[GENERAL ISSUE] String concatenation with literal and variable

[jkruse14]

Describe the issue
A clear and concise description of what the issue is.

There does not seem to be a way to combine two strings, either inline or through variable definition, to allow for the combination of a string literal and a variable

Any examples

let bucket_name = "s3/%BucketName"
LoggingConfiguration.LogFilePrefix == %bucket_name

let bucket_name = "s3/"+%BucketName
LoggingConfiguration.LogFilePrefix == %bucket_name

LoggingConfiguration.LogFilePrefix == "s3/"+%BucketName

Version

> cfn-guard --version
cfn-guard 3.0.3

Operating System:
Windows

OS Version
Windows 10 Pro

Additional context
The outcome I would like to achieve in my specific context is to create a rule that enforces the LoggingConfiguration.LogFilePrefix of an S3 Bucket to match the pattern of s3/<bucket name>, so if I have this configuration:

Type: AWS::S3::Bucket
    Properties:
      BucketName: !Sub cfn-guard-test-${AWS::AccountId}-${AWS::Region}
      ...
      LoggingConfiguration:
        DestinationBucketName: !Sub dibh-${AWS::AccountId}-${AWS::Region}-common-logging
        LogFilePrefix: !Sub s3/cfn-guard-test-${AWS::AccountId}-${AWS::Region}

I could write something like

let log_file_prefix = "s3/"+BucketName
LoggingConfiguration.LogFilePrefix == %log_file_prefix

or with a function

let log_file_prefix = join_strings(["s3", BucketName], "/")
LoggingConfiguration.LogFilePrefix == %log_file_prefix

[joshfried-aws]

Hi @jkruse14, you. are correct this is not currently possible using cfn-guard. While we do have a join function, this wouldnt work for the use case you have described. I think we could track this as part of #479

[joshfried-aws]

closing this issue out, as mentioned above we are going to track this as part of #479