Posted On: Mar 24, 2022
Amazon EC2 Auto Scaling now publishes Auto Scaling instance lifecycle states in the Amazon EC2 Instance Metadata Service (IMDS), enabling you to easily initiate on-instance actions as an instance transitions from one lifecycle state to another. Instances in an Auto Scaling group transition through various lifecycle states from the time they are launched and placed in service to when they are removed from service and terminated. By polling IMDS, you can setup your on-instance application to easily determine its lifecycle state without having to setup Amazon CloudWatch Events or other services.
For example, you may want to run additional initialization steps on your instance when it is transitioning between lifecycle states, such as downloading and installing software after instance launch. To do this, you can have your application perform the necessary action when it sees the appropriate state in IMDS, and use Amazon EC2 Auto Scaling Lifecycle hooks to wait for your initialization steps to complete before moving to the next lifecycle state.