@manics Thanks. I actually posted these items in a different post. See the THIS LINK for the files.
Don’t worry that that post focuses on getting systemd(5) working because the three files (./jupyterhub_config.py, ./docker-compose.yml and ./.env) are the same as if I would post them here. Of course I’ve updated jupyterhub_config.py since that post (… updates corresponding to what you’re seeing on this post), but now you have the entire files, top-to-bottom.
P.S. I tried posting this on GitHub (in JupyterHub and in DockerSpawner), but they keep closing them and directing me here.