AWSTemplateFormatVersion: 2010-09-09
Description: Alerting mechanism for monitoring resources.

Metadata:
  AWS::CloudFormation::Interface:
    ParameterGroups:
      - 
        Label: 
          default: SNS Topic information for whether you will create a new SNS Topic or use an existing one.
        Parameters:
          - pExistingOrCreateSNS
          - pExistingSNSID
          - pSNSTopicFriendlyName
          - pSNSEmail
      - 
        Label:
          default: Please enter information on the resource that will be monitored
        Parameters:
          - pUniqueResourceName
      - 
        Label:
          default: Define the attributes the alarm will use.
        Parameters:
          - pMetric
          - pThreshold
          - pPeriodLength
          - pEvaluationPeriods
          - pMissingData
          - pNamespace
          - pDimension
          - pStatistic
          - pComparisonOperator

    ParameterLabels:
      pExistingOrCreateSNS:
        default: "Will you be creating a new SNS Topic or using an existing SNS Topic?"
      pExistingSNSID:
        default: "Unique Resource Name of existing SNS Topic, if needed."
      pSNSTopicFriendlyName:
        default: "Name to give to the new SNS Topic, if you are creating one with this template."
      pSNSEmail:
        default: "For a NEW SNS Topic, please enter an email address for the alerts to be sent to."
      pUniqueResourceName:
        default: "Unique Resource Name of the resource to be monitored."
      pThreshold:
        default: Threshold to be assigned to the Alarm.
      pPeriodLength:
        default: Period length
      pEvaluationPeriods:
        default: Number of evaluation periods
      pMissingData:
        default: Missing Data.
      pNamespace:
        default: Namespace
      pDimension:
        default: Dimension
      pStatistic:
        default: Statistic
      pMetric:
        default: Metric
      pComparisonOperator:
        default: Comparison Operator

Parameters:
  pExistingOrCreateSNS:
    Type: String
    AllowedValues:
      - Create
      - Existing
    Description: Please select Create or Existing as appropriate from the options. 
    Default: Existing
  pSNSTopicFriendlyName:
    Type: String
    Default: None
    Description: If you need a new SNS topic created, please enter the friendly name you would like to give to that topic.
  pSNSEmail:
    Type: String
    AllowedPattern: ([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)
    ConstraintDescription: Must be a valid email address.
    Description: If you are creating a new SNS Topic, please enter a valid email or distribution group to send the alert too.
  pExistingSNSID:
    Type: String
    Default: None
    Description: Enter the Unique resource name of the SNS topic if you are using an existing one. Otherwise, leave the default of 'None'
  pUniqueResourceName:
    Type: String
    Description: Please provide the unique resource name of the resource being monitored.
    Default: Unique Resource Name
  pThreshold:
    Type: Number
    Description: Please enter the threshold for this alarm.
    Default: 0
  pPeriodLength:
    Type: Number 
    Description: The number of seconds the evaluation period should last. must be at least 60 seconds.
    Default: 60
  pEvaluationPeriods: 
    Type: Number
    Description: How many periods should be evaluated?
    Default: 1
  pMissingData:
    Description: How would you like to treat missing data?
    Type: String
    AllowedValues: 
      - missing
      - breaching
      - ignore
      - notBreaching
    Default: missing
  pNamespace:
    Type: String
    Description: What is the namespace of the resource metric to be monitored?
    Default: Namespace
  pDimension:
    Type: String
    Description: What dimension do you want to monitor?
    Default: Dimension
  pStatistic:
    Type: String
    AllowedValues:
      - Sum
      - Average
      - Maximum
      - Minimum
      - SampleCount
    Description: What statistic would you like to monitor for?
    Default: Average
  pMetric:
    Type: String
    Default: Metric
    Description: What Metric would you like to monitor?
  pComparisonOperator:
    Type: String
    AllowedValues:
      - GreaterThanOrEqualToThreshold
      - GreaterThanThreshold
      - GreaterThanUpperThreshold
      - LessThanLowerOrGreaterThanUpperThreshold
      - LessThanLowerThreshold
      - LessThanOrEqualToThreshold
      - LessThanThreshold
    Default: GreaterThanThreshold


Conditions:
  cMakeSNS: !Equals
    - !Ref pExistingOrCreateSNS
    - Create
  cExistingSNS: !Equals
    - !Ref pExistingOrCreateSNS
    - Existing

Resources:
  rResourceSNSTopic:
    Type: AWS::SNS::Topic
    Condition: cMakeSNS
    Properties:
      Subscription:
        - Endpoint: !Ref pSNSEmail
          Protocol: email
      TopicName: !Ref pSNSTopicFriendlyName

  rNewResourceAlarm:
    Type: AWS::CloudWatch::Alarm
    Condition: cMakeSNS
    Properties:
      ComparisonOperator: !Ref pComparisonOperator
      MetricName: !Ref pMetric
      Statistic: !Ref pStatistic
      EvaluationPeriods: !Sub ${pEvaluationPeriods}
      Period: !Sub ${pPeriodLength}
      Namespace: !Ref pNamespace
      Threshold: !Sub ${pThreshold}
      Dimensions:
        - Name: !Ref pDimension
          Value: !Ref pUniqueResourceName
      TreatMissingData: !Ref pMissingData
      AlarmActions: 
        - !Ref rResourceSNSTopic

  rExistingResourceAlarm:
    Type: AWS::CloudWatch::Alarm
    Condition: cExistingSNS
    Properties:
      ComparisonOperator: !Ref pComparisonOperator
      MetricName: !Ref pMetric
      Statistic: !Ref pStatistic
      EvaluationPeriods: !Ref pEvaluationPeriods
      Period: !Ref pPeriodLength
      Namespace: !Ref pNamespace
      Threshold: !Ref pThreshold
      Dimensions:
        - Name: !Ref pDimension
          Value: !Ref pUniqueResourceName
      TreatMissingData: !Ref pMissingData
      AlarmActions: 
        - !Ref pExistingSNSID


Outputs:
  oExistingOrCreateSNS:
    Value: !Ref pExistingOrCreateSNS
    Description: Did the user select to create a new SNS topic, or use an existing one? 
    Export:
      Name: !Sub ${AWS::StackName}-NewOrExisting
  oSNSTopicFriendlyName:
    Value: !Ref pSNSTopicFriendlyName
    Condition: cMakeSNS
    Description: What friendly name was given to the SNS Topic.
    Export:
      Name: !Sub ${AWS::StackName}-NewSNSName
  oSNSEmail:
    Condition: cMakeSNS
    Value: !Ref pSNSEmail
    Description: What email endpoint was given for the new SNS
    Export:
      Name: !Sub ${AWS::StackName}-NewSNSEmail
  oExistingSNSID:
    Condition: cExistingSNS
    Value: !Ref pExistingSNSID
    Description: What was the existing SNS Topic ID used
    Export:
      Name: !Sub ${AWS::StackName}-ExistingSNS
  oUniqueResourceName:
    Value: !Ref pUniqueResourceName
    Description: Unique Resource Name of resource selected to monitor
    Export:
      Name: !Sub ${AWS::StackName}-ResourceID
  oThreshold:
    Value: !Ref pThreshold
    Description: Threshold chosen
    Export:
      Name: !Sub ${AWS::StackName}-Threshold
  oPeriodLength:
    Value: !Ref pPeriodLength
    Description: Period length chosen
    Export:
      Name: !Sub ${AWS::StackName}-Period
  oEvaluationPeriods: 
    Value: !Ref pEvaluationPeriods
    Description: How many ecaluation periods were assigned.
    Export:
      Name: !Sub ${AWS::StackName}-EvalutionPeriods
  oMissingData:
    Value: !Ref pMissingData
    Description: How is missing data being treated
    Export:
      Name: !Sub ${AWS::StackName}-MissingData
  oNamespace:
    Value: !Ref pNamespace
    Description: What namespace is being used
    Export:
      Name: !Sub ${AWS::StackName}-NameSpace
  oDimensions:
    Value: !Ref pDimension
    Description: What dimension is being used
    Export:
      Name: !Sub ${AWS::StackName}-Dimension
  oStatistic:
    Value: !Ref pStatistic
    Description: What statistic is being used
    Export:
      Name: !Sub ${AWS::StackName}-Stastitic
  oMetric:
    Value: !Ref pMetric
    Description: What metric is being used
    Export:
      Name: !Sub ${AWS::StackName}-Metric
  oComparisonOperator:
    Value: !Ref pComparisonOperator
    Description: What comparison operator is being used
    Export:
      Name: !Sub ${AWS::StackName}-ComparisonOperator