"technically json is already valid yaml"... the YAML people SAY that, but can you actually do that? I think we tried it once and it failed miserably. -- Frost

I suppose it depends on how compliant the parser in question is, but I don't recall facing any issues with this. You can mix and match too. Parts in json and parts in (non-json) yaml. I've done this a few times in Ansible I think.