uwisg：ModuleNotFoundError：没有名为“flask”的模块

Question

I am trying to make a flask application, and I am following the well known tutorials out there. I am using docker containers, so I don't need virtual environments, as the containers are already isolated environments.

that's my project folder for the flask app:

flask
├── Dockerfile
├── app
│   ├── __init__.py
│   ├── routes.py
│   ├── static
│   └── templates
│       ├── index.html
│       └── test.html
├── requirements.txt
├── run.py
└── uwsgi.ini

When starting up the container with docker-compose, I get the following error.

Traceback (most recent call last):
  File "run.py", line 1, in <module>
    from app import app #as application
  File "./app/__init__.py", line 1, in <module>
    from flask import Flask
ModuleNotFoundError: No module named 'flask'
unable to load app 0 (mountpoint='') (callable not found or import error)

I have read many other questions with such an error, but none of those solutions helped or had to do with venv (which I am not using). So I hope someone can pinpoint, where the problem might be.

I have installed flask in Dockerfile with

RUN python3 -m pip install  --disable-pip-version-check --no-cache-dir -r /tmp/requirements.txt

(I also just used pip3 install... but it does not make a difference, flask is installed either way). from the build log:

Successfully installed Jinja2-3.0.3 MarkupSafe-2.0.1 Werkzeug-2.0.2 click-8.0.3 flask-2.0.2 itsdangerous-2.0.1

## run.py
from app import app

This is the import that seems to fail:

## __init__.py
from flask import Flask
app = Flask(__name__)
from app import routes

extract from uwisg.ini:

[uwsgi]
plugin = python3
wsgi-file = run.py
callable = app

After starting the container with docker-compose, I exec into the container, start a Python3 interactive shell and have no problems at all doing from flask import Flask .

I have tried running the container as root but that did not change anything.

Any ideas? thanks!

Answer 1

Ok, after more rinse and repeat trying, I figured it out.

In my Dockerfile I also set the PYTHONPATH to my workspace:

ENV PYTHONPATH "${PYTHONPATH}:/workspace/flask"
ENV PYTHONPATH "${PYTHONPATH}:/workspace/flask/app"

and site-packages apperently could not be accessed by Python anymore.

I also had to add this:

ENV PYTHONPATH "${PYTHONPATH}:/usr/local/lib/python3.11/site-packages"

I have no idea, why this path was not accessible for Python? Did I overwrite sys.path when using ENV PYTHONPATH ? Should this not be additive to sys.path?