Unresolved import if sys.path modified in __init__.py

For projects that include external repos, it would be handy to insert the relative dependency paths ONLY when importing the necessary module.

Here is an example project layout:

Project root
+-- external repo/
      +-- lib/
           +-- config  # defines Config class
      +-- utils/
+-- mypackageA
     +-- __init__.py
     +-- app.py
main.py

In main.py, when an app instance that depends on the Config.py module in the external repo is created, the sys.path must include external repo/lib at the time of importing app:

from mypackageA import app
app.App()

Instead of setting the PYTHONPATH statically, an alternative is to modify sys.path in mypackageA.__init__.py by inserting paths to external repo/lib for the app module to import Config. However, vscode shows unresolved import warnings in this use case.

[aripalo]

I have a bit similar situation, my use case is that I am developing a polyglot monorepo containing multiple AWS Lambda functions. Depending on the use case, they are written in Go, TypeScript and Python.

I try to keep all the functions “contained” in such a way that the folder containing the AWS Lambda function source code has the manifest-file (requirements.txt in Python’s case) and all its dependencies within it. This works well for AWS Lambda as it requires having all the dependencies bundled in the deployment package and also for local development with lambci/lambda Docker.

I’ve initialized each of the Python AWS Lambda functions with their own virtual environment python3 -m venv .venv and then installed vendor dependencies with pip install --upgrade -r requirements.txt (these steps I actually execute inside lambci/lambda Docker containers).

Then in the AWS Lambda source code stored in src/lambda/<function-name>/main.py I have the following:

import logging as log
log.getLogger().setLevel(log.DEBUG)

from pathlib import Path
path = Path(__file__).parent.absolute()
sys.path.insert(0, str(path) + "/.venv/lib/python3.7/site-packages")
log.debug("sys.path:" + str(sys.path))

# After this I import some local dependencies from .venv
import boto3 # Local boto3 version imported as I require newer version than the one in Lambda runtime environment
import cfnresponse
# ... and possibly many more depending on the use case.

Where of course the <function-name> is replaced with the actual function name.

This works fine for the local development in lambci/lambda Docker and in actual AWS Lambda environment.

The problem is that VS Code linter and intellisense doesn’t keep up with that solution.

I can get the VS Code linter & intellisense working by defining in ${workspaceFolder}/.env file the following:

PYTHONPATH=src/lambda/<function-name>/.venv/lib/python3.7/site-packages

The problem here is that I may have several of these functions, let’s say foo and bar. Of course one can set multiple folders into PYTHONPATH separated by os.pathsep, which would mean I’d have to configure:

PYTHONPATH=src/lambda/foo/.venv/lib/python3.7/site-packages:src/lambda/bar/.venv/lib/python3.7/site-packages

… to get the dependencies of foo and bar AWS Lambda functions to work in VS Code.

Unfortunately this becomes problematic as I might have quite many different AWS Lambda functions, so I’d have to define all the different AWS Lambda source code folders into PYTHONPATH which will become tedious task.

So it’d be nice if there was a singular method for defining the dependencies path for these Python AWS Lambda functions, that would work for the actual code (in AWS Lambda & in lambci/lambda) and in VS Code.

[nunesvictor]

In my case the problem was solved replacing

"python.autoComplete.extraPaths": [
    "${workspaceFolder}/src"
],

for

"python.autoComplete.extraPaths": [
    "./src"
],

in my .vscode/settings.json file.

That’s a little odd but it worked