Authenticate Using GitHub on Android

GitHub is where over 65 million developers shape the future of software, together. Contribute to the open-source community, manage your Git repositories, review code like a pro, track bugs and features, power your CI/CD and DevOps workflows, and secure code before you commit it. So in this article, we are going to discuss how to authenticate using GitHub in your Android App with the help of Firebase User Authentication. 

Steps for Firebase user Authentication using GitHub

Step 1: 

Create a new project in android studio or open any existing project through with you want to authenticate a user by GitHub and add the firebase to that android application. Steps to add firebase in your application.

Step 2: 

Go to your firebase console, go to your application then navigate to project settings and add fingerprint-like SHA1 of your connected application. To find SHA1 go to Gradle (right side of android-studio window ) > your-application-name > Tasks > Android > signingReport (double click on it)

Note: Make sure to add google-services.json in your application, otherwise, download it from the project settings of the firebase console and add it to your application.

Step 3:

Go back to your application in the firebase console, navigate to Authentication (left panel of firebase) then go to Sign-in-method enable GitHub provider.

Enable GitHub

Require Client ID & Client secret

Now, we need Client ID and Client Secret. For this register your app as a developer application on GitHub and get your app’s OAuth 2.0 Client ID and Client Secret. To register your app, write the application name, enter the app’s website homepage URL (here I’m giving the same URL as in the Authorization callback URL), and provide the application description in brief.

Register an app on GitHub

Note: 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. 

Get your authorizable callback URL as shown in the image below.

Get your authorization callback URL

Click Register application. You will get your Client ID and Client secret, copy and paste them in the firebase console (under sign-in-method) and click the save button to enable GitHub.  

Step 4:

Come back to android studio. Add dependency for the Firebase Authentication Android library in your build.gradle (Module: your-application-name.app) by using the Firebase Android BoM .

dependencies {

   // Import the BoM for the Firebase platform

   implementation platform(‘com.google.firebase:firebase-bom:28.0.1’)

   // Declare the dependency for the Firebase Authentication library

   // When using the BoM, you don’t specify versions in Firebase library dependencies

   implementation ‘com.google.firebase:firebase-auth-ktx’

}

By using the Firebase Android BoM, your app will always use compatible versions of the Firebase Android libraries.

Step 5: Working with the MainActivity file

Navigate to the app > res > layout > activity_main.xml and add the below code to that file. Below is the code for the activity_main.xml file. 

XML

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:orientation="vertical"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">


        <EditText
            android:id="@+id/githubId"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="100dp"
            android:hint="Enter your email associated with github"
            android:padding="8dp"
            android:textAlignment="center"
            android:textColor="#118016" />

        <Button
            android:id="@+id/github_login_btn"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginStart="100dp"
            android:layout_marginTop="10dp"
            android:layout_marginEnd="100dp"
            android:layout_marginBottom="100dp"
            android:backgroundTint="#fff"
            android:drawableLeft="@drawable/github"
            android:drawablePadding="8dp"
            android:padding="8dp"
            android:text="@string/log_in_with_github"
            android:textAllCaps="false"
            android:textColor="#000" />
    </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

Go to the MainActivity.kt file and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.

Kotlin

import android.content.Intent
import android.os.Bundle
import android.text.TextUtils
import android.widget.Button
import android.widget.EditText
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.google.android.gms.tasks.OnFailureListener
import com.google.android.gms.tasks.OnSuccessListener
import com.google.android.gms.tasks.Task
import com.google.firebase.auth.AuthResult
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.FirebaseUser
import com.google.firebase.auth.OAuthProvider

class MainActivity : AppCompatActivity() {

    private lateinit var firebaseUser: FirebaseUser
    private lateinit var loginBtn: Button
    private lateinit var githubEdit: EditText

    // firebaseAuth variable to be initialized later
    private lateinit var auth: FirebaseAuth

    // an instance of an OAuthProvider using its Builder
      // with the provider ID github.com
    private val provider = OAuthProvider.newBuilder("github.com")

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        loginBtn = findViewById(R.id.github_login_btn)
        githubEdit = findViewById(R.id.githubId)

        // initializing auth
        auth = FirebaseAuth.getInstance()

          // Target specific email with login hint.
        provider.addCustomParameter("login", githubEdit.text.toString())

        // Request read access to a user's email addresses.
        // This must be preconfigured in the app's API permissions.
        val scopes: ArrayList<String?> = object : ArrayList<String?>() {
            init {
                add("user:email")
            }
        }
        provider.scopes = scopes

        // call signInWithGithubProvider() method
          // after clicking login Button
        loginBtn.setOnClickListener {
            if (TextUtils.isEmpty(githubEdit.text.toString())) {
                Toast.makeText(this, "Enter your github id", Toast.LENGTH_LONG).show()
            } else {
                signInWithGithubProvider()
            }
        }
    }

    // To check if there is a pending result, call pendingAuthResult
    private fun signInWithGithubProvider() {

        // There's something already here! Finish the sign-in for your user.
        val pendingResultTask: Task<AuthResult>? = auth.pendingAuthResult
        if (pendingResultTask != null) {
            pendingResultTask
                    .addOnSuccessListener {
                        // User is signed in.
                        Toast.makeText(this, "User exist", Toast.LENGTH_LONG).show()
                    }
                    .addOnFailureListener {
                        // Handle failure.
                        Toast.makeText(this, "Error : $it", Toast.LENGTH_LONG).show()
                    }
        } else {

            auth.startActivityForSignInWithProvider( /* activity= */this, provider.build())
                    .addOnSuccessListener(
                            OnSuccessListener<AuthResult?> {
                                // User is signed in.
                                // retrieve the current user
                                firebaseUser = auth.currentUser!!

                                // navigate to HomePageActivity after successful login
                                val intent = Intent(this, HomePageActivity::class.java)

                                  // send github user name from MainActivity to HomePageActivity
                                intent.putExtra("githubUserName", firebaseUser.displayName)
                                this.startActivity(intent)
                                Toast.makeText(this, "Login Successfully", Toast.LENGTH_LONG).show()

                            })
                    .addOnFailureListener(
                            OnFailureListener {
                                // Handle failure.
                                Toast.makeText(this, "Error : $it", Toast.LENGTH_LONG).show()
                            })
        }

    }
}

Step 6: Create a new Empty Activity 

Refer to this article Create New Activity in Android Studio and create an empty activity. Name the activity as HomePageActivity. Navigate to the app > res > layout > activity_home_page.xml and add the below code to that file. Below is the code for the activity_home_page.xml file. 

XML

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".HomePageActivity">

    <LinearLayout
        android:id="@+id/linearLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="10dp"
        android:layout_marginTop="10dp"
        android:layout_marginEnd="10dp"
        android:orientation="horizontal"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <TextView
            android:id="@+id/headerId"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:text="User Name :"
            android:textColor="#06590A"
            android:textSize="25sp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <TextView
            android:id="@+id/id"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="10dp"
            android:layout_marginTop="10dp"
            android:hint="github Id"
            android:textAlignment="center"
            android:textSize="25sp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

    </LinearLayout>

    <Button
        android:id="@+id/logOut"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="456dp"
        android:layout_marginBottom="20dp"
        android:gravity="center"
        android:text="Logout"
        android:textColor="#fff"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/linearLayout" />

</androidx.constraintlayout.widget.ConstraintLayout>

Go to the HomePageActivity.kt file and refer to the following code. Below is the code for the HomePageActivity.kt file. 

Kotlin

import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.TextView

class HomePageActivity : AppCompatActivity() {

    var userName = ""

    private lateinit var githubUserName: TextView
    private lateinit var logoutBtn: Button

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_home_page)

        githubUserName = findViewById(R.id.id)
        logoutBtn = findViewById(R.id.logOut)
        userName = intent.getStringExtra("githubUserName")!!
        githubUserName.text = userName

        logoutBtn.setOnClickListener {
            val intent = Intent(this, MainActivity::class.java)
            this.startActivity(intent)
        }
    }
}

Note: Don’t forget to Revoke all user tokens. This option will be shown when your application is ready and run once. Or may you see this option earlier?

Here is the final output.

Output: