!Ref to local path not supported for AWS::Serverless::LayerVersion

[hoffa]

Description:

See aws/serverless-application-model#2533 (comment) and linked issues for context.

Given the following template where CodePath is a local path:

Transform: AWS::Serverless-2016-10-31
Parameters:
  CodePath:
    Type: String
Resources:
  MyLayerVersion:
    Type: AWS::Serverless::LayerVersion
    Properties:
      ContentUri: !Ref CodePath

Deployment fails:

Resource with id [MyLayerVersion0a209abe4f] is invalid. 'ContentUri' requires Bucket and Key properties to be specified.

Steps to reproduce:

sam init --name sam-app --runtime python3.8 --dependency-manager pip --app-template hello-world
cd sam-app

Replace template.yaml with:

Transform: AWS::Serverless-2016-10-31
Parameters:
  CodePath:
    Type: String
Resources:
  MyLayerVersion:
    Type: AWS::Serverless::LayerVersion
    Properties:
      ContentUri: !Ref CodePath

Deploy:

sam build --parameter-overrides CodePath=hello_world/
sam deploy --guided --parameter-overrides CodePath=hello_world/

Observed result:

The template passed to the SAM transform is the following (i.e. doesn't include the packaged assets):

Transform: AWS::Serverless-2016-10-31
Parameters:
  CodePath:
    Type: String
Resources:
  MyLayerVersion:
    Type: AWS::Serverless::LayerVersion
    Properties:
      ContentUri:
        Ref: CodePath
    Metadata:
      SamResourceId: MyLayerVersion

However, with CodeUri in AWS::Serverless::Function, the following template is deployable and the assets are packaged as expected:

Transform: AWS::Serverless-2016-10-31
Parameters:
  CodePath:
    Type: String
Resources:
  MyFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: !Ref CodePath
      Handler: app.lambda_handler
      Runtime: python3.9

Expected result:

Expected !Ref to work with local paths, similar to CodeUri.

Additional environment details (Ex: Windows, Mac, Amazon Linux etc)

1. OS: macOS
2. sam --version: SAM CLI, version 1.72.0
3. AWS region: us-west-2

{
  "version": "1.72.0",
  "system": {
    "python": "3.8.16",
    "os": "macOS-13.2.1-x86_64-i386-64bit"
  },
  "additional_dependencies": {
    "docker_engine": "Not available",
    "aws_cdk": "1.101.0 (build 149f0fc)",
    "terraform": "1.3.7"
  }
}

Add --debug flag to command you are running

[sriram-mv]

Tagging as area/intrinsics. We should create a parent ticket for all intrinsic issues and link it.