'docker exec' environment different from 'docker run'/'docker attach' environment? - django

Question

I recently tried creating a docker environment for developing django projects.
I've noticed that files created or copied via the Dockerfile are only accessible when using 'docker run' or 'docker attach', in which case for the latter, you would be able to go in and see whatever files you've moved in their appropriate places.
However, when running 'docker exec', the container doesn't seem to show any trace of those files whatsoever. Why is this happening?
Dockerfile
############################################################
# Dockerfile to run a Django-based web application
# Based on an Ubuntu Image
############################################################
# Set the base image to use to Ubuntu
FROM ubuntu:14.04
# Set env variables used in this Dockerfile (add a unique prefix, such as DOCKYARD)
# Local directory with project source
ENV DOCKYARD_SRC=hello_django
# Directory in container for all project files
ENV DOCKYARD_SRVHOME=/srv
# Directory in container for project source files
ENV DOCKYARD_SRVPROJ=/srv/hello_django
# Update the default application repository sources list
RUN apt-get update && apt-get -y upgrade
RUN apt-get install -y python python-pip
# Create application subdirectories
WORKDIR $DOCKYARD_SRVHOME
RUN sudo mkdir media static logs
# Copy application source code to SRCDIR
COPY $DOCKYARD_SRC $DOCKYARD_SRVPROJ
# Install Python dependencies
RUN pip install -r $DOCKYARD_SRVPROJ/requirements.txt
# Port to expose
EXPOSE 8000
# Copy entrypoint script into the image
WORKDIR $DOCKYARD_SRVPROJ
COPY ./docker-entrypoint.sh /
With the above Dockerfile, my source folder hello_django is copied to its appropriate place in /srv/hello_django, and my docker-entrypoint.sh was moved to root successfully as well.
I can confirm this in 'docker run -it bash'/'docker attach', but can't access any of them through 'docker exec -it bash", for example.
(Dockerfile obtained from this tutorial).
Problem Demonstration
I'm running docker through vagrant, if that's relevant.
Vagrantfile
config.vm.box = "hashicorp/precise64"
config.vm.network "forwarded_port", guest: 8000, host: 8000
config.vm.provision "docker" do |d|
d.pull_images "django"
end