CDK tool does not include installed external packages in virtualenvs when deploying

Reproduction Steps

from glom import glom

$ cdk deploy

Error Log

I have a python code that imports glom. I used poetry add glom to install it. Lamda function couldn’t find it. I tried pip install glom, Lambda function still encountered an error.

The error is

[ERROR] Runtime.ImportModuleError: Unable to import module 'auto_tag': No module named 'glom'

Environment

• **CLI Version : 1.18.0 (build bc924bc)
• **Framework Version: Python 3.7
• **OS : MAC OSX
• **Language : Python

Other

By following this solution, I got it to work. However, my project now contains external library that has to be committed to the git project. It looks messy. https://stackoverflow.com/questions/58855739/how-to-install-external-modules-in-a-python-lambda-function-created-by-aws-cdk

I got it to work by running pip install glom --target lambda where lambda is the directory configured in this block

        eventHandler = _lambda.Function(
            self,
            'resourceTagger',
            runtime = _lambda.Runtime.PYTHON_3_7,
            code = _lambda.Code.asset('lambda'), <------- THIS
            handler = 'auto_tag.handler'
        )

But look how messy it is now - https://i.imgur.com/I5YMwtR.png

Are there other ways to do it something that we don’t have to install it in the path specified in _lambda.Code.asset?

---

This is 🐛 Bug Report

[asfourco]

@kgunny There is a way to test your lambda function locally, it requires AWS SAM installed

# from within your project
$ cdk synth > template.yml
# you'll need the function name that cdk assigned to your lambda function
# e.g., fn_start_trainEO123Q2
$ sam local invoke --no-event --debug  _cdk_assigned_function_name_ 

N.B. I’ve had to modify the template to point to the correct asset in cdk.out in the past. Not sure if it’s still the case.

Here’s the mock.sh script I created to run within my cdk python app project for local testing:

#!/bin/bash

# run cdk synth once to look for the function name and put it here
functionName=" GET FROM THE TEMPLATE"

cdk synth | gsed -r 's/^(\s*aws:asset:path:\s*)(asset\w*)/\1cdk.out\/\2/' > template.yml 
sam local invoke --no-event --debug  $functionName 

[c0debreaker]

Your layers worked like a charm! Thanks a lot! 😃