PAS-C01 Technology Practice Question

Correct answer & explanation

AWS CloudFormation's CreationPolicy with cfn-signal allows you to control the stack creation process by waiting for a signal from the EC2 instance after it has completed its configuration. When using a CreationPolicy, CloudFormation will not mark the resource as created until it receives a signal (e.g., via cfn-signal) indicating that the installation script has finished. This is ideal for automating SAP HANA installations where you need to ensure the software is fully installed before proceeding. Option A is incorrect because AWS::CloudFormation::Init (cfn-init) is used to install packages, create files, and run commands during instance launch, but it does not provide a mechanism for CloudFormation to wait for the completion of long-running scripts; it runs as part of the user data and returns immediately. Option C is incorrect because while a Lambda function can be triggered by EC2 state changes, it does not integrate directly with CloudFormation's stack creation process to signal completion. You would need additional custom logic to send a signal back to CloudFormation, making it less straightforward than using CreationPolicy. Option D is incorrect because EC2 User Data runs once at instance launch, but CloudFormation does not inherently wait for user data scripts to finish. Without a CreationPolicy or similar mechanism, CloudFormation will proceed to the next resource immediately after launching the instance, even if the script is still running.