A Dockerfile is a text document that contains all the commands an administrator could call on the command line to assemble an image. It is used to create a Docker image, which can then be used to create Docker containers.
Example:
FROM ubuntu:18.04
RUN apt-get update && apt-get install -y
python3-pip
python3-dev
COPY . /app
WORKDIR /app
RUN pip3 install -r requirements.txt
ENTRYPOINT [“python3”]
CMD [“app.py”]