feat(DBShardGroup) - RDS CloudFormation Aurora Limitless Support

[angusy29]

https://aws.amazon.com/blogs/aws/amazon-aurora-postgresql-limitless-database-is-now-generally-available/

Description of changes:

RDS CloudFormation now supports creation of Aurora Limitless DBShardGroups.

A new DBShardGroup resource has been introduced allowing you to scale beyond existing Aurora limits for write throughput and storage by distributing database workload over multiple Aurora writer instances while maintaining the ability to use it as a single database.

To begin using a DBShardGroup, you need a DBCluster with ClusterScalabilityType set to Limitless.

Example:

AWSTemplateFormatVersion: 2010-09-09
Description: IAM role, DBCluster, and DBInstance required for DBShardGroup creation

Resources:
  EnhancedMonitoringAccessRole:
    Type: AWS::IAM::Role
    DeletionPolicy: Delete
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: "Allow"
            Principal:
              Service:
                - "monitoring.rds.amazonaws.com"
            Action: "sts:AssumeRole"
      ManagedPolicyArns:
        - !Sub "arn:${AWS::Partition}:iam::aws:policy/service-role/AmazonRDSEnhancedMonitoringRole"
      PermissionsBoundary: !Sub "arn:${AWS::Partition}:iam::aws:policy/service-role/AmazonRDSEnhancedMonitoringRole"
  DBCluster:
    Type: AWS::RDS::DBCluster
    DeletionPolicy: Delete
    Properties:
      ClusterScalabilityType: "limitless"
      EnableCloudwatchLogsExports:
        - postgresql
      Engine: "aurora-postgresql"
      EngineVersion: "16.4-limitless"
      MasterUsername: "username"
      MasterUserPassword: "password"
      MonitoringInterval: 60
      MonitoringRoleArn: !GetAtt EnhancedMonitoringAccessRole.Arn
      Port: 5432
      PerformanceInsightsEnabled: "true"
      PerformanceInsightsRetentionPeriod: 31
      StorageType: "aurora-iopt1"
  DBShardGroup:
    Properties:
      ComputeRedundancy: '0'
      DBClusterIdentifier: !Ref DBCluster
      MaxACU: '32'
      MinACU: '16'
      PubliclyAccessible: 'False'
      Tags:
        - Key: created-with
          Value: created-value
    Type: AWS::RDS::DBShardGroup

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