Databases settings and docker

[tame sapphire]

Hi everyone. Please help me figure this out. I have two options specified in my Django settings file for the DATABASES. If DEBUG=True, the project uses sqlite3 and if DEBUG=False, it uses PostgreSQL.
So, here's the question: when I start up the project locally in Docker containers, I use a PostgreSQL container (as stated in the Docker Compose file), even though in my .env file DEBUG=True, and Django should theoretically want sqlite3 (as specified in the Django settings). Why isn't there a conflict?

DATABASES = {
    'production': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': os.getenv('POSTGRES_DB', 'django'),
        'USER': os.getenv('POSTGRES_USER', 'django'),
        'PASSWORD': os.getenv('POSTGRES_PASSWORD', ''),
        'HOST': os.getenv('DB_HOST', ''),
        'PORT': os.getenv('DB_PORT', 5432)
    },
    'dev': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}
DATABASES['default'] = DATABASES['dev' if DEBUG else 'production']

[tight gulch]

I'm not sure what exactly is your issue, do you want to use postgresql in when you develop locally with docker? I'd rephrase and expand on your question "why isn't there a conflict".

In any case you might benefit from using https://pypi.org/project/dj-database-url/, which would allow you to set DATABASE_URL=sqlite://dev.db and DATABASE_URL=postgres:///db for example and not have to worry about setting the ENGINE manually

[worn path]

If your docker compose file says to start a postgres container, docker will start it. If your settings point to SQLite, the postgres container will just sit idle with no connections and no data.