Hi @John_Fitton,
Sure, you can just add the following lines to the Dockerfile to clone in the apps module:
RUN git clone https://github.com/emoncms/app.git /var/www/html/Modules/graph/app
In fact since this is a good suggestion I have modified the Dockerfile myself to include the app module
You will need to pull in the changes then rebuild the container:
git pull
docker-compose build
docker-compose up