When an instance is locked, it remains protected from standard scale-down activities and Fix Strategy actions. 

However, this protection does not apply to unhealthy instances. If an instance becomes unhealthy, the auto-healing mechanism initiates the replacement process, which attempts to detach the unhealthy instance. The detach command does not consider instance protection, so locked instances will still be terminated and replaced to maintain the health of your Elastigroup.

For additional details on locking instances and their behavior, see Lock an instance.

Outcome

Instances marked as locked are not immune to auto-healing. They will be replaced if they become unhealthy, ensuring the group remains stable and functional.