OAuth 2.0 Client Credentials Flow (Python)

import requests
import os

# Configuration from environment variables for security
TOKEN_URL = os.getenv('OAUTH_TOKEN_URL', 'https://api.example.com/oauth/token')
CLIENT_ID = os.getenv('OAUTH_CLIENT_ID', 'your_client_id')
CLIENT_SECRET = os.getenv('OAUTH_CLIENT_SECRET', 'your_client_secret')
API_SCOPE = os.getenv('OAUTH_API_SCOPE', 'read write')

def get_oauth_token():
    """Fetches an access token using Client Credentials Grant."""
    headers = {
        'Content-Type': 'application/x-www-form-urlencoded'
    }
    payload = {
        'grant_type': 'client_credentials',
        'client_id': CLIENT_ID,
        'client_secret': CLIENT_SECRET,
        'scope': API_SCOPE
    }
    try:
        response = requests.post(TOKEN_URL, headers=headers, data=payload)
        response.raise_for_status() # Raises HTTPError for bad responses (4xx or 5xx)
        token_data = response.json()
        return token_data.get('access_token')
    except requests.exceptions.RequestException as e:
        print(f"Error fetching OAuth token: {e}")
        return None

def call_protected_api(access_token, api_url):
    """Calls a protected API endpoint with the obtained access token."""
    if not access_token:
        print("No access token available. Cannot call API.")
        return None
    
    headers = {
        'Authorization': f'Bearer {access_token}',
        'Content-Type': 'application/json'
    }
    try:
        response = requests.get(api_url, headers=headers)
        response.raise_for_status()
        return response.json()
    except requests.exceptions.RequestException as e:
        print(f"Error calling protected API: {e}")
        return None

if __name__ == '__main__':
    # Example usage
    token = get_oauth_token()
    if token:
        print(f"Obtained Access Token: {token[:30]}...")
        # Replace with your actual protected API endpoint
        PROTECTED_API_URL = os.getenv('PROTECTED_API_URL', 'https://api.example.com/data')
        api_response = call_protected_api(token, PROTECTED_API_URL)
        if api_response:
            print("Protected API Response:")
            print(api_response)
    else:
        print("Failed to obtain OAuth token.")