Dockerfile: /bin/sh: 1: apt-get: not found

When building a Docker file, I get the error

"/bin/sh: 1: apt-get: not found"

docker file:

FROM python:3.8
FROM ubuntu:20.04
ENV PATH="/env/bin/activate"
RUN apt-get update -y && apt-get upgrade -y

WORKDIR /var/www/html/
COPY . .
RUN pip install -r requirements.txt
EXPOSE 8000

CMD ["python", "manage.py"]

>Solution :

1. You are setting the PATH to /env/bin/activate and that is then the only place where apt-get is searched for. There is no need to activate a virtual env inside the container, just get rid of that line. pip can install the packages in requirements.txt to the "system" Python without issues.

2. You cannot layer 2 images like you are attempting to do, with multiple FROM statements. Just use FROM python:3.8 and drop the ubuntu. Multiple FROM statements are used in multi-stage builds where you have intermediate images which produce artifacts that are copied to the final image.

So just do:

FROM python:3.8
RUN apt-get update -y && apt-get upgrade -y
WORKDIR /var/www/html/
COPY . .
RUN pip install -r requirements.txt
EXPOSE 8000
CMD ["python", "manage.py"]

.. although why you would put Python code in /var/www/html beats me. Probably you don’t.