Support nested !Select

[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:
  DummyNestedStack:
    Type: AWS::CloudFormation::Stack
    Properties:
      TemplateURL: "https://myendpoint/mytemplate.yaml"

  DummyParameter:
    Type: AWS::SSM::Parameter
    Properties:
      Type: String
      Value: !Select [2, !Split ['/', !Select [0, !Split ['.', !GetAtt [ DummyNestedStack, Outputs.DummyOutput ]]]]]

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.

Notice that a slightly different template succeeds the creation:

Resources:
  DummyNestedStack:
    Type: AWS::CloudFormation::Stack
    Properties:
      TemplateURL: "https://myendpoint/mytemplate.yaml"

  DummyParameter:
    Type: AWS::SSM::Parameter
    Properties:
      Type: String
      Value: !Select [ 0, !Split [ '.', !GetAtt [ DummyNestedStack, Outputs.DummyOutput ] ] ]

so I guess the problem is around nesting !Select

May you please support this use case?

Thank you,
Giacomo

[dhutchison]

Hi Giacomo,

I think this might be similar to what I have just commented on in #414 (comment) . You should be able to use the meta data change from #399 (which is not in a released version yet) to set for tests what you expect Outputs.DummyOutput to be like

[gmarciani]

Thank you for the workaround, David. Unfortunately, changing the input template is not an option for us. I proposed a different approach here to unblock this type of scenarios. Let me know what you think about it.

[dhutchison]

Hey @gmarciani, could you take a look at #428 and see if that works with your use cases (looking at the new example test case)?

Thanks

[gmarciani]

Hi @dhutchison the PR seems addressing the issue. thank you for taking care of it!