How does a .env file relate to Python / Django?

Question

I'm pretty new to Django / Python, and I'm trying to figure out how a .env file relates to a Django project.

Example .env:

DATABASE_URL=postgres://postgres_user@db:xxxx/postgres_db
DJANGO_SETTINGS_MODULE=spare.settings.dev
SECRET_KEY=example

I did manage to find this Stack Overflow post, which gives some information, but was hoping for a bit more.

• Do all Django projects have a .env file?
• Do non-Django python projects have a .env file, or is it generally a Django-related thing?
• Where is the .env file typically being called from? In other words, how does the rest of the project know that the .env file exists?

Answer 1

We can only guess because we don't have access to your actual environment.

The .env file may be a container manager thing or something from libraries like python-decouple - for practical effects the .env will be used to populate the environment variables when the container "boots" or will be used to fill instance settings.

There is a common pattern made popular by the Twelve-Factor app: the item III is "Store config in the environment". Then in the settings.py file you use the KEY = os.environ.get('KEY', 'defaul_value'). The idea is to separate instance settings from project settings from code.