__init__.py

import os
from flask import Flask

def create_app(test_config = None):
    # create and configure the app
    app = Flask(__name__, instance_relative_config=True)
    app.config.from_mapping(
        SECRET_KEY='dev',
        DATABASE=os.path.join(app.instance_path, 'monitor.sqlite')
    )

    if test_config is None:
        # load the instance config, if it exists, when not testing
        app.config.from_pyfile('config.py', silent=True)
    else:
        # load the test config if passed in
        app.config.from_mapping(test_config)

    #ensure the instance folder exists
    try:
        os.mkdir(app.instance_path)
    except OSError:
        pass

    # a simple page that says hello
    @app.route('/hello')
    def hello():
        return "hello world"

    from . import db
    db.init_app(app)

    from . import auth
    app.register_blueprint(auth.bp)

    from . import video
    app.register_blueprint(video.bp)
    app.add_url_rule('/', endpoint='video')

    from . import criminal
    app.register_blueprint(criminal.bp)

    from . import records_management
    app.register_blueprint(records_management.bp)
    #
    # from . import camera
    # app.register_blueprint(camera.bp)

    return app