed instances at a defined configuration.
- An association binds a document to a set of targets and a schedule, and reapplies it so configuration converges rather than drifting.
- Targets are chosen by tag or resource group, so an instance launched later into the same tag is configured without anyone acting.
- Applies at an interval you set, which is what separates it from a one-off command.
- Compliance status per association shows which instances are in the desired state and which failed to converge.
- Rate control and error thresholds bound how fast an association rolls across a fleet.
Pick it when
Pick it over Run Command when the requirement is to keep something true rather than to do something once. Run Command executes now; State Manager keeps reapplying. Pick it over Patch Manager when the state is configuration generally, rather than patch baselines specifically.
It's the wrong answer when
It is the wrong answer for provisioning the infrastructure itself, which is CloudFormation, and for one-time remediation triggered by an event, which is Automation. It configures instances that already exist.