fix(docdb): cannot delete a stack with DatabaseCluster removal_policy set to 'Retain'

[jadamariano]

Issue #29054

Closes #29054

Reason for this change

After creating a DocumentDB DatabaseCluster with a removal_policy set to Retain, the CloudFormation stack can not be deleted. The stack can not be deleted because the associated subnet group can not be removed if it points to an existing cluster.

Sample error from CloudFormation:
Got InvalidDBInstanceStateException with error: Cannot delete the subnet group '{subnet_group_name}' because at least one database instance: {instance_name} is still using it.

This same bug was happening for the aws-rds DatabaseCluster (#5282), until this fix came around. I suggest to make the same fix for the aws-docdb DatabaseCluster, where it sets the retention policy of DbSubnetGroup to 'Retain' if it is 'Retain' on the DatabaseCluster.

Description of changes

1. Updated packages/aws-cdk-lib/aws-docdb/lib/cluster.ts to set the retention policy of DbSubnetGroup to 'Retain' if it is 'Retain' on the DatabaseCluster.

if (props.removalPolicy === RemovalPolicy.RETAIN) {
  subnetGroup.applyRemovalPolicy(RemovalPolicy.RETAIN);
}

2. Added test case in packages/aws-cdk-lib/aws-docdb/test/cluster.test.ts for the scenario where the retention policy of DbSubnetGroup should be 'Retain' if it is 'Retain' on the DatabaseCluster.

Description of how you validated changes

Added test case in packages/aws-cdk-lib/aws-docdb/test/cluster.test.ts for the scenario where the retention policy of DbSubnetGroup should be 'Retain' if it is 'Retain' on the DatabaseCluster.

Also ran the integration tests for aws-docdb by using the command yarn integ --directory test/aws-docdb/test.

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[aws-cdk-automation]

The pull request linter has failed. See the aws-cdk-automation comment below for failure reasons. If you believe this pull request should receive an exemption, please comment and provide a justification.

A comment requesting an exemption should contain the text Exemption Request. Additionally, if clarification is needed add Clarification Request to a comment.

✅ Updated pull request passes all PRLinter validations. Dismissing previous PRLinter review.

[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: 4115a68
• Result: FAILED
• Build Logs (available for 30 days)

Powered by github-codebuild-logs, available on the AWS Serverless Application Repository

[aws-cdk-automation]

This PR has been in the BUILD FAILING state for 3 weeks, and looks abandoned. To keep this PR from being closed, please continue work on it. If not, it will automatically be closed in a week.

[aws-cdk-automation]

This PR has been deemed to be abandoned, and will be automatically closed. Please create a new PR for these changes if you think this decision has been made in error.