How to build Google sign-in with Android and Logto

November 22, 2024 · 2 min read

The better identity infrastructure for developers

For our new friends

Every app needs authentication and authorization. Logto is an Auth0 alternative designed for modern apps and SaaS products.

In this article, we will go through the steps to quickly build the Google sign-in experience (user authentication) with Android and Logto.

Prerequisites

A running Logto instance. Check out the get started page if you don't have one.
Basic knowledge of Android.
A usable Google account.

Create an application in Logto

In you browser, open a new tab and enter the link of Logto Admin Console.

Get Started

Once the page is loaded, in the "Get Started" section click the View all link to open the application framework list page.

Choose your application type

Framework List

In the opening modal, scroll to the "Native app" section or filter all the available " Native app" frameworks using the quick filter checkboxes on the left.

Click the "Android (Kotlin)" / "Android (Java)" framework card to start creating your application.

Enter application name

Enter the application name, e.g., "Bookstore," and click "Create application."

🎉 Ta-da! You just created your first application in Logto. You'll see a congrats page which includes a detailed integration guide. Follow the guide to see what the experience will be in your application.

Integrate Logto SDK

tip

The example is based on View system and View Model, but the concepts are the same when using Jetpack Compose.
The example is written in Kotlin, but the concepts are the same for Java.
Both Kotlin and Java sample projects are available on our SDK repository.
The tutorial video is available on our YouTube channel.

Installation

note

The minimum supported Android API level of Logto Android SDK is level 24.

Before you install Logto Android SDK, ensure mavenCentral() is added to your repository configuration in the Gradle project build file:

settings.gradle.kts
dependencyResolutionManagement {
  repositories {
    mavenCentral()
  }
}

Add Logto Android SDK to your dependencies:

Kotlin
Groovy

build.gradle.kts
dependencies {
  implementation("io.logto.sdk:android:1.1.3")
}

build.gradle
dependencies {
  implementation 'io.logto.sdk:android:1.1.3'
}

Since the SDK needs internet access, you need to add the following permission to your AndroidManifest.xml file:

AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools">

  <!-- add internet permission -->
  <uses-permission android:name="android.permission.INTERNET" />

  <!-- other configurations... -->
</manifest>

Init LogtoClient

Create a LogtoViewModel.kt and init LogtoClient in this view model:

LogtoViewModel.kt
//...with other imports
import io.logto.sdk.android.LogtoClient
import io.logto.sdk.android.type.LogtoConfig

class LogtoViewModel(application: Application) : AndroidViewModel(application) {
    private val logtoConfig = LogtoConfig(
          endpoint = "<your-logto-endpoint>",
          appId = "<your-app-id>",
          scopes = null,
          resources = null,
          usingPersistStorage = true,
    )

    private val logtoClient = LogtoClient(logtoConfig, application)

    companion object {
        val Factory: ViewModelProvider.Factory = object : ViewModelProvider.Factory {
            @Suppress("UNCHECKED_CAST")
            override fun <T : ViewModel> create(
                modelClass: Class<T>,
                extras: CreationExtras
            ): T {
                // Get the Application object from extras
                val application = checkNotNull(extras[APPLICATION_KEY])
                return LogtoViewModel(application) as T
            }
        }
    }
}

then, create a LogtoViewModel for your MainActivity.kt:

MainActivity.kt
//...with other imports
class MainActivity : AppCompatActivity() {
    private val logtoViewModel: LogtoViewModel by viewModels { LogtoViewModel.Factory }
    //...other codes
}

Before starting, you need to add a redirect URI in the Admin Console for your application.

In Android, the redirect URI follows the pattern: $(LOGTO_REDIRECT_SCHEME)://$(YOUR_APP_PACKAGE)/callback:

The LOGTO_REDIRECT_SCHEME should be a custom scheme in the reverse domain format.
The YOUR_APP_PACKAGE is your app package name.

Assuming you treat io.logto.android as the custom LOGTO_REDIRECT_SCHEME, and io.logto.sample is your app package name, the Redirect URI should be io.logto.android://io.logto.sample/callback.

Let's switch to the Application details page of Logto Console. Add a Redirect URI io.logto.android://io.logto.sample/callback and click "Save changes".

After the redirect URI is configured, we add a signIn method to your LogtoViewModel.kt, which will call logtoClient.signIn API to invoke the Logto sign-in page:

//...with other imports
class LogtoViewModel(application: Application) : AndroidViewModel(application) {
    // ...other codes
    fun signIn(context: Activity) {
        logtoClient.signIn(context, "io.logto.android://io.logto.sample/callback") { logtoException ->
            logtoException?.let { println(it) }
        }
    }
}

Now setup on-click listener for the sign-in button in your MainActivity.kt to call the signIn method:

//...with other imports
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        //...other codes

        // Assume you have a button with id `sign_in_button` in your layout
        val signInButton = findViewById<Button>(R.id.sign_in_button)
        signInButton.setOnClickListener {
            logtoViewModel.signIn(this)
        }
    }
}

When you click the button, the Logto SDK will navigate to the Logto sign-in page.

Implement sign-out

Similar to sign-in, we add a signOut method to LogtoViewModel.kt to call logtoClient.signOut API:

//...with other imports
class LogtoViewModel(application: Application) : AndroidViewModel(application) {
    // ...other codes
    fun signOut() {
        logtoClient.signOut { logtoException ->
            logtoException?.let { println(it) }
        }
    }
}

After you signed out, the Logto SDK will clear all local credentials even though Logto exceptions occurred when calling logtoClient.signOut API.

Then, we can add a button to call the signOut method in MainActivity.kt:

//...with other imports
class MainActivity : AppCompatActivity() {
    //...other codes
    override fun onCreate(savedInstanceState: Bundle?) {
        //...other codes
        //...sign-in button codes

        // Assume you have a button with id `sign_out_button` in your layout
        val signOutButton = findViewById<Button>(R.id.sign_out_button)
        signOutButton.setOnClickListener {
            logtoViewModel.signOut()
        }
    }
}

Handle authentication status

In Logto SDK, we can use logtoClient.isAuthenticated to check the authentication status, if the user is signed in, the value will be true, otherwise, the value will be false.

Now, let's add a live data to LogtoViewModel.kt to observe the authentication status, and update the status when the user signed in or signed out:

//...with other imports
class LogtoViewModel(application: Application) : AndroidViewModel(application) {
    // ...other codes

    // Add a live data to observe the authentication status
    private val _authenticated = MutableLiveData(logtoClient.isAuthenticated)
    val authenticated: LiveData<Boolean>
        get() = _authenticated

    fun signIn(context: Activity) {
        logtoClient.signIn(context, "io.logto.android://io.logto.sample/callback") { logtoException ->
            logtoException?.let { println(it) }
            // Update the live data
            _authenticated.postValue(logtoClient.isAuthenticated)
        }
    }

    fun signOut() {
        logtoClient.signOut { logtoException ->
            logtoException?.let { println(it) }
            // Update the live data
            _authenticated.postValue(logtoClient.isAuthenticated)
        }
    }
}

Then, we observe the authenticated live data in MainActivity.kt, when the user is signed in, we hide the sign-in button and show the sign-out button and vice versa:

//...with other imports
class MainActivity : AppCompatActivity() {
    //...other codes
    override fun onCreate(savedInstanceState: Bundle?) {
        //...other codes
        val signInButton = findViewById<Button>(R.id.sign_in_button)
        val signOutButton = findViewById<Button>(R.id.sign_out_button)
        // ...handle button click codes

        // Observe the authentication status
        logtoViewModel.authenticated.observe(this) { authenticated ->
            if (authenticated) {
                // The user is authenticated
                signInButton.visibility = View.GONE
                signOutButton.visibility = View.VISIBLE
            } else {
                // The user is not authenticated
                signInButton.visibility = View.VISIBLE
                signOutButton.visibility = View.GONE
            }
        }
    }
}

Test your integration

Open your Android app to test if the integration works. When you click the "Sign In" button, the page should be redirected to a Logto sign-in page, and you should be able to create a new account by entering username and password and complete the sign-in process.

Add Google connector

To add a social connector, go to the "Connector" tab in the Admin Console, then click on "Social connectors". From there, click "Add social connector".

In the openning modal, select "Google" and click "Next".

On the next page, you will see a two-column layout with the README content on the left and configuration on the right.

Feel free to follow the README file in place or read the following section to complete the configuration process. If you follow the in-place guide, you can skip the next section.

Set up Google OAuth app

Set up a project in the Google API Console

Visit the Google API Console and sign in with your Google account.
Click the Select a project button on the top menu bar, and click the New Project button to create a project.
In your newly created project, click the APIs & Services to enter the APIs & Services menu.

On the left APIs & Services menu, click the OAuth consent screen button.
Choose the User Type you want, and click the Create button. (Note: If you select External as your User Type, you will need to add test users later.)

Now you will be on the Edit app registration page.

Follow the instructions to fill out the OAuth consent screen form.
Click SAVE AND CONTINUE to continue.

Config scopes

Click ADD OR REMOVE SCOPES and select ../auth/userinfo.email, ../auth/userinfo.profile and openid in the popup drawer, and click UPDATE to finish.
Fill out the form as you need.
Click SAVE AND CONTINUE to continue.

Add test users (External user type only)

Click ADD USERS and add test users to allow these users to access your application while testing.
Click SAVE AND CONTINUE to continue.

Now you should have the Google OAuth 2.0 consent screen configured.

Obtain OAuth 2.0 credentials

On the left APIs & Services menu, click the Credentials button.
On the Credentials page, click the + CREATE CREDENTIALS button on the top menu bar, and select OAuth client ID.
On the Create OAuth client ID page, select Web application as the application type.
Fill out the basic information for your application.
Click + Add URI to add an authorized domain to the Authorized JavaScript origins section. This is the domain that your logto authorization page will be served from. In our case, this will be ${your_logto_origin}. e.g.https://logto.dev.
Click + Add URI in the **Authorized redirect URIs** section to set up the **Authorized redirect URIs**, which redirect the user to the application after logging in. In our case, this will be ${your_logto_endpoint}/callback/${connector_id}. e.g. https://logto.dev/callback/${connector_id}. The connector_id can be found on the top bar of the Logto Admin Console connector details page.
Click Create to finish and then you will get the Client ID and Client Secret.

References

Config types

Name	Type
clientId	string
clientSecret	string

Google developer docs

Google Identity: Setting up OAuth 2.0

Save your configuration

Double check you have filled out necessary values in the Logto connector configuration area. Click "Save and Done" (or "Save changes") and the Google connector should be available now.

Switch to the "Sign-in experience" tab, then click the "Sign-up and sign-in" tab.

note

If it's the first time you enter the tab, you will see a quick introduction about Sign-in Experience and its basic configuration.

Sign-in Experience tab

Select "None" for the "Sign-up identifier" to provide minimum sign-up effort for Google sign-in, which may increase your conversion rate.

In the "Social sign-in" section, add "Add Social Connector" and choose "Google". Then you should be able to see a button with text "Continue with Google" in the preview section.

Save changes

Finally, click "Save changes" on the bottom right corner.

Testing and Validation

Return to your Android app. You should now be able to sign in with Google. Enjoy!

Create an application in Logto​

Choose your application type​

Enter application name​

Integrate Logto SDK​

Installation​

Init LogtoClient​

Implement sign-in​

Implement sign-out​

Handle authentication status​

Add Google connector​

Set up Google OAuth app​

Set up a project in the Google API Console​

Configure your consent screen​

Config OAuth consent screen​

Config scopes​

Add test users (External user type only)​

Obtain OAuth 2.0 credentials​

References​

Config types​

Google developer docs​

Save your configuration​

Enable Google connector in Sign-in Experience​

Testing and Validation​

Further readings​