RFC 0014: New Intrinsic Function to Convert Template Block to JSON String

[mluk-aws]

Language Enhancement Request For Comment

This is a request for comments about a new intrinsic function to convert template blocks to JSON strings. See #14 for
additional details.

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Licensing

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[jlhood]

Looks good. Just want to add syntax highlighting to examples. This is a good practice in general but for this feature in particular, it emphasize the syntax highlighting benefit of Fn::ToJsonString.

[benkehoe]

This is unrelated to the RFC itself, but I will say it in every forum available to me: no new resources should be allowed to ship that require string-containing-JSON, even if the underlying APIs require it (the resource handler should perform the conversion).

[iann0036]

Per offline conversation, I would suggest that instead of making this an explicit action, we simply refer to the specification / registry type to determine the appropriate type at runtime. If the provided input is an object but the spec expects a string, simply perform the transformation automatically.

[benkehoe]

determine the appropriate type at runtime

I'm skeptical of this. I would be fine if the type of these properties was "string containing JSON", but when it's just "string" I think coercing every string property value to string is removing the ability to lint and provide up-front errors, as you essentially eliminate any type errors for string-valued properties.