AWSTemplateFormatVersion: "2010-09-09"
Description: AWS CloudFormation template to create Random Strings. (qs-1s3s20d5c)
Resources:
  RandomString:
    Type: AWS::Lambda::Function
    Properties:
      Code:
        ZipFile: |
          import base64
          import json
          import logging
          import string
          import random
          import boto3
          from botocore.vendored import requests
          import cfnresponse

          logger = logging.getLogger()
          logger.setLevel(logging.INFO)

          def random_string(size=6):
            return ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(size))

          def lambda_handler(event, context):
            logger.info('got event {}'.format(event))
            responseData = {}

            if event['RequestType'] == 'Create':
              number = int(event['ResourceProperties'].get('Number', 6))
              rs = random_string(number)
              responseData['upper'] = rs.upper()
              responseData['lower'] = rs.lower()

            else: # delete / update
              rs = event['PhysicalResourceId'] 
              responseData['upper'] = rs.upper()
              responseData['lower'] = rs.lower()
                          
            logger.info('responseData {}'.format(responseData))
            cfnresponse.send(event, context, cfnresponse.SUCCESS, responseData, responseData['lower'])

      #FunctionName: !Sub "arn:aws:lambda:${AWS::Region}:${AWS::AccountId}:function:random-string"
      Handler: "index.lambda_handler"
      Timeout: 30
      Role: !GetAtt "LambdaRole.Arn"
      Runtime: python3.9
  # The LambdaRole is very simple for this use case, because it only need to have access to write logs
  # If the lambda is going to access AWS services using boto3, this role must be
  # extended to give lambda the appropriate permissions.
  LambdaRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
          - Effect: Allow
            Principal:
              Service:
                - lambda.amazonaws.com
            Action:
              - sts:AssumeRole
      Path: /
      Policies:
        - PolicyName: "lambda-logs"
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: Allow
                Action:
                  - logs:CreateLogGroup
                  - logs:CreateLogStream
                  - logs:PutLogEvents
                Resource:
                  - !Sub 'arn:${AWS::Partition}:logs:*:*:*'
Outputs:
  RandomStringArn:
    Description: The ARN for the lambda function that was created
    Value: !GetAtt "RandomString.Arn"