Which solution will meet these requirements with the LEAST operational overhead?

Explanations:

Writing an AWS Lambda function to create an RDS snapshot every day adds unnecessary complexity and operational overhead. While it achieves the goal, it requires additional monitoring, management, and potential error handling that can be avoided.

Modifying the RDS database to have a retention period of 30 days for automated backups is the simplest solution. This approach uses RDS’s built-in functionality, which automatically manages backups without additional operational overhead. The daily automated backups will be retained for the required period.

Using AWS Systems Manager Maintenance Windows to modify the RDS backup retention period does not address the daily backup requirement. This option only focuses on changing the retention period without ensuring that backups are taken daily, and it adds unnecessary complexity to the management of backups.

Creating a manual snapshot every day using the AWS CLI meets the daily backup requirement, but it involves more operational overhead. It requires manual intervention or automation setup, which could lead to missed backups if not managed properly. This option is less efficient compared to leveraging RDS’s automated backup features.