Cloudformation Lamda Random Value

lambda.aws.cloudformation.yml

  # Just adding support for a lambda
  LambdaExecutionRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Principal:
              Service:
                - lambda.amazonaws.com
            Action:
              - sts:AssumeRole
      Policies:
        - PolicyName: allowLambdaLogging
          PolicyDocument:
            Version: '2012-10-17'
            Statement:
              - Effect: 'Allow'
                Action:
                  - 'logs:*'
                Resource: '*'

  # Generate a random color for the text in the webserver
  # Taken from https://www.itonaut.com/2018/01/03/generate-passwords-in-aws-cloudformation-template/
  LambdaFunction:
    Type: AWS::Lambda::Function
    Properties:
      Code:
        ZipFile: >
          const response = require('cfn-response');

          exports.handler = (event, context) => {
            // https://stackoverflow.com/a/5365036/7602110
            const responseData = {RandomColor: `#${((1<<24) * Math.random() | 0).toString(16)}`};

            response.send(event, context, response.SUCCESS, responseData);
          };
      Handler: index.handler
      Runtime: nodejs12.x
      Role: !GetAtt LambdaExecutionRole.Arn
      MemorySize: 128
      Timeout: 20

  # Custom Resource
  ColorString:
    Type: AWS::CloudFormation::CustomResource
    Properties:
      Length: 7
      ServiceToken: !GetAtt LambdaFunction.Arn

Usage:

Color: !GetAtt ColorString.RandomColor