Setting up Dockerfile to use non-root user - docker

Question

I'm currently having an issue when I tried to run pip as a non-root user in my Dockerfile. When It starts to build the wheel it gives these warnings WARNING: The script foo is installed in '/home/myuser/.local/bin' which is not on PATH. for pep8, sqlformat, isort, gunicorn, django-admin, epylint, pylint, pyreverse, and symilar.
In the current code I have, the build fails with the error COPY failed: stat usr/src/app/wheels: file does not exist when it tries to run COPY --from=builder /usr/src/app/wheels /wheels although it was failing earlier before I took out --wheel-dir /usr/src/app/wheels from line 35.
###########
# BUILDER #
###########
# pull official base image
FROM python:3.9.4-alpine as builder
# set work directory
WORKDIR /usr/src/app
# set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1
# install psycopg2 dependencies
RUN apk update \
&& apk add postgresql-dev gcc python3-dev musl-dev
# lint
RUN pip install --upgrade pip
RUN pip install flake8==3.9.2
COPY . .
RUN flake8 --ignore=E501,F401 .
# install dependencies
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 . .
WORKDIR /usr/src/app
RUN pip wheel --no-cache-dir --no-deps --wheel-dir /usr/src/app/wheels -r requirements.txt
#########
# FINAL #
#########
# pull official base image
FROM python:3.9.4-alpine
# create directory for the app user
RUN mkdir -p /home/app
# create the app user
RUN addgroup -S app && adduser -S app -G app
# create the appropriate directories
ENV HOME=/home/app
ENV APP_HOME=/home/app/web
RUN mkdir $APP_HOME
RUN mkdir $APP_HOME/staticfiles
RUN mkdir $APP_HOME/mediafiles
WORKDIR $APP_HOME
# install dependencies
RUN apk update && apk add libpq
COPY --from=builder /usr/src/app/wheels /wheels
COPY --from=builder /usr/src/app/requirements.txt .
RUN pip install --upgrade pip
RUN pip install --no-cache /wheels/*
# copy entrypoint.prod.sh
COPY ./entrypoint.prod.sh .
RUN sed -i 's/\r$//g' $APP_HOME/entrypoint.prod.sh
RUN chmod +x $APP_HOME/entrypoint.prod.sh
# copy project
COPY . $APP_HOME
# copy media files
COPY ./media/ $APP_HOME/mediafiles
# chown all the files to the app user
RUN chown -R app:app $APP_HOME
# change to the app user
USER app
# run entrypoint.prod.sh
ENTRYPOINT ["/home/app/web/entrypoint.prod.sh"]
I've tried tinkering with the WORKDIR, ENV PATH, and RUN pip wheel.