CapacityReservation.yaml

AWSTemplateFormatVersion: '2010-09-09'
Description: 'CloudFormation template to create encrypted SNS topic with email subscription and EventBridge rule for EC2 Capacity Reservation state changes'

Parameters:
  EmailAddress:
    Type: String
    Description: 'Email address to subscribe to the SNS topic'
    AllowedPattern: '^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'
    ConstraintDescription: 'Must be a valid email address'
  
  CapacityReservationId:
    Type: String
    Description: 'ID of the EC2 Capacity Reservation to monitor (e.g., cr-1234567890abcdef0)'
    AllowedPattern: '^cr-[a-f0-9]{17}$'
    ConstraintDescription: 'Must be a valid Capacity Reservation ID starting with cr- followed by 17 hexadecimal characters'

  MonitoredStates:
    Type: String
    Description: 'Comma-separated list of Capacity Reservation states to monitor (e.g., failed,expired,cancelled,pending)'
    AllowedPattern: '^[a-z]+(,[a-z]+)*$'
    ConstraintDescription: 'Must be lowercase, comma-separated states without spaces (e.g., failed,expired,cancelled)'

Resources:
  MySnsTopic:
    Type: 'AWS::SNS::Topic'
    Properties:
      DisplayName: 'My Notification Topic'
      KmsMasterKeyId: 'alias/aws/sns'  # Uses AWS managed key for SNS
      Subscription:
        - Endpoint: !Ref EmailAddress
          Protocol: 'email'

  EC2StateChangeRule:
    Type: 'AWS::Events::Rule'
    Properties:
      Name: 'EC2CapacityReservationStateChange'
      Description: 'Rule to capture EC2 Capacity Reservation state changes'
      State: 'ENABLED'
      EventPattern:
        source:
          - aws.ec2
        detail-type:
          - 'EC2 Capacity Reservation State Change'
        detail:
          State: !Split [',', !Ref MonitoredStates]
          capacity-reservation-id:
            - !Ref CapacityReservationId
      Targets:
        - Arn: !Ref MySnsTopic
          Id: 'SendToSNS'

Outputs:
  TopicArn:
    Description: 'ARN of the created SNS Topic'
    Value: !Ref MySnsTopic
  RuleArn:
    Description: 'ARN of the created EventBridge Rule'
    Value: !GetAtt EC2StateChangeRule.Arn
  MonitoredCapacityReservationId:
    Description: 'Capacity Reservation ID being monitored'
    Value: !Ref CapacityReservationId
  MonitoredStatesOutput:
    Description: 'Capacity Reservation states being monitored'
    Value: !Ref MonitoredStates