aws cloudformation validate-template should check for duplicate resource names

[autopulated]

Currently both update-stack and validate-template silently ignore duplicate resources keys in a JSON template file, this is a source of errors that can be hard to notice in large templates!

[kyleknap]

So ideally I think this validation logic should live upstream in the service logic. The CLI really only takes parameters provided through command line options, converts it into an HTTP request, and parses/prints out the HTTP response to the user. If the validation lived in the service, all tools and clients accessing the API will have the validation logic available to them and not just the CLI.

I would recommend starting a thread in the AWS Developer Forums as there is not much that can be done from the CLI's side. Let us know if you have anymore questions.

[autopulated]

So, the reason to do this in the client is (as I understand it), a --template-body file will be loaded by botocore (https://github.com/boto/botocore/blob/00819aac50957241436d980af8063c5a0b578c85/botocore/handlers.py#L132) – and in the process duplicate keys are silently dropped.

Should I open an issue on botocore for that?

[stealthycoin]

The behavior of duplicate keys is undefined under the JSON spec, since we simply use the python implementation we will have whatever behavior they have decided on.