Question

A CloudOps engineer uses AWS CloudFormation to launch a single EC2 instance that runs a lengthy application installation script via UserData. Currently CloudFormation marks the stack as CREATE_COMPLETE as soon as the instance launches, but before the application finishes installing, causing downstream resources to fail because the app is not yet ready. The engineer needs the stack to wait until the application setup completes successfully before reporting the resource as created. What is the MOST appropriate way to achieve this?

Accepted Answer

Add a CreationPolicy with a ResourceSignal timeout to the EC2 instance and call cfn-signal from the UserData script once installation succeeds

Answer

Add a DependsOn attribute referencing the EC2 instance to all downstream resources

Answer

Configure a DeletionPolicy of Retain on the EC2 instance so CloudFormation waits before completing

Answer

Enable termination protection on the stack and use drift detection to confirm the application is ready