AWS have recently upgraded their Cloudformation engine to cope with YAML templates. This is a major boon for us all! 🙂
Here is a small python script that will help convert your json templates over to yaml.
Your joins and user data will likely need a reformat after, however they should still be functional.
print yaml.dump(yaml.load(json.dumps(json.loads(open(sys.argv).read()))), default_flow_style=False)
Alternatively you can use this great site: