Boto3: [Question] - SyntaxError when using s3 client on aws-sam-local and Python3.7

[maoo]

_Original issue was created on https://github.com/awslabs/aws-sam-local/issues/59_

_Apologies in advance if this is not the right place to open this issue, I don't have an extensive experience with aws-sam-local or Python, so I may be missing something really stupid._

I am building a Python logic to run on AWS Lambda and chose aws-sam-local as framework.

I came up with a simple Python test file which works fine when executed with python2.7:

pip install boto3 -t .
python -c 'from test import test1; test1(None,None)'

However, when trying to use python3.6 as Runtime (as originally mentioned in template.yaml), I get a SyntaxError: invalid syntax on line client = boto3.client('s3'); the full history is on https://gist.github.com/maoo/2175a1c4b75a80c7271943591afb4920#file-error-log

Steps to reproduce the issue:

1. install npm
2. npm install -g aws-sam-local
3. Download test.py and template.yaml locally, same folder
4. echo '{}' | sam local invoke Test

Switching the Runtime to python2.7 fixes the issue; anyone else having the same problem? Any idea what the cause could be?

TIA

[joguSD]

Not sure why this would fail, but a SyntaxError is surely not related to boto3. For your sanity, I validated that your sample code is syntactically correct for both 2.7 and 3.6. The issue is in "/var/task/concurrent/futures/_base.py" which I'm going to assume is some kind of issue with the image being used to run the lambda function. That is, the environment is misconfigured.

[syedautherabbas]

So this happens with the serverless framework too, if I use s3 = boto3.resource('s3') or s3 = boto3.client('s3') in my progrram and build with serverless env as python 3.6 , this pops up.

[maxalbrecht100]

I know this is an old thread, but in case anyone else finds this useful - I was having a similar issue when trying to use the AWS Toolkit Codelens functionality to debug a python lambda function locally for my SAM app. In the end it turned out that it didn't like that there was a dash in the file name that the handler was in, once I replaced the dash in the name with an underscore (remember to also change it in your template.yaml) I no longer got back the syntax error.

I found it really useful to go to the folder created by the Debug Locally functionality and look at the __vsctk__debug.py file in a text editor to find out what was the problem.