AWSTemplateFormatVersion: 2010-09-09

Description: >-
  Creates an Aurora serverless MySQL database cluster. **WARNING** You will be
  billed for the AWS resources used if you create a stack from this template.

Metadata:
  LICENSE: Apache License Version 2.0
  cfn-lint:
    config:
      ignore_checks:
        # Check for QSID
        - E9008
        # Check for RDS Storage encryption enabled
        - ERDSStorageEncryptionEnabled
  AWS::CloudFormation::Interface:
    ParameterGroups:
      - Label:
          default: Database configuration
        Parameters:
          - DBName
          - DBUsername
          - DBPassword
          - DBMaxCapacity
          - DBMinCapacity
          - EnableDataAPI
          - DBBackupRetentionPeriod
          - DBPreferredBackupWindow
      - Label:
          default: Network configuration
        Parameters:
          - PrivateSubnet1AID
          - PrivateSubnet2AID
          - PrivateSubnet3AID
          - DBSecurityGroupId
    ParameterLabels:
      DBName:
        default: Database name
      DBBackupRetentionPeriod:
        default: Database backup retention period
      DBUsername:
        default: Username
      DBPassword:
        default: Password
      EnableDataAPI:
        default: Enable Data API
      PrivateSubnet1AID:
        default: Private subnet 1 ID
      PrivateSubnet2AID:
        default: Private subnet 2 ID
      PrivateSubnet3AID:
        default: Private subnet 3 ID
      DBSecurityGroupId:
        default: Database security group ID

Parameters:
  PrivateSubnet1AID:
    Type: 'AWS::EC2::Subnet::Id'
    Description: Subnet Id for private subnet 1 located in Availability Zone 1.
    AllowedPattern: '^subnet-[a-zA-Z0-9]*$'
    ConstraintDescription: Invalid subnet id
  PrivateSubnet2AID:
    Type: 'AWS::EC2::Subnet::Id'
    Description: Subnet Id for private subnet 2 located in Availability Zone 2.
    AllowedPattern: '^subnet-[a-zA-Z0-9]*$'
    ConstraintDescription: Invalid subnet id
  PrivateSubnet3AID:
    Type: String
    Description: Subnet Id for private subnet 3 located in Availability Zone 3.
    Default: ''
  DBName:
    Type: String
    Description: The name of your database. Must be unique. If you don't provide a name, then Amazon RDS won't create a database in this DB cluster.
    AllowedPattern: '[a-zA-Z][a-zA-Z0-9]*'
    MaxLength: '64'
    MinLength: '5'
  DBUsername:
    NoEcho: 'true'
    Description: Username for MySQL database access.
    Type: String
    MinLength: '1'
    MaxLength: '16'
    AllowedPattern: '[a-zA-Z][a-zA-Z0-9]*'
    ConstraintDescription: must begin with a letter and contain only alphanumeric characters.
  DBPassword:
    NoEcho: 'true'
    Description: Password MySQL database access.
    Type: String
    MinLength: '8'
    MaxLength: '41'
    AllowedPattern: '[a-zA-Z0-9]*'
    ConstraintDescription: must contain only alphanumeric characters.
  DBBackupRetentionPeriod:
    Type: Number
    Default: '1'
    Description: The number of days for which automated backups are retained.
    ConstraintDescription: Database backup retention period must be between 1 and 35 days.
    MaxValue: '35'
    MinValue: '1'
  DBMaxCapacity:
    Type: Number
    Default: '2'
    Description: The maximum capacity for an Aurora DB cluster in serverless DB engine mode.
    AllowedValues: ['1', '2', '4', '8', '16', '32', '64', '128', '256']
  DBMinCapacity:
    Type: Number
    Default: '1'
    Description: The minimum capacity for an Aurora DB cluster in serverless DB engine mode.
    AllowedValues: ['1', '2', '4', '8', '16', '32', '64', '128', '256']
  DBPreferredBackupWindow:
    Type: String
    Default: ''
    Description: (Optional) The daily time range during which automated backups are created.
    AllowedPattern: '^(|([0-1][0-9]|2[0-3]):[0-5][0-9]-([0-1][0-9]|2[0-3]):[0-5][0-9])$'
    ConstraintDescription: 'Preferred backup window must be left blank or in the form of HH:MM-HH:MM'
  DBSecurityGroupId:
    Type: 'AWS::EC2::SecurityGroup::Id'
    Description: The group ID of the database security group, such as sg-94b3a1f6.
    AllowedPattern: '^sg-[a-zA-Z0-9]*$'
    ConstraintDescription: Please select DBSecurityGroupId security group.
  EnableDataAPI:
    Type: String
    Description: >-
      When enabled, the HTTP endpoint provides a connectionless web service API for running SQL queries on the Aurora Serverless DB cluster. 
      You can also query your database from inside the RDS console with the query editor.
    Default: 'true'
    AllowedValues:
      - 'true'
      - 'false'

Conditions:
  3AZDeployment: !Not 
    - !Equals 
      - !Ref PrivateSubnet3AID
      - ''

Resources:
  DBSubnetGroup:
    Type: 'AWS::RDS::DBSubnetGroup'
    Properties:
      DBSubnetGroupDescription: Subnets available for the cluster
      SubnetIds: !If 
        - 3AZDeployment
        - - !Ref PrivateSubnet1AID
          - !Ref PrivateSubnet2AID
          - !Ref PrivateSubnet3AID
        - - !Ref PrivateSubnet1AID
          - !Ref PrivateSubnet2AID
      Tags:
        - Key: Name
          Value: !Join 
            - ''
            - - !Ref DBName
              - SubnetGroup
  DBCluster:
    Type: 'AWS::RDS::DBCluster'
    DeletionPolicy: Delete
    Properties:
      Engine: aurora-mysql
      EngineVersion: '5.7'
      EngineMode: serverless
      StorageEncrypted: 'true'
      DatabaseName: !Ref DBName # should be unique
      DBClusterIdentifier: !Join 
        - ''
        - - !Ref DBName
          - Cluster
      DBSubnetGroupName: !Ref DBSubnetGroup
      MasterUsername: !Ref DBUsername
      VpcSecurityGroupIds:
        - !Ref DBSecurityGroupId
      MasterUserPassword: !Ref DBPassword
      EnableHttpEndpoint: !Ref EnableDataAPI
      BackupRetentionPeriod: !Ref DBBackupRetentionPeriod
      PreferredBackupWindow: !Ref DBPreferredBackupWindow
      ScalingConfiguration:
        AutoPause: 'true'
        SecondsUntilAutoPause: 300
        MaxCapacity: !Ref DBMaxCapacity
        MinCapacity: !Ref DBMinCapacity

Outputs:
  DBEndpoint:
    Description: The connection endpoint of your database.
    Value: !Join 
      - ''
      - - !GetAtt DBCluster.Endpoint.Address
        - ':'
        - !GetAtt DBCluster.Endpoint.Port
        - /
        - !Ref DBName
  DBName:
    Description: The name of your database.
    Value: !Ref DBName