A dumb webserver that has a single GET endpoint /, which accepts a single
url param data, and appends that string as a single line in a file.
The filename is configured in the environment as APPENDONLY_FILENAME.
Run the webserver with ./run.sh, which spins up a gunicorn WSGI wrapping the
flask app, exposing port 80 on the local network.
I want a simple webserver to run from my laptop on a local WIFI network, which I can use to collect sensor data on hobby projects.