CloudFormation: Lambda Error Notification

CFN-LambdaErrorNotify.yaml

## Add SNS Notifications of Lambda failures.  Only alarms on text sent to CloudWatch logs

Parameters:
  AppName:
    Type: String
  SNSEmail:
    Type: String
Resources:
  Lambda:
    Type: AWS::Serverless::Function
    Properties:
      Description: Do a lambda thing!
      FunctionName: !Ref AppName
      ## More properties needed..
  LambdaLogGroup:
    Type: AWS::Logs::LogGroup
    Properties:
      LogGroupName: !Sub "/aws/lambda/${Lambda}"
      RetentionInDays: 14
  FailedAuthMetricFilter:
    Type: AWS::Logs::MetricFilter
    Properties: 
      LogGroupName: !Ref LambdaLogGroup
      FilterPattern: >- 
        "[ERROR]"
      MetricTransformations:
        - MetricValue: '1'
          DefaultValue: '0'
          MetricNamespace: LambdaMetrics
          MetricName: LambdaFailures
  LambdaErrorAlarm:
    Type: AWS::CloudWatch::Alarm
    Properties:
      AlarmName: github_gobbler_lambda_error
      AlarmDescription: >-
        A CloudWatch Alarm that triggers if there are errors returned from the Lambda
      MetricName: LambdaFailures
      Namespace: LambdaMetrics
      Statistic: Sum
      Period: '300'
      EvaluationPeriods: '1'
      Threshold: '1'
      ComparisonOperator: GreaterThanOrEqualToThreshold
      AlarmActions:
        - Ref: NotifySNS
      TreatMissingData: notBreaching
  NotifySNS:
    Type: AWS::SNS::Topic
    Condition: NotifyOnLambdaError
    Properties: 
      DisplayName: !Sub ${AppName}-Lambda-Error
      Subscription: 
        - Endpoint: !Ref SNSEmail
          Protocol: Email
      TopicName: !Sub ${AppName}Error