CloudFormation DeletionPolicy: Retain S3 Buckets When Stack Is Deleted

Exhibit

Refer to the exhibit.

Resources:
  MyBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Sub "${AWS::StackName}-mybucket-${AWS::Region}"
      VersioningConfiguration:
        Status: Enabled
    DeletionPolicy: Retain

A DevOps engineer deploys the CloudFormation snippet shown in the exhibit. After the stack is deleted, the engineer checks for the S3 bucket. Which statement best describes the outcome?

⚠ Common exam trap

It's easy for candidates to assume stack deletion always removes all resources, overlooking that the DeletionPolicy attribute can explicitly override that behavior for supported resource types like S3 buckets.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

The bucket is retained (not deleted) after the stack deletion.

S3 bucket versioning has no bearing on this stack's deletion mechanics since the bucket uses DeletionPolicy: Retain, so CloudFormation never attempts to delete the physical bucket. More generally, versioning is a bucket-level data-protection feature; it does not, by itself, cause a CloudFormation stack deletion to fail. However, note that CloudFormation does NOT automatically empty a bucket's object versions and delete markers before deleting it -- if DeletionPolicy were Delete (the default) and the bucket were non-empty (including having any object versions), the stack deletion would fail with a 'bucket not empty' error, requiring a custom resource or manual emptying first. Because this stack uses Retain, the deletion action is never attempted, so the bucket -- and any versioned objects in it -- persists after the stack is deleted.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
The bucket is deleted because the stack deletion overrides the DeletionPolicy.
Why it's wrong here
This statement reverses the actual precedence. CloudFormation's DeletionPolicy attribute is evaluated as part of the stack deletion operation and is the final authority on whether a physical resource is removed; a plain stack deletion cannot override it. With 'Retain' set, CloudFormation deliberately skips the bucket deletion, so the bucket is preserved despite the stack being successfully deleted.
✓
The bucket is retained (not deleted) after the stack deletion.
Why this is correct
When a CloudFormation stack that contains an AWS::S3::Bucket with DeletionPolicy: Retain is deleted, the template's deletion intent is to leave that bucket in place. The bucket, including any objects and versions, remains in your AWS account and is no longer under CloudFormation's management. The stack itself shows DELETE_COMPLETE because CloudFormation treats the Retain policy as a successful completion of the resource deletion step, even though no physical deletion occurred.
✗
The stack deletion fails because the bucket has versioning enabled.
Why it's wrong here
S3 bucket versioning has no bearing on CloudFormation stack deletion mechanics. Versioning is a bucket-level data-protection feature; it does not lock the bucket against deletion of the bucket itself, nor does it cause CloudFormation to fail a stack deletion. In the absence of a Retain policy, CloudFormation can delete a versioned bucket by purging all object versions and delete markers before issuing the DELETE_BUCKET call. More importantly, because this stack uses Retain, the deletion action is never attempted, so versioning cannot trigger a failure.
✗
The bucket is deleted along with the stack because the DeletionPolicy is not supported for S3 buckets.
Why it's wrong here
This claim is factually incorrect because DeletionPolicy is explicitly supported for AWS::S3::Bucket and is widely used for exactly this purpose. The CloudFormation documentation lists S3::Bucket as a resource that supports the Retain value, and the default (no policy) is Delete. Defining 'DeletionPolicy: Retain' on the bucket is the standard way to prevent data loss when a stack is removed; therefore the bucket is preserved, not deleted.

Quick reference

AWS S3 Storage Class Comparison

Storage Class	Min Duration	Retrieval	Use Case
S3 Standard	None	Immediate	Frequently accessed data
S3 Standard-IA	30 days	Immediate	Infrequent access, rapid retrieval
S3 One Zone-IA	30 days	Immediate	Non-critical infrequent data
S3 Intelligent-Tiering	None	Immediate–hours	Unknown or changing access patterns
S3 Glacier Instant	90 days	Milliseconds	Archive with instant retrieval
S3 Glacier Flexible	90 days	Minutes–hours	Archive, flexible retrieval
S3 Glacier Deep Archive	180 days	Hours	Long-term compliance archive

Go deeper

CloudFormation DeletionPolicy: Retain S3 Buckets When Stack Is Deleted

Exhibit

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

Related to this question