PORT environment variable missing

[timoles]

Hey, I just followed this tutorial, and the PORT variable is missing from the .env file.

When setting up the .env file according to the tutorial:

cat .env

>CLIENT_ORIGIN_URL=http://localhost:4040
>AUTH0_AUDIENCE=https://xxx
>AUTH0_DOMAIN=xxx.eu.auth0.com

docker-compose up

The following error message is presented (notice the second to last line, Missing PORT environment variable):

Recreating api_flask_python_hello-world_api_1 ... done
Attaching to api_flask_python_hello-world_api_1
api_1  | Failed to read config file: /app/gunicorn.conf.py
api_1  | Traceback (most recent call last):
api_1  |   File "/app/common/utils/__init__.py", line 5, in safe_get_env_var
api_1  |     return environ[key]
api_1  |   File "/usr/lib/python3.9/os.py", line 679, in __getitem__
api_1  |     raise KeyError(key) from None
api_1  | KeyError: 'PORT'
api_1  |
api_1  | During handling of the above exception, another exception occurred:
api_1  |
api_1  | Traceback (most recent call last):
api_1  |   File "/packages/gunicorn/app/base.py", line 111, in get_config_from_filename
api_1  |     spec.loader.exec_module(mod)
api_1  |   File "<frozen importlib._bootstrap_external>", line 790, in exec_module
api_1  |   File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
api_1  |   File "/app/gunicorn.conf.py", line 10, in <module>
api_1  |     bind = f"0.0.0.0:{safe_get_env_var('PORT')}"
api_1  |   File "/app/common/utils/__init__.py", line 7, in safe_get_env_var
api_1  |     raise NameError(f"Missing {key} environment variable.")
api_1  | NameError: Missing PORT environment variable.
api_flask_python_hello-world_api_1 exited with code 1