Support Python3

[include]

hi,

Moments ago I've removed the old npm sam cli and upgraded to the latest with pip when I realised this is a python2 app. Are any plans to add python3 support to it?

Thanks in advance;; and thanks a lot for this sam-cli/local :)

Cheers,
Francisco

[jfuss]

@include Yes. Some of our dependencies are not built for py3 just yet. We are working resolving this. We built the CLI to be py3 compatible from the start, just need all dependencies to support py3 first :)

[sanathkr]

Yes! Python3 support is coming soon (not dates yet but definitely happening). We were aware of this limitation at launch but wanted to deliver all the exciting new features first rather than holding off for Python3.

I will update the Issue title to be more descriptive of the question and use this as a tracking issue.

[kadrach]

A simple warning like

$ sam
This tool does not support python3, please install python2.

would be nice :)

Adding onto the point by @kadrach. It would be nice if there was a warning in the documentation that AWS CLI also needs to be using Python 2 and not Python 3.6.5

[jfuss]

@josephmcasey We have a very small note in the README.rst about this: https://github.com/awslabs/aws-sam-cli#windows-linux-macos-with-pip-recommended. I agree it can be clearer and should be but we are quickly working towards Py3 for both SAM CLI and SAM.

While adding this into the cli would be nice @kadrach, it is not possible since you wouldn't be able to pip install it.