Deescovery

Deescovery is a Python package to find and initialize modules of your Python projects on startup.

Find and register blueprints in a Flask project.
Automatically initialize Flask extensions.
Find all SQLAlchemy models to make alembic happy.
Find all FastAPI endpoints.
Collect all Celery tasks.

Initially designed to initialize Flask applications, it was made generic enough to work with any micro-framework or no framework at all.

Micro-framework initialization problem

Micro-framework-based projects are clean while they're small. Every micro-framework codebase I've seen, has a mess in the project initialization. With time, create_app() becomes filled with ad-hoc settings, imports-within-functions, and plug-in initializations.

The Application Factory Pattern, proposed, for example, in the official Flask documentation, and the Flask Mega-Tutorial, legitimize this approach.

The nature of create_app() leaves no place for the open-closed principle. We update this module every time we add a new plug-in, a new blueprint, or a new package.

# myproject/__init__.py

def create_app(config_class=Config):
    app = Flask(__name__)
    app.config.from_object(config_class)

    db.init_app(app)
    migrate.init_app(app, db)
    login.init_app(app)
    mail.init_app(app)
    bootstrap.init_app(app)
    moment.init_app(app)
    babel.init_app(app)

    from myproject.errors import bp as errors_bp
    app.register_blueprint(errors_bp)

    from myproject.auth import bp as auth_bp
    app.register_blueprint(auth_bp, url_prefix='/auth')

    return app

A common Flask application. The code is based on the Flask Mega-Tutorial.

With deescovery, you can make the same code shorter, and remove the dependencies from implementation details.

# file: myproject/app.py
from flask import Flask
from deescovery import discover
from deescovery.flask import get_flask_rules


def create_app():
    flask_app = Flask(__name__)
    flask_app.config.from_object("myproject.config")
    discover("myproject", get_flask_rules("myproject", flask_app))
    return flask_app