RDS instance is protected by an AWS Backup plan

# Assign an RDS instance to an AWS Backup plan
resource "aws_backup_selection" "<example_resource_name>" {
  name         = "<selection_name>"
  plan_id      = "<example_backup_plan_id>"   # CRITICAL: attaches to the backup plan
  iam_role_arn = "<example_role_arn>"         # CRITICAL: role AWS Backup uses
  resources    = ["<rds-instance-arn>"]       # CRITICAL: RDS instance protected by the plan
}

# CloudFormation: assign an RDS instance to an AWS Backup plan
Resources:
  <example_resource_name>:
    Type: AWS::Backup::BackupSelection
    Properties:
      BackupPlanId: <example_backup_plan_id>  # CRITICAL: targets the backup plan to protect the instance
      BackupSelection:
        SelectionName: <selection_name>
        IamRoleArn: <example_role_arn>        # CRITICAL: role AWS Backup uses to back up the resource
        Resources:
          - <rds-instance-arn>                # CRITICAL: assigns the RDS instance to the plan