Vaadin + Firebase Auth example

A trivial example to use Firebase Authentication with a Vaadin application. The app is built based on start.vaadin.com template, with Spring Security setup enabled, but instead of storing users in local JPA backend, Firebase Authentication is used.

This example uses the "web" library to create the access token on the browser side and then shares that with the Vaadin application. An alternative approach would be to implement this completely on the server side by doing to the authentication request as described in this SoF response or by checking if the official Android library could be used.

Things to check out in this example.

• FirebaseService class. A class that initializes Firebase server side API, populates demo data if needed, and validates the token coming from client. and transforms into Authentication object for Spring Security.
• LoginView and its client side code in frontend/login.ts. This uses Vaadin Login element (could just use simple inputs as well) and Firebase JS modules to login. The token is then sent to server, validated and stores an Authentication based on the token details in Spring Security context (saved further in Java session).
• Adapted Spring Security configuartion in the security package.

Improvements needed for larger app

• Currently the example doesn't support roles, but those should be rather easy to implement with "custom claims".
• Session persistency. Currently, the token passed to server side will probably become invalid even if user Vaadin session is active. Should timely pass the refreshed token to the server side. Service worker appraoch could be used. Or just fetching the refreshed token asynchronously when the session should be verified.

Running the application

To run the example yourself, you'll need to create a Firebase Project and enable Firebase Authentication (refer to their docs). The GOOGLE_APPLICATION_CREDENTIALS environment variable needs to contain the path to your app credentials (or change the behaviour in FirebaseService) and you need to replace the Web/JS firebaseConfig with your Firebase web config in login.ts file.

Useful links

• Read the documentation at vaadin.com/docs.