SunCertPathBuilderException when using Firebase

Question

I have a Java Rest API running with Jersey on a Glassfish server, and I use Firebase Auth to authenticate my users. So I use the Firebase Admin SDK to verify the token FirebaseAuth.getInstance().verifyIdToken(idToken)

But it throws the following error:

sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

I initialize my app correctly, by calling:

FirebaseOptions options = new FirebaseOptions.Builder().setCredentials(GoogleCredentials.fromStream(serviceAccountStream)).build();

With serviceAccountStream an InputStream to my service account JSON file.

Edit: I got the same problem with Firebase's auth emulator and other Firebase services such as Firestore, that's weird

Answer 1

The problem is coming from the old libraries you use. The following code works fine on SpringBoot 2.5 set up:

    try {
        InputStream serviceAccount credStream = getClass().getResourceAsStream(credsPath);

        FirebaseOptions options = new FirebaseOptions.Builder()
                .setCredentials(GoogleCredentials.fromStream(credStream))
                .setDatabaseUrl(databaseURL)
                .build();
        FirebaseApp.initializeApp(options);
    } catch (Exception e) {
        logger.error(e.getMessage());
    } finally {
        ...
    }

If you cannot upgrade the libraries, you need to add your server certificate into the trustStore. Please, look here for the steps: Java: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target