[SOLVED] Why do I still get a warning about "Running pip as the 'root' user" inside a Docker container?

Why do I still get a warning about "Running pip as the 'root' user" inside a Docker container?

I made a simple image of my python Django app in Docker, using this Dockerfile:

FROM python:3.8-slim-buster

WORKDIR /app
COPY requirements.txt requirements.txt
RUN pip install -r requirements.txt
COPY . .
CMD ["python", "manage.py", "runserver", "0.0.0.0:8000"]

And building it using:

sudo docker build -t my_app:1 .

But after building the container (on Ubuntu 20.04) I get this warning:

WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead

Why does it throw this warning if I am installing Python requirements inside my image? Can I actually break my system this way?

Solution

The way your container is built doesn't add a user, so everything is done as root.

You could create a user and install to that users's home directory by doing something like this;

FROM python:3.8.3-alpine

RUN pip install --upgrade pip

RUN adduser -D myuser
USER myuser
WORKDIR /home/myuser

COPY --chown=myuser:myuser requirements.txt requirements.txt
RUN pip install --user -r requirements.txt

ENV PATH="/home/myuser/.local/bin:${PATH}"

COPY --chown=myuser:myuser . .

CMD ["python", "manage.py", "runserver", "0.0.0.0:8000"]