The dockerfile has not changed, but the file outside the container corresponding to workdir has changed.

1. Is this necessary? If so, is it to use Docker Compose-Up to automatically simplify the process?

2. If not, is it because of my dockerfile problem?
   Dockerfile is as follows:

   FROM ubuntu
    MAINTAINER Tarty.Phoenix   <tartyphoenix@gmail.com >
    RUN apt-get update
    RUN apt-get install -y -q python-all python-pip libffi-dev
    RUN apt-get install -y -q python-dev build-essential
    ADD ./flask_pure/requirements.txt /tmp/requirements.txt
    RUN pip install -qr /tmp/requirements.txt
    
    ADD ./flask_pure /opt/flask_pure/
    WORKDIR /opt/flask_pure
    
    EXPOSE 80
    CMD ["python", "manage.py", "runserver"]