E3012 for Fn::Rain::S3Http

[chdanielmueller]

Is this feature request related to a new rule or cfn-lint capabilities?

rules

Describe the feature you'd like to request

I would like to use AWS Rain extensions like !Rain::S3Http without it returning the error E3012 {'Fn::Rain::S3Http': 'substack.yml'} is not of type 'string'.
I tried to write a custom schema without success.

Describe the solution you'd like

Sample Schema which solves this issue
or
Possibility to enable Rain Extensions via cfn-lint config.
e.g. .cfnlintrc

rain: true

Additional context

Sample Template:

AWSTemplateFormatVersion: '2010-09-09'
Description: This template deploys a substck via AWS Rain

Resources:

  SubStack:
    Type: AWS::CloudFormation::Stack
    UpdateReplacePolicy: Delete
    DeletionPolicy: Delete
    Properties:
      TemplateURL: !Rain::S3Http substack.yml
      Parameters:
        Parameter1: Test

Is this something that you'd be interested in working on?

• 👋 I may be able to implement this feature request

Would this feature include a breaking change?

• ⚠️ This feature might incur a breaking change