OAuth2 overview in Flask - Mini Project: Build & Apply

OAuth2 Overview with Flask

📖 Scenario: You are building a simple Flask web app that uses OAuth2 to let users log in with a third-party service.This project will guide you through setting up the basic OAuth2 flow in Flask.

🎯 Goal: Create a Flask app that sets up OAuth2 client configuration, defines a login route to start OAuth2 authorization, and a callback route to handle the OAuth2 response.

📋 What You'll Learn

Create a dictionary called oauth_config with OAuth2 client details

Create a variable called redirect_uri with the callback URL

Use requests_oauthlib.OAuth2Session to create an OAuth2 session with the client ID and redirect URI

Define Flask routes /login and /callback to handle OAuth2 authorization and response

💡 Why This Matters

🌍 Real World

OAuth2 is widely used to let users log in to apps using accounts from Google, Facebook, GitHub, and many other providers without sharing passwords.

💼 Career

Understanding OAuth2 and how to implement it in web frameworks like Flask is essential for building secure, user-friendly authentication in modern web applications.

1

Set up OAuth2 client configuration

Create a dictionary called oauth_config with these exact keys and values: 'client_id' set to 'your_client_id', 'client_secret' set to 'your_client_secret', 'authorization_base_url' set to 'https://provider.com/oauth2/auth', and 'token_url' set to 'https://provider.com/oauth2/token'.

Flask

# Your code here

Need a hint?

Use a Python dictionary with the exact keys and values given.

2

Define the redirect URI

Create a variable called redirect_uri and set it to the string 'http://localhost:5000/callback'.

Flask

oauth_config = {
    'client_id': 'your_client_id',
    'client_secret': 'your_client_secret',
    'authorization_base_url': 'https://provider.com/oauth2/auth',
    'token_url': 'https://provider.com/oauth2/token'
}
# Your code here

Need a hint?

Set the redirect URI exactly as shown.

3

Create OAuth2 session

Import OAuth2Session from requests_oauthlib. Then create a variable called oauth by calling OAuth2Session with oauth_config['client_id'] and redirect_uri=redirect_uri.

Flask

oauth_config = {
    'client_id': 'your_client_id',
    'client_secret': 'your_client_secret',
    'authorization_base_url': 'https://provider.com/oauth2/auth',
    'token_url': 'https://provider.com/oauth2/token'
}

redirect_uri = 'http://localhost:5000/callback'

# Your code here

Need a hint?

Remember to import OAuth2Session before using it.

4

Define Flask routes for login and callback

Import Flask, redirect, and request from flask. Create a Flask app called app. Define a route /login that uses oauth.authorization_url with oauth_config['authorization_base_url'] to get the authorization URL and state, then redirects the user to the authorization URL. Define a route /callback that fetches the token using oauth.fetch_token with oauth_config['token_url'], client_secret=oauth_config['client_secret'], and authorization_response=request.url. Return a simple string 'Login successful' in the callback route.

Flask

from requests_oauthlib import OAuth2Session

oauth_config = {
    'client_id': 'your_client_id',
    'client_secret': 'your_client_secret',
    'authorization_base_url': 'https://provider.com/oauth2/auth',
    'token_url': 'https://provider.com/oauth2/token'
}

redirect_uri = 'http://localhost:5000/callback'

oauth = OAuth2Session(oauth_config['client_id'], redirect_uri=redirect_uri)

# Your code here

Need a hint?

Define the Flask app and routes exactly as described to handle OAuth2 login and callback.