Connect user to Firebase from front and back

Question

Here is my case :

• I have a front-end (AngularJS) with a connection to Firebase, and I user the firebase auth to authenticate users.
• For some special action (for example some time I need to send an email to the user), I have to call a webservice (NodeJs), which query Firebase, using firebase-admin package
• Currently this webservice isn't protected by authentication

So my question is how can I handle front and back user authentication with Firebase ?

How can I get the Firebase auth cookie then send it to my webservice to auth my user ?

Answer 1

Firebase provides some documentation on how to verify ID tokens. To retrieve the ID token within your client-side Angular code, you can do this:

firebase.auth().currentUser.getToken(/* forceRefresh */ true).then(function(idToken) {
  // Send token to your backend via HTTPS
  // ...
}).catch(function(error) {
  // Handle error
});

And to verify the idToken on the server:

// idToken comes from the client app (shown above)
admin.auth().verifyIdToken(idToken)
  .then(function(decodedToken) {
    var uid = decodedToken.uid;
    // ...
  }).catch(function(error) {
    // Handle error
  });