Creating the Flask application

Let's go ahead and create the Flask application in a new app.py file:

app = Flask(__name__)

Since our application will use various forms and POST variables, we need to add Cross-Site Request Forgery (CSRF) protection:

csrf = CSRFProtect(app)

To use the Flask-login plugin, we also need to define a SECRET variable and instantiate the login manager:

app.config['SECRET_KEY'] = "THE SECRET"

login_manager = Flask_login.LoginManager()
login_manager.init_app(app)

With that, our Flask app has been created and we can run it with the following code:

Flask run

However, we have not created any routes yet, so for now, all our URLs will result in a 404, Not found error. We will add the /login route in the following paragraphs.