When I first built my CodePod app, I used Firebase Authentication to manage users and Firestore for storing their data. Everything worked fine until I started running into permission errors and authentication issues—especially after trying to add more advanced login features.
The Problems I Faced
- Firebase Permission Errors : My frontend was trying to access Firestore directly, but without a valid Firebase Auth session, I kept getting "Missing or insufficient permissions" errors.
- Auth0 Integration Issues : When I switched to Auth0 for authentication, the user object structure changed ( uid became sub ), which broke my existing code.
- Content Security Policy (CSP) Violations : Auth0's login popups and iframes were blocked by my server's CSP settings.
- Session Management : Auth0 cached login state, making it hard to switch accounts or test different users. ## How I Fixed It ### 1. Mapped Auth0 User to Firebase Format I updated my Auth context so that the Auth0 user object matched what my app expected from Firebase. This meant mapping user.sub to currentUser.uid and including other properties like email , displayName , and photoURL .
const currentUser = user ? {
uid: user.sub,
email: user.email,
displayName: user.name,
photoURL: user.picture,
emailVerified: user.email_verified
} : null;
2. Stopped Direct Firestore Access from the Frontend
Instead of letting the frontend talk directly to Firestore, I created backend API endpoints for user data. This way, the backend could use the Firebase Admin SDK to securely access Firestore, and the frontend just called the API.
// routes/users.js
router.get('/api/users/:id',
authenticateToken, async (req, res)
=> {
// ...fetch user from Firestore
using Admin SDK...
});
3. Fixed Content Security Policy (CSP) Settings
I updated my server's CSP headers to allow Auth0 domains in frame-src and connect-src , and changed the Cross-Origin-Opener-Policy to "unsafe-none" so Auth0 popups could communicate with my app.
app.use(helmet({
crossOriginOpenerPolicy: {
policy: "unsafe-none" },
contentSecurityPolicy: {
directives: {
frameSrc: [
"'self'",
"https://your-domain.auth0.
com"
],
connectSrc: [
"'self'",
"https://your-domain.auth0.
com"
]
}
}
}));
4. Improved Session Management
To make sure users could select their account and avoid auto-login, I used Auth0's prompt: "select_account" option.
What I Learned
- Migrating from Firebase Auth to Auth0 isn't just swapping libraries—you need to update user object mapping, backend APIs, and security policies.
- Backend APIs are safer and more flexible than direct database access from the frontend.
- Always check your CSP and CORS settings when integrating third-party authentication.
- Testing authentication flows with multiple accounts is much easier with proper session management
Top comments (2)
Using backend APIs for user data access enhances security and flexibility, especially when replacing direct database calls in serverless or microservices architectures.
if any suggestions please comment. Also check my profile for other cool stuff.