Layer is an Invalid Layer Arn, when passing it to a nested Serverless Application

[JohanZackrisson]

Description:

When passing a !Ref to a AWS::Serverless::LayerVersion to a nested AWS::Serverless::Application, sam build returns:
Error: Layer is an Invalid Layer Arn.
when using version 1.21.1

This does not happen in version 1.19.1.

I've minimized a test case, which can be found at:
https://github.com/JohanZackrisson/aws-sam-cli-bug

When passing in a arn string instead of a !Ref, it builds.

Steps to reproduce:

In the main folder do:
Non working test:
pip3 install aws-sam-cli -Iv aws-sam-cli==v1.21.1
sam build

Working test:
pip3 install aws-sam-cli -Iv aws-sam-cli==v1.19.1
sam build

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

1. OS: Mac OS 11.2.3
2. sam --version: 1.21.1
3. AWS region: eu-west-1

[aahung]

Thanks for reporting, it is fixed in #2760 and to be released.

BTW, since 1.20.0, sam build will start to build functions/layers in nested stacks as well, make sure your functions can be built (I see in your example, the lambda folder does not contain a package.json, sam build might fail building that function).

[JohanZackrisson]

Thanks for the feedback. Looking forward to the next release. :)

[aahung]

@JohanZackrisson you are welcome. You can try out our nightly build available at https://github.com/aws/aws-sam-cli/releases to see if it resolves your problem.

[aahung]

released in 1.22.0