Authorization and Authentication in Flask

Authorization and Authentication in Flask

In Flask, authorization and authentication can be implemented using various libraries and techniques. Here are some common approaches:

• Flask-Login: A widely used library for user session management and authentication.
• Flask-Security: An extension that provides authentication, authorization, and role-based access control.
• JWT (JSON Web Tokens): A popular method for authentication by generating and verifying tokens.
• OAuth: A protocol used for authorization and authentication with third-party applications.
• Basic Authentication: A simple authentication method that sends credentials with each request.
• Token-based Authentication: A method where a token is generated and used for subsequent requests.

Introduction

Authorization and authentication in Flask are important for access control and user identity verification. Extensions like Flask-Login, Flask-Security, or Flask-Principal are used to integrate these systems with Flask.

Summary:

• Authorization and authentication are two important concepts in web application security.
• Authorization involves defining and enforcing access rules for different parts of the web application.
• Authentication ensures that authenticated users have the necessary roles or permissions.

Authentication

• Authentication involves identifying a user based on their credentials.
• Flask does not have built-in authentication mechanisms but allows for easy integration.

Code block:

User Model:
from werkzeug.security import generate_password_hash, check_password_hash
from flask_sqlalchemy import SQLAlchemy

db = SQLAlchemy()

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True, nullable=False)
    password_hash = db.Column(db.String(120))

    def set_password(self, password):
        self.password_hash = generate_password_hash(password)

    def check_password(self, password):
        return check_password_hash(self.password_hash, password)

Code Sample:

from flask_login import LoginManager, login_user, logout_user, login_required

login_manager = LoginManager()
login_manager.init_app(app)

@app.route('/login', methods=['GET', 'POST'])
def login():
    # Code to verify the user credentials and log the user in
    user = User.query.filter_by(username=form.username.data).first()
    if user is not None and user.check_password(form.password.data):
        login_user(user)
        return redirect(url_for('index'))

Python Code: Authorization

from flask_login import current_user
from functools import wraps

def role_required(role):
    def decorator(fn):
        @wraps(fn)
        def wrapper(*args, **kwargs):
            if not current_user.role == role:
                return abort(401)  # Unauthorized
            return fn(*args, **kwargs)
        return wrapper
    return decorator

@app.route('/admin')
@role_required('admin')
def admin_page():
    return render_template('admin.html')

Conclusion

• Flask's authentication and authorization mechanisms use decorators to control access to routes.
• Extensions for authentication and authorization seamlessly integrate with Flask.

Next Steps

• Explore how to implement equivalent authorization and authentication in FastAPI.