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For our new friends:

Logto is an Auth0 alternative designed for modern apps and SaaS products. It offers both Cloud and Open-source services to help you quickly launch your identity and management (IAM) system. Enjoy authentication, authorization, and multi-tenant management all in one.

We recommend starting with a free development tenant on Logto Cloud. This allows you to explore all the features easily.

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

Prerequisites

Create an application in Logto​

Logto is based on OpenID Connect (OIDC) authentication and OAuth 2.0 authorization. It supports federated identity management across multiple applications, commonly called Single Sign-On (SSO).

To create your Native app application, simply follow these steps:

  1. Open the Logto Console. In the "Get started" section, click the "View all" link to open the application frameworks list. Alternatively, you can navigate to Logto Console > Applications, and click the "Create application" button. Get started
  2. In the opening modal, click 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. Frameworks
  3. Enter the application name, e.g., "Bookstore," and click "Create application".

πŸŽ‰ 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 Android (Kotlin) / Android (Java) SDK​

tip:

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:

build.gradle.kts
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
}

Configure redirect URI​

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".

Redirect URI in Logto Console

Implement sign-in and sign-out​

note:

Before calling logtoClient.signIn, make sure you have correctly configured Redirect URI in Admin Console.

You can use logtoClient.signIn to sign in the user and logtoClient.signOut to sign out the user.

For example, in an Android app:

LogtoModelView.kt
//...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 call the signIn and signOut methods in your activity:

MainActivity.kt
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)
}

// Assume you have a button with id "sign_out_button" in your layout
val signOutButton = findViewById<Button>(R.id.sign_out_button)
signOutButton.setOnClickListener {
if (logtoViewModel.authenticated) { // Check if the user is authenticated
logtoViewModel.signOut()
}
}

// Observe the authentication status to update the UI
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
}
}

}
}

Checkpoint: Test your application​

Now, you can test your application:

  1. Run your application, you will see the sign-in button.
  2. Click the sign-in button, the SDK will init the sign-in process and redirect you to the Logto sign-in page.
  3. After you signed in, you will be redirected back to your application and see the sign-out button.
  4. Click the sign-out button to clear token storage and sign out.

Add Hugging Face connector​

To enable quick sign-in and improve user conversion, connect with Android (Kotlin) / Android (Java) as an identity provider. The Logto social connector helps you establish this connection in minutes by allowing several parameter inputs.

To add a social connector, simply follow these steps:

  1. Navigate to Console > Connectors > Social Connectors.
  2. Click "Add social connector" and select "Hugging Face".
  3. Follow the README guide and complete required fields and customize settings.

Connector tab

note:

If you are following the in-place Connector guide, you can skip the next section.

Set up Hugging Face OAuth app​

Sign in with Hugging Face account​

Go to the Hugging Face website and sign in with your Hugging Face account. You may register a new account if you don't have one.

Create an OAuth app in the Hugging Face​

Follow the Creating an oauth app guide, and register a new application.

In the creation process, you will need to provide the following information:

  • Application Name: The name of your application.
  • Homepage URL: The URL of your application's homepage or landing page.
  • Logo URL: The URL of your application's logo.
  • Scopes: The scopes allowed for the OAuth app. For Hugging Face connector, usually use profile to get the user's profile information and email to get the user's email address. Ensure these scopes are allowed in your Hugging Face OAuth app if you want to use them.
  • Redirect URI: The URL to redirect the user to after they have authenticated. You can find the redirect URI in the Logto Admin Console when you're creating a Hugging Face connector or in the created Hugging Face connector details page.

Managing Hugging Face OAuth apps​

Go to the Connected Applications page, you can add, edit or delete existing OAuth apps. You can also find Client ID and generate App secrets in corresponding OAuth app settings pages.

Configure your connector​

Fill out the clientId and clientSecret field with Client ID and App Secret you've got from OAuth app detail pages mentioned in the previous section.

scope is a space-delimited list of Hugging Face supported scopes. If not provided, scope defaults to be profile. For Hugging Face connector, the scope you may want to use is profile and email. profile scope is required to get the user's profile information, and email scope is required to get the user's email address. Ensure you have allowed these scopes in your Hugging Face OAuth app (configured in Create an OAuth app in the Hugging Face section).

Config types​

NameType
clientIdstring
clientSecretstring
scopestring

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 Hugging Face connector should be available now.

Enable Hugging Face connector in Sign-in Experience​

Once you create a social connector successfully, you can enable it as a "Continue with Hugging Face" button in Sign-in Experience.

  1. Navigate to Console > Sign-in experience > Sign-up and sign-in.
  2. (Optional) Choose "Not applicable" for sign-up identifier if you need social login only.
  3. Add configured Hugging Face connector to the "Social sign-in" section.

Sign-in Experience tab

Testing and Validation​

Return to your Android (Kotlin / Java) app. You should now be able to sign in with Hugging Face. Enjoy!

Further readings​

End-user flows: Logto provides a out-of-the-box authentication flows including MFA and enterprise SSO, along with powerful APIs for flexible implementation of account settings, security verification, and multi-tenant experience.

Authorization: Authorization defines the actions a user can do or resources they can access after being authenticated. Explore how to protect your API for native and single-page applications and implement Role-based Access Control (RBAC).

Organizations: Particularly effective in multi-tenant SaaS and B2B apps, the organization feature enable tenant creation, member management, organization-level RBAC, and just-in-time-provisioning.

Customer IAM series Our serial blog posts about Customer (or Consumer) Identity and Access Management, from 101 to advanced topics and beyond.