Secure API Calls with OAuth 2.0 Client Credentials

import requests
import os

# Environment variables for client credentials
CLIENT_ID = os.environ.get("OAUTH_CLIENT_ID")
CLIENT_SECRET = os.environ.get("OAUTH_CLIENT_SECRET")
TOKEN_URL = "https://api.example.com/oauth/token"
API_BASE_URL = "https://api.example.com/data"

def get_access_token():
    """
    Obtains an access token using the OAuth 2.0 Client Credentials flow.
    """
    if not CLIENT_ID or not CLIENT_SECRET:
        raise ValueError("OAUTH_CLIENT_ID and OAUTH_CLIENT_SECRET must be set as environment variables.")

    headers = {
        "Content-Type": "application/x-www-form-urlencoded"
    }
    data = {
        "grant_type": "client_credentials",
        "client_id": CLIENT_ID,
        "client_secret": CLIENT_SECRET
    }

    try:
        response = requests.post(TOKEN_URL, headers=headers, data=data)
        response.raise_for_status() # Raise an exception for HTTP errors
        token_data = response.json()
        return token_data.get("access_token")
    except requests.exceptions.RequestException as e:
        print(f"Error obtaining access token: {e}")
        return None

def call_protected_api(access_token):
    """
    Calls a protected API endpoint using the obtained access token.
    """
    if not access_token:
        print("No access token available to call the API.")
        return None

    headers = {
        "Authorization": f"Bearer {access_token}",
        "Accept": "application/json"
    }

    try:
        response = requests.get(f"{API_BASE_URL}/protected-resource", 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__":
    token = get_access_token()
    if token:
        print("Access token obtained successfully.")
        api_data = call_protected_api(token)
        if api_data:
            print("Protected API data:", api_data)
        else:
            print("Failed to retrieve data from protected API.")
    else:
        print("Failed to obtain access token.")