task-scheduler/app/main/__init__.py

from flask import Flask
from app.main.config import config_by_name
from app.main import extensions


def create_app(config_name):
    app = Flask(__name__)
    app.config.from_object(config_by_name[config_name])
    register_extensions(app)
    return app


def register_extensions(app):
    extensions.db.init_app(app)
    extensions.scheduler.init_app(app)
    extensions.scheduler.start()