Question

A SysOps administrator is authoring a CloudFormation template that provisions EC2 instances running a web application. The instances must install packages, write configuration files, and start services in a specific, ordered sequence during launch. The administrator also wants the CloudFormation stack to wait until the bootstrap process completes successfully before marking the resource CREATE_COMPLETE, and to report a failure if the configuration does not finish. Which approach best meets these requirements?

Accepted Answer

Define the bootstrap steps in the AWS::CloudFormation::Init metadata, invoke cfn-init in the instance UserData, and use cfn-signal with a CreationPolicy on the instance to report success or failure.

Answer

Place all install and configuration commands as a shell script in UserData, and rely on the EC2 instance reaching the 'running' state to signal completion to CloudFormation.

Answer

Use a DependsOn attribute on the EC2 instance referencing a WaitConditionHandle so CloudFormation automatically pauses until packages are installed.

Answer

Configure the bootstrap steps in an SSM State Manager association and set a DeletionPolicy of Retain on the instance to ensure configuration completes.