Authenticate Using GitHub on Android

You can let your users authenticate with Firebase using their GitHub accounts by integrating GitHub authentication into your app.

Before you begin

If you haven't already, add Firebase to your Android project.
In your project-level build.gradle file, make sure to include Google's Maven repository in both your buildscript and allprojects sections.
Add the dependency for the Firebase Authentication Android library to your module (app-level) Gradle file (usually app/build.gradle):
```
implementation 'com.google.firebase:firebase-auth:18.0.0'
```
Register your app as a developer application on GitHub and get your app's OAuth 2.0 Client ID and Client Secret.
Enable GitHub authentication:
1. In the Firebase console, open the Auth section.
2. On the Sign in method tab, enable the GitHub sign-in method and specify the OAuth 2.0 Client ID and Client Secret you got from GitHub.
3. Then, make sure your Firebase OAuth redirect URI (e.g. my-app-12345.firebaseapp.com/__/auth/handler) is set as your Authorization callback URL in your app's settings page on your GitHub app's config.

Authenticate with Firebase

Integrate GitHub authentication into your app by following the developer's documentation. Use the web application flow, and set up an intent filter in your app to handle the OAuth 2.0 callback from GitHub. At the end of the GitHub sign-in flow, you will receive an OAuth 2.0 access token.

In your sign-in activity's onCreate method, get the shared instance of the FirebaseAuth object:

Java

private FirebaseAuth mAuth;
// ...
// Initialize Firebase Auth
mAuth = FirebaseAuth.getInstance();AnonymousAuthActivity.java

Kotlin

private lateinit var auth: FirebaseAuth
// ...
// Initialize Firebase Auth
auth = FirebaseAuth.getInstance()AnonymousAuthActivity.kt

When initializing your Activity, check to see if the user is currently signed in:

Java

@Override
public void onStart() {
    super.onStart();
    // Check if user is signed in (non-null) and update UI accordingly.
    FirebaseUser currentUser = mAuth.getCurrentUser();
    updateUI(currentUser);
}AnonymousAuthActivity.java

Kotlin

public override fun onStart() {
    super.onStart()
    // Check if user is signed in (non-null) and update UI accordingly.
    val currentUser = auth.currentUser
    updateUI(currentUser)
}AnonymousAuthActivity.kt

After a user successfully signs in with GitHub, exchange the OAuth 2.0 access token for a Firebase credential, and authenticate with Firebase using the Firebase credential:

Java

String token = "<GITHUB-ACCESS-TOKEN>";
AuthCredential credential = GithubAuthProvider.getCredential(token);
mAuth.signInWithCredential(credential)
        .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
            @Override
            public void onComplete(@NonNull Task<AuthResult> task) {
                Log.d(TAG, "signInWithCredential:onComplete:" + task.isSuccessful());

                // If sign in fails, display a message to the user. If sign in succeeds
                // the auth state listener will be notified and logic to handle the
                // signed in user can be handled in the listener.
                if (!task.isSuccessful()) {
                    Log.w(TAG, "signInWithCredential", task.getException());
                    Toast.makeText(MainActivity.this, "Authentication failed.",
                            Toast.LENGTH_SHORT).show();
                }

                // ...
            }
        });MainActivity.java

Kotlin

val token = "<GITHUB-ACCESS-TOKEN>"
val credential = GithubAuthProvider.getCredential(token)
mAuth.signInWithCredential(credential)
        .addOnCompleteListener(this) { task ->
            Log.d(TAG, "signInWithCredential:onComplete:" + task.isSuccessful)

            // If sign in fails, display a message to the user. If sign in succeeds
            // the auth state listener will be notified and logic to handle the
            // signed in user can be handled in the listener.
            if (!task.isSuccessful) {
                Log.w(TAG, "signInWithCredential", task.exception)
                Toast.makeText(baseContext, "Authentication failed.",
                        Toast.LENGTH_SHORT).show()
            }

            // ...
        }MainActivity.kt

If the call to signInWithCredential succeeds, you can use the getCurrentUser method to get the user's account data.

Next steps

After a user signs in for the first time, a new user account is created and linked to the credentials—that is, the user name and password, phone number, or auth provider information—the user signed in with. This new account is stored as part of your Firebase project, and can be used to identify a user across every app in your project, regardless of how the user signs in.

In your apps, you can get the user's basic profile information from the FirebaseUser object. See Manage Users.
In your Firebase Realtime Database and Cloud Storage Security Rules, you can get the signed-in user's unique user ID from the auth variable, and use it to control what data a user can access.

You can allow users to sign in to your app using multiple authentication providers by linking auth provider credentials to an existing user account.

To sign out a user, call signOut:

Java

FirebaseAuth.getInstance().signOut();MainActivity.java

Kotlin

FirebaseAuth.getInstance().signOut()MainActivity.kt