db.yml

---
AWSTemplateFormatVersion: 2010-09-09

Description: RDS

# Database stack creation prerequisite:  First create a VPC stack - see README for more info
Parameters:

  NetworkStackName:
    Description: Name of an active CloudFormation stack that contains networking resources
    Type: String
    MinLength: 1
    MaxLength: 255
    AllowedPattern: "^[a-zA-Z][-a-zA-Z0-9]*$"

  DatabaseUser:
    Default: startupadmin
    Type: String
    Description: Database admin account name
    MinLength: 5
    MaxLength: 16
    AllowedPattern: "[a-zA-Z][a-zA-Z0-9]*"
    ConstraintDescription: Name must begin with a letter and contain only alphanumeric characters

  DatabasePassword:
    NoEcho: true
    Type: String
    Description: Database admin account password
    MinLength: 6
    MaxLength: 41
    AllowedPattern: "[a-zA-Z0-9]*"
    ConstraintDescription: Password must contain only alphanumeric characters

  DatabaseName:
    Default: StartupDB
    Type: String
    Description: Database name
    MinLength: 1
    MaxLength: 30
    AllowedPattern: "[a-zA-Z][a-zA-Z0-9]*"
    ConstraintDescription: Name must begin with a letter and contain only alphanumeric characters

  DatabaseSize:
    Default: 5
    Type: Number
    Description: Database storage size in gigabytes (GB)
    MinValue: 5
    ConstraintDescription: Enter a size of at least 5 GB

  # Default is 500 MB
  DatabaseAlarmMinFreeSpaceInBytes:
    Default: 524288000
    Type: Number
    Description: Number of min free space bytes for alarm (if enabled)
    MinValue: 1
    ConstraintDescription: A value of one byte or more

  # Default is 200 MB
  DatabaseAlarmSwapUsageInBytes:
    Default: 209715200
    Type: Number
    Description: Number of swap usage bytes for alarm (if enabled)
    MinValue: 1
    ConstraintDescription: A value of one byte or more

  DatabaseEngine:
    Default: postgres
    Type: String
    Description: Database engines - PostgreSQL, MariaDB or MySQL
    ConstraintDescription: Choose an engine from the drop down
    AllowedValues:
      - postgres
      - mariadb
      - mysql

  EncryptionAtRest:
    Default: false
    Type: String
    Description: The optional flag for encryption at rest (db.t2.small and above)
    ConstraintDescription: Only true or false are allowed
    AllowedValues:
      - true
      - false

  DatabaseInstanceClass:
    Default: db.t2.micro
    Type: String
    Description: "Database instance class, e.g. db.t2.micro (free tier) - Engine support: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts.DBInstanceClass.html"
    ConstraintDescription: DB instance class not supported
    AllowedValues:
      - db.t2.micro
      - db.t2.small
      - db.t2.medium
      - db.t2.large
      - db.t2.xlarge
      - db.t2.2xlarge
      - db.m4.large
      - db.m4.xlarge
      - db.m4.2xlarge
      - db.m4.4xlarge
      - db.m4.10xlarge
      - db.m4.16xlarge
      - db.r4.large
      - db.r4.xlarge
      - db.r4.2xlarge
      - db.r4.4xlarge
      - db.r4.8xlarge
      - db.r4.16xlarge

  EnvironmentName:
    Description: Environment name, either dev or prod
    Type: String
    Default: dev
    AllowedValues:
      - dev
      - prod
    ConstraintDescription: Specify either dev or prod

  DatabaseAlarmMaxCpuPercent:
    Description: Database CPU % max for alarm
    Type: Number
    Default: 80
    MinValue: 1
    MaxValue: 99
    ConstraintDescription: Must be a percentage between 1-99%

  DatabaseAlarmReadLatencyMaxSeconds:
    Description: Read latency max for alarm
    Type: Number
    Default: 1
    MinValue: 1

  DatabaseAlarmWriteLatencyMaxSeconds:
    Description: Write latency max for alarm
    Type: Number
    Default: 1
    MinValue: 1

  DatabaseAlarmEvaluationPeriods:
    Description: The number of periods over which data is compared to the specified threshold
    Type: Number
    Default: 2
    MinValue: 2

  DatabaseAlarmEvaluationPeriodSeconds:
    Description: The time over which the specified statistic is applied. Specify time in seconds, in multiples of 60. Enhanced monitoring must be enabled if less than 500 seconds
    Type: Number
    Default: 300
    MinValue: 60
    ConstraintDescription: Must be at least 60 seconds

  EnhancedMonitoring:
    Default: false
    Type: String
    Description: The optional flag for enhanced monitoring (additional charges apply - https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_Monitoring.OS.html)
    ConstraintDescription: Only true or false are allowed
    AllowedValues:
      - true
      - false

  EnableAlarms:
    Default: false
    Type: String
    Description: Set to true to enable (additional charges - https://aws.amazon.com/cloudwatch/pricing/)
    ConstraintDescription: Only true or false are allowed
    AllowedValues:
      - true
      - false


Conditions:

  IsProd: !Equals [ !Ref EnvironmentName, prod ]

  AlarmsEnabled: !Equals [ !Ref EnableAlarms, true ]

  EnhancedMonitoringSupprtedAndEnabled: !And
    - !Condition AlarmsEnabled
    - !Equals [ !Ref EnhancedMonitoring, true ]
    - !Not [ !Equals [ !Ref DatabaseInstanceClass, "db.m1.small" ] ]


Resources:

  EnhancedMonitoringRole:
    Type: AWS::IAM::Role
    Condition: EnhancedMonitoringSupprtedAndEnabled
    Properties:
      Path: /
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
          - Effect: Allow
            Principal:
              Service: monitoring.rds.amazonaws.com
            Action: sts:AssumeRole
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AmazonRDSEnhancedMonitoringRole

  DatabaseAlarmTopic:
    Type: AWS::SNS::Topic
    Condition: AlarmsEnabled
    Properties:
      DisplayName: Database Alarm Topic

  DatabaseSubnetGroup:
    Type: AWS::RDS::DBSubnetGroup
    Properties:
      DBSubnetGroupDescription: Database subnet group
      SubnetIds:
        - Fn::ImportValue: !Sub ${NetworkStackName}-PrivateSubnet1ID
        - Fn::ImportValue: !Sub ${NetworkStackName}-PrivateSubnet2ID
      Tags:
        - Key: Name
          Value: !Ref AWS::StackName

  Database:
    Type: AWS::RDS::DBInstance
    Properties:
      DBSubnetGroupName: !Ref DatabaseSubnetGroup
      VPCSecurityGroups:
        - Fn::ImportValue: !Sub ${NetworkStackName}-DatabaseGroupID
      Engine: !Ref DatabaseEngine
      DBName: !Ref DatabaseName
      MasterUsername: !Ref DatabaseUser
      MasterUserPassword: !Ref DatabasePassword
      DBInstanceClass: !Ref DatabaseInstanceClass
      AllocatedStorage: !Ref DatabaseSize
      StorageType: gp2
      MultiAZ: !If [ IsProd, true, false ]
      StorageEncrypted: !Ref EncryptionAtRest
      MonitoringInterval: !If [ EnhancedMonitoringSupprtedAndEnabled, 60, 0 ]
      MonitoringRoleArn: !If [ EnhancedMonitoringSupprtedAndEnabled, !GetAtt EnhancedMonitoringRole.Arn, !Ref "AWS::NoValue" ]
      CopyTagsToSnapshot: true
      Tags:
        - Key: Name
          Value: !Ref AWS::StackName
    DependsOn: DatabaseSubnetGroup

  DatabaseCpuAlarm:
    Type: AWS::CloudWatch::Alarm
    Condition: AlarmsEnabled
    Properties:
      AlarmDescription: !Sub DB CPU utilization is over ${DatabaseAlarmMaxCpuPercent}% for ${DatabaseAlarmEvaluationPeriods} period(s) of ${DatabaseAlarmEvaluationPeriodSeconds} seconds
      TreatMissingData: notBreaching
      Namespace: AWS/RDS
      MetricName: CPUUtilization
      Unit: Percent
      Statistic: Average
      EvaluationPeriods: !Ref DatabaseAlarmEvaluationPeriods
      Period: !Ref DatabaseAlarmEvaluationPeriodSeconds
      Threshold: !Ref DatabaseAlarmMaxCpuPercent
      ComparisonOperator: GreaterThanOrEqualToThreshold
      Dimensions:
        - Name: DBInstanceIdentifier
          Value: !Ref Database
      AlarmActions:
        - !Ref DatabaseAlarmTopic
    DependsOn: Database

  DatabaseFreeStorageSpaceAlarm:
    Type: AWS::CloudWatch::Alarm
    Condition: AlarmsEnabled
    Properties:
      AlarmDescription: !Sub DB free storage space is less than ${DatabaseAlarmMinFreeSpaceInBytes} for ${DatabaseAlarmEvaluationPeriods} period(s) of ${DatabaseAlarmEvaluationPeriodSeconds} seconds
      TreatMissingData: notBreaching
      Namespace: AWS/RDS
      MetricName: FreeStorageSpace
      Unit: Bytes
      Statistic: Average
      EvaluationPeriods: !Ref DatabaseAlarmEvaluationPeriods
      Period: !Ref DatabaseAlarmEvaluationPeriodSeconds
      Threshold: !Ref DatabaseAlarmMinFreeSpaceInBytes
      ComparisonOperator: LessThanOrEqualToThreshold
      Dimensions:
        - Name: DBInstanceIdentifier
          Value: !Ref Database
      AlarmActions:
        - !Ref DatabaseAlarmTopic
    DependsOn: Database

  DatabaseSwapUsageAlarm:
    Type: AWS::CloudWatch::Alarm
    Condition: AlarmsEnabled
    Properties:
      AlarmDescription: !Sub DB swap usage is greater than than ${DatabaseAlarmSwapUsageInBytes} for ${DatabaseAlarmEvaluationPeriods} period(s) of ${DatabaseAlarmEvaluationPeriodSeconds} seconds
      TreatMissingData: notBreaching
      Namespace: AWS/RDS
      MetricName: SwapUsage
      Unit: Bytes
      Statistic: Average
      EvaluationPeriods: !Ref DatabaseAlarmEvaluationPeriods
      Period: !Ref DatabaseAlarmEvaluationPeriodSeconds
      Threshold: !Ref DatabaseAlarmSwapUsageInBytes
      ComparisonOperator: GreaterThanOrEqualToThreshold
      Dimensions:
        - Name: DBInstanceIdentifier
          Value: !Ref Database
      AlarmActions:
        - !Ref DatabaseAlarmTopic
    DependsOn: Database

  DatabaseReadLatencyAlarm:
    Type: AWS::CloudWatch::Alarm
    Condition: AlarmsEnabled
    Properties:
      AlarmDescription: !Sub DB read latency is over ${DatabaseAlarmReadLatencyMaxSeconds} for ${DatabaseAlarmEvaluationPeriods} period(s) of ${DatabaseAlarmEvaluationPeriodSeconds} seconds
      TreatMissingData: notBreaching
      Namespace: AWS/RDS
      MetricName: ReadLatency
      Unit: Seconds
      Statistic: Average
      EvaluationPeriods: !Ref DatabaseAlarmEvaluationPeriods
      Period: !Ref DatabaseAlarmEvaluationPeriodSeconds
      Threshold: !Ref DatabaseAlarmReadLatencyMaxSeconds
      ComparisonOperator: GreaterThanOrEqualToThreshold
      Dimensions:
        - Name: DBInstanceIdentifier
          Value: !Ref Database
      AlarmActions:
        - !Ref DatabaseAlarmTopic
    DependsOn: Database

  DatabaseWriteLatencyAlarm:
    Type: AWS::CloudWatch::Alarm
    Condition: AlarmsEnabled
    Properties:
      AlarmDescription: !Sub DB write latency is over ${DatabaseAlarmWriteLatencyMaxSeconds} for ${DatabaseAlarmEvaluationPeriods} period(s) of ${DatabaseAlarmEvaluationPeriodSeconds} seconds
      TreatMissingData: notBreaching
      Namespace: AWS/RDS
      MetricName: WriteLatency
      Unit: Seconds
      Statistic: Average
      EvaluationPeriods: !Ref DatabaseAlarmEvaluationPeriods
      Period: !Ref DatabaseAlarmEvaluationPeriodSeconds
      Threshold: !Ref DatabaseAlarmWriteLatencyMaxSeconds
      ComparisonOperator: GreaterThanOrEqualToThreshold
      Dimensions:
        - Name: DBInstanceIdentifier
          Value: !Ref Database
      AlarmActions:
        - !Ref DatabaseAlarmTopic
    DependsOn: Database


Outputs:

  Name:
    Description: RDS Stack Name
    Value: !Ref AWS::StackName
    Export:
      Name: !Sub ${AWS::StackName}-Name

  RdsDbId:
    Description: RDS Database ID
    Value: !Ref Database
    Export:
      Name: !Sub ${AWS::StackName}-DatabaseID

  RdsDbURL:
    Description: RDS Database URL
    Value: !GetAtt Database.Endpoint.Address
    Export:
      Name: !Sub ${AWS::StackName}-DatabaseURL

  DbUser:
    Description: RDS Database admin account user
    Value: !Ref DatabaseUser
    Export:
      Name: !Sub ${AWS::StackName}-DatabaseUser

  DbPassword:
    Description: RDS Database admin account password
    Value: !Ref DatabasePassword
    Export:
      Name: !Sub ${AWS::StackName}-DatabasePassword

  DatabaseAlarmTopicArn:
    Description: Database Alarm Topic ARN
    Condition: AlarmsEnabled
    Value: !Ref DatabaseAlarmTopic
    Export:
      Name: !Sub ${AWS::StackName}-DatabaseAlarmTopicArn

  DatabaseAlarmTopicName:
    Description: Database Alarm Topic Name
    Condition: AlarmsEnabled
    Value: !GetAtt DatabaseAlarmTopic.TopicName
    Export:
      Name: !Sub ${AWS::StackName}-DatabaseAlarmTopicName