---
AWSTemplateFormatVersion: 2010-09-09

Parameters:

  AlarmThreshold:
    Description: Set a threshold for the alarm to go off if the estimated charge is exceeded. 
    Type: Number
    MinValue: 1
    MaxValue: 10000000

  Email:
    Description: Email address to notify if the threshold is breached. You should get a confirmation email from SNS once the resources are created.
    Type: String
    AllowedPattern: ^[_A-Za-z0-9-\+]+(\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\.[A-Za-z0-9]+)*(\.[A-Za-z]{2,})$

Resources:

  BillingAlarm:
    Type: AWS::CloudWatch::Alarm
    Properties:
      AlarmDescription: !Sub Alarm if AWS spending is over $${AlarmThreshold}
      Namespace: AWS/Billing
      MetricName: EstimatedCharges
      Dimensions:
      - Name: Currency
        Value: USD
      Statistic: Maximum
      Period: 21600
      EvaluationPeriods: 1
      Threshold: !Ref AlarmThreshold
      ComparisonOperator: GreaterThanThreshold
      AlarmActions:
      - !Ref BillingAlarmTopic

  BillingAlarmTopic:
    Type: AWS::SNS::Topic
    Properties:
      Subscription:
      - Endpoint: !Ref Email
        Protocol: email

Outputs:

  BillingAlarmTopicArn:
    Description: Billing Alarm Topic ARN
    Value: !Ref BillingAlarmTopic
    Export:
      Name: !Sub ${AWS::StackName}-BillingAlarmTopicArn

  BillingAlarmTopicName:
    Description: Billing Alarm Topic Name
    Value: !GetAtt BillingAlarmTopic.TopicName
    Export:
        Name: !Sub ${AWS::StackName}-BillingAlarmTopicName