AWS Budgets: Update alert thresholds unlimitedly with Lambda

AWSTemplateFormatVersion: "2010-09-09"Description: "Increment alert threshold of AWS Budgets"Parameters:  budgetname:    Type: String    Default: increment-notification  increment:    Type: String    Default: 1  email:    Type: String    AllowedPattern: "^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\\.[a-zA-Z0-9-.]+$"    ConstraintDescription: Must be a valid email address.Resources:  MyTopic:    Type: AWS::SNS::Topic  MyTopicTokenSubscription:    Type: AWS::SNS::Subscription    Properties:      Protocol: email      TopicArn: !Ref MyTopic      Endpoint: !Ref email  MyTopicPolicy:    Type: AWS::SNS::TopicPolicy    Properties:      PolicyDocument:        Statement:          - Action: sns:Publish            Effect: Allow            Principal:              Service: budgets.amazonaws.com            Resource: !Ref MyTopic            Sid: "0"        Version: "2012-10-17"      Topics:        - !Ref MyTopic  UpdateBudgetHandlerServiceRole:    Type: AWS::IAM::Role    Properties:      AssumeRolePolicyDocument:        Statement:          - Action: sts:AssumeRole            Effect: Allow            Principal:              Service: lambda.amazonaws.com        Version: "2012-10-17"      ManagedPolicyArns:        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole  UpdateBudgetHandlerServiceRoleDefaultPolicy:    Type: AWS::IAM::Policy    Properties:      PolicyDocument:        Statement:          - Action: budgets:*            Effect: Allow            Resource: "*"        Version: "2012-10-17"      PolicyName: UpdateBudgetHandlerServiceRoleDefaultPolicy      Roles:        - !Ref UpdateBudgetHandlerServiceRole  UpdateBudgetHandler:    Type: AWS::Lambda::Function    Properties:      Code:        ZipFile: |          import os          import re          import boto3          budget_name = os.environ['BUDGET_NAME']          increment = os.environ['INCREMENT']          def handler(event, context):              print(event)              client = boto3.client('budgets')              account_id = context.invoked_function_arn.split(":")[4]              print("account_id", account_id)              message = event['Records'][0]['Sns']['Message']              print("message", message)              # catch 1 from "Alert Threshold: > $1.00"              match = re.search(r"Alert Threshold: > \$(\d{1,})\.00", message)              if not match:                  print("No Budget Notification. Exit.")                  return              current_value_str = match.groups()[0]              print("current_value", current_value_str)              current_value = int(current_value_str)              next_value = current_value + 10 * int(increment)              response = client.update_notification(                  AccountId=account_id,                  BudgetName=budget_name,                  OldNotification={                      "NotificationType": "ACTUAL",                      "ComparisonOperator": "GREATER_THAN",                      "Threshold": current_value,                      "ThresholdType": "ABSOLUTE_VALUE",                  },                  NewNotification={                      "NotificationType": "ACTUAL",                      "ComparisonOperator": "GREATER_THAN",                      "Threshold": next_value,                      "ThresholdType": "ABSOLUTE_VALUE",                  },              )      Role: !GetAtt UpdateBudgetHandlerServiceRole.Arn      Environment:        Variables:          BUDGET_NAME: !Ref budgetname          INCREMENT: !Ref increment      Handler: index.handler      Runtime: python3.9      Timeout: 10    DependsOn:      - UpdateBudgetHandlerServiceRoleDefaultPolicy      - UpdateBudgetHandlerServiceRole  UpdateBudgetHandlerEventInvokeConfig:    Type: AWS::Lambda::EventInvokeConfig    Properties:      FunctionName: !Ref UpdateBudgetHandler      Qualifier: $LATEST      MaximumRetryAttempts: 0  UpdateBudgetHandlerAllowInvokeStackMyTopic:    Type: AWS::Lambda::Permission    Properties:      Action: lambda:InvokeFunction      FunctionName: !GetAtt UpdateBudgetHandler.Arn      Principal: sns.amazonaws.com      SourceArn: !Ref MyTopic  UpdateBudgetHandlerMyTopic:    Type: AWS::SNS::Subscription    Properties:      Protocol: lambda      TopicArn: !Ref MyTopic      Endpoint: !GetAtt UpdateBudgetHandler.Arn  SetBudgetHandlerServiceRole:    Type: AWS::IAM::Role    Properties:      AssumeRolePolicyDocument:        Statement:          - Action: sts:AssumeRole            Effect: Allow            Principal:              Service: lambda.amazonaws.com        Version: "2012-10-17"      ManagedPolicyArns:        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole  SetBudgetHandlerServiceRoleDefaultPolicy:    Type: AWS::IAM::Policy    Properties:      PolicyDocument:        Statement:          - Action: budgets:*            Effect: Allow            Resource: "*"        Version: "2012-10-17"      PolicyName: SetBudgetHandlerServiceRoleDefaultPolicy      Roles:        - !Ref SetBudgetHandlerServiceRole  SetBudgetHandler:    Type: AWS::Lambda::Function    Properties:      Code:        ZipFile: |          import os          import boto3          budget_name = os.environ['BUDGET_NAME']          sns_arn = os.environ['SNS_ARN']          increment = os.environ['INCREMENT']          client = boto3.client("budgets")          def handler(event, context):              account_id = context.invoked_function_arn.split(":")[4]              # Delete if the budget exists              try:                  client.delete_budget(AccountId=account_id, BudgetName=budget_name)                  print("Deleted the old budget.")              except client.exceptions.NotFoundException:                  pass              # Create new budget              client.create_budget(                  AccountId=account_id,                  Budget={                      "BudgetName": budget_name,                      "BudgetLimit": {"Amount": "100.0", "Unit": "USD"},                      "CostTypes": {                          "IncludeTax": True,                          "IncludeSubscription": True,                          "UseBlended": False,                          "IncludeRefund": False,                          "IncludeCredit": False,                          "IncludeUpfront": True,                          "IncludeRecurring": True,                          "IncludeOtherSubscription": True,                          "IncludeSupport": True,                          "IncludeDiscount": True,                          "UseAmortized": False,                      },                      "TimeUnit": "MONTHLY",                      "BudgetType": "COST",                  },                  NotificationsWithSubscribers=[                      {                          "Notification": {                              "NotificationType": "ACTUAL",                              "ComparisonOperator": "GREATER_THAN",                              "Threshold": threshold,                              "ThresholdType": "ABSOLUTE_VALUE",                              "NotificationState": "OK",                          },                          "Subscribers": [                              {"SubscriptionType": "SNS", "Address": sns_arn},                          ],                      }                      for threshold in range(1, 1 + 10 * int(increment), int(increment))                  ],              )              print("Created a new budget.")      Role: !GetAtt SetBudgetHandlerServiceRole.Arn      Environment:        Variables:          BUDGET_NAME: !Ref budgetname          SNS_ARN: !Ref MyTopic          INCREMENT: !Ref increment      Handler: index.handler      Runtime: python3.9      Timeout: 10    DependsOn:      - SetBudgetHandlerServiceRoleDefaultPolicy      - SetBudgetHandlerServiceRole  SetBudgetHandlerEventInvokeConfig:    Type: AWS::Lambda::EventInvokeConfig    Properties:      FunctionName: !Ref SetBudgetHandler      Qualifier: $LATEST      MaximumRetryAttempts: 0  ScheduleRule:    Type: AWS::Events::Rule    Properties:      ScheduleExpression: cron(0 0 1 * ? *)      State: ENABLED      Targets:        - Arn: !GetAtt SetBudgetHandler.Arn          Id: Target0  ScheduleRuleAllowEventRuleStackSetBudgetHandler:    Type: AWS::Lambda::Permission    Properties:      Action: lambda:InvokeFunction      FunctionName: !GetAtt SetBudgetHandler.Arn      Principal: events.amazonaws.com      SourceArn: !GetAtt ScheduleRule.Arn