Flask

init_app loads, copies every uppercase variable into app.config coerced to its type, and adds a context processor that hands client variables to your templates as envless.

from flask import Flask

from envless_env.flask import init_app


def create_app() -> Flask:
    app = Flask(__name__)
    init_app(app)

    return app

A variable named SECRET_KEY becomes Flask's secret key, SQLALCHEMY_DATABASE_URI configures Flask-SQLAlchemy, and a boolean named DEBUG arrives as a real bool. Config keys follow Flask's own rule, so a lowercase name is skipped there and still readable through env. Pass config=False to load without touching app.config.

init_app returns the same dict that load() returns, and raises LoadError if the load fails, so create_app stops before the app serves a request.

Client variables in templates#

Every variable marked client in Envless is available in Jinja as envless. Server variables are not in it.

<script>
    window.API_URL = {{ envless.PUBLIC_API_URL|tojson }};
</script>

Reading elsewhere#

Outside the app factory, read through env as anywhere else. init_app loads the shared store, so a blueprint, a CLI command or a Celery task in the same process sees the same values.

from flask import Blueprint

from envless_env.server import env

billing = Blueprint('billing', __name__)


@billing.get('/plans')
def plans() -> dict[str, object]:
    return {'currency': env.BILLING_CURRENCY}