This project is a very simple URL Shortener made using Django and Python. To deploy it just folow the instructions on their documentation (with a few minor details).
The environment variable DJANGO_SECRET_KEY should be present the moment the app is started, meaning you should either load an environment file before starting the app (you can do this where you import your application, if you are using WSGI), specifying in the command line if you are using manage.py's runserver command, or manually add the variable to os.environment. Here's an example:
export DJANGO_SECRET_KEY=`openssl rand -hex 64`
python3 manage.py runserver
This will use the openssl command to create a strong key.