Step 1: Understanding the Deletion FailureThe most likely reason why the CloudFormation stack failed to delete is that the S3 bucket was not empty. AWS CloudFormation cannot delete an S3 bucket that contains objects, so if the website files are still in the bucket, the deletion will fail.
Issue: The S3 bucket is not empty during deletion, preventing the stack from being deleted.
Step 2: Modifying the Custom Resource to Handle DeletionTo mitigate this issue, you can modify the Lambda function associated with the custom resource to automatically empty the S3 bucket when the stack is being deleted. By adding logic to handle the RequestType: Delete event, the function can recursively delete all objects in the bucket before allowing the stack to be deleted.
Action: Modify the Lambda function to recursively delete the objects in the S3 bucket when RequestType is set to Delete.
Why: This ensures that the S3 bucket is empty before CloudFormation tries to delete it, preventing the stack deletion failure.
Reference: AWS documentation on CloudFormation custom resources.
This corresponds to Option B: Deletion has failed because the S3 bucket is not empty. Modify the custom resource's AWS Lambda function code to recursively empty the bucket when RequestType is Delete.

AWS Health provides real-time events and information related to your AWS infrastructure. It can be integrated with Amazon EventBridge to act upon the health events automatically. If the maintenance notification from AWS Health indicates that an EC2 instance requires a restart, you can set up an EventBridge rule to respond to such events. In this case, the target of this rule would be a Lambda function that would trigger a Systems Manager automation to restart the EC2 instance during a maintenance window. Remember, AWS Health is the source of the events (not EC2 or Systems Manager), and AWS Lambda can be used to execute complex remediation tasks, such as scheduling maintenance tasks via Systems Manager.
The following are the steps involved in configuring the EventBridge rule to meet these requirements:
Configure an event source of AWS Health, a service of EC2, and an event type that indicates instance maintenance.
Target a newly created AWS Lambda function that registers an automation task to restart the EC2 instance during a maintenance window.
The AWS Lambda function will be triggered by the event from AWS Health. The function will then register an automation task to restart the EC2 instance during the next maintenance window.

ECR Lifecycle Policies automatically manage image retention based on tag status, age, or count. They execute natively within the ECR service, requiring no external management or scripts - the least overhead and AWS-recommended cleanup method.