Support !Select when the array of elements is a !Split on !Ref

[gmarciani]

Hello,

this project is great, but I'm facing a blocker, which I need help for.

I'm using cloud-radar pointing to this commit 648bc29 (it contains a fix I needed).

The following template:

Resources:
  DummyEcrImage:
    Type: AWS::ImageBuilder::Image
    Properties:
      ContainerRecipeArn: "ContainerRecipeArn"
      EnhancedImageMetadataEnabled: true
      InfrastructureConfigurationArn: "InfrastructureConfigurationArn"
      ImageTestsConfiguration:
        ImageTestsEnabled: false

  DummyParameter1:
    Type: AWS::SSM::Parameter
    Properties:
      Type: String
      Value: !Select [2, !Split ['/', !Ref DummyEcrImage]]

returns the following error when template.create_stack() is called:

        try:
            return items[index]
        except IndexError:
>           raise IndexError(
                "Fn::Select - List size is smaller than the Index given."
            ) from None
E           IndexError: Fn::Select - List size is smaller than the Index given.

May you please support this use case?

Thank you,
Giacomo

[dhutchison]

Hi Giacomo,

Yep I'll take a look at this soon. In the interim (since you are already running off a commit that hasn't been released into a version yet), if you take the latest develop branch you will be able to take advantage of the fix in #399. This will require a change to your template however.

Instead of using !Ref DummyEcrImage, use !GetAtt DummyEcrImage.Arn. These are equivalent based on the resource type documentation, but then you can use the attribute-values metadata from that linked PR.

I'll aim to add some equivalent override functionality for Ref.

[gmarciani]

Hi David,

thank you for suggesting the workaround. Unfortunately it does not work for us as we cannot modify the template.
However, injecting custom replacement of attributes and tokens is a good idea to quickly unblock.

What about adding the possibility to inject those in the create_stack call w/o changing the input template?

Example for this specific case:

stack = template.create_stack(replacements={"!Ref DummyEcrImage": "arn:aws:ecr:region:012345678910:repository-namespace/repository-name"})