keycloak_wrapper

Keycloak Wrapper

Integrate Keycloak Single Sign-On (SSO) authentication into your Flutter apps seamlessly using this package. Tokens are automatically managed under the hood and are easily accessible. A user authentication state stream is provided for your app to listen to in order to stay in sync with authentication status changes.

Getting Started

For end-user authentication and authorization, this package integrates with the AppAuth SDK to establish connections using OAuth 2.0 and OpenID Connect (OIDC). This integration allows users to securely log in and access protected resources, such as APIs or user data from third-party providers. For token security, the flutter_secure_storage package is used to securely store all tokens in the Keychain for iOS and Keystore for Android.

[!NOTE]

• AndroidX is required for this package. Starting from Flutter v1.12.13, newly created projects enable AndroidX by default. If your project was created before this Flutter version, please migrate it before using this package. You can follow this migration guide provided by the Flutter team.

• Starting with Android API 28 and iOS 9, insecure HTTP connections are disabled by default. Check out this guide if you want to allow cleartext connections for your build. However, it is not recommended for release builds. Please use secure connections whenever possible.

Keycloak

Go to your Keycloak Administration Console and select your Client ID. In the access settings section, add <bundle_identifier>:/* as a valid redirect URI, and do the same for the valid post logout redirect URI. Ensure your bundle identifier does not contain any characters that are not allowed in a hostname, such as spaces or underscores.

Android

Specify the custom scheme in your Android app’s build.gradle file. There should be a section similar to the following; replace <package_name> with your desired value:

android {
    ...
    defaultConfig {
        ...
        manifestPlaceholders += [
                'appAuthRedirectScheme': '<package_name>'
        ]
    }
}

Ensure that <package_name> is all lowercase, as there have been reports of issues with redirects if there are any capital letters. Note that the += operation is used on manifestPlaceholders instead of =. This is intentional and required, as newer versions of the Flutter SDK have made changes under the hood to handle multidex. Using = instead of += can lead to errors like the following:

Attribute application@name at AndroidManifest.xml:5:9-42 requires a placeholder substitution but no value for <applicationName> is provided.

If you see this error, update your build.gradle to use += instead.

[!WARNING]

• Starting from Flutter v3.22.0, newly created projects will disallow task affinity by default to prevent the StrandHogg attack. However, these changes have broken the package, as users will no longer be able to redirect back to the app after login. Currently, the only way to fix this issue is to remove android:taskAffinity="" from your AndroidManifest.xml file.

iOS/macOS

Specify the custom scheme in your iOS/macOS app’s Info.plist file. There should be a section similar to the following; replace <bundle_identifier> with your desired value:

<key>CFBundleURLTypes</key>
<array>
    <dict>
        <key>CFBundleTypeRole</key>
        <string>Editor</string>
        <key>CFBundleURLSchemes</key>
        <array>
            <string><bundle_identifier></string>
        </array>
    </dict>
</array>

Usage

First, create an instance of the plugin somewhere in your code.

final keycloakWrapper = KeycloakWrapper();

Next, initialize the plugin with your own configuration values within the main() method to set up the user authentication stream as soon as your app launches.

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  keycloakWrapper.initialize(
    config: KeycloakConfig(
      bundleIdentifier: '<bundle_identifier>',
      clientId: '<client_id>',
      frontendUrl: '<frontend_url>',
      realm: '<realm>',
    ),
  );
  ...
  runApp(const MyApp());
}

To listen to the user authentication state stream, create a StreamBuilder widget that listens to keycloakWrapper.authenticationStream. Navigate the user to the login screen when the stream returns false, and redirect to the home screen when login is successful. Set the initial value of the StreamBuilder to false to ensure the stream never returns null.

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) => MaterialApp(
        home: StreamBuilder<bool>(
            initialData: false,
            stream: keycloakWrapper.authenticationStream,
            builder: (context, snapshot) =>
                snapshot.data! ? const HomeScreen() : const LoginScreen()),
      );
}

Then create a button somewhere in your login screen and use the following method to initiate the login process:

Future<void> login() async {
  final isLoggedIn = await keycloakWrapper.login();
}

Once logged in, you can retrieve the user's information and tokens as shown below:

// Retrieve user's information.
final user = await keycloakWrapper.getUserInfo();

final name = user?['name'];
final email = user?['email'];

// Retrieve tokens.
final accessToken = keycloakWrapper.accessToken;
final idToken = keycloakWrapper.idToken;
final refreshToken = keycloakWrapper.refreshToken;

To log out, simply call the following method. Make sure to pop all stacked screens, if there are any.

Future<void> logout() async {
  final isLoggedOut = await keycloakWrapper.logout();
}

By default, all errors and exceptions are handled by the onError method of the KeycloakWrapper class, which prints the error directly to the console. You can customize this behavior if you want to display a custom message to users when specific errors, such as authorization failures, occur. Below is an example of how you can override the method and handle errors and exceptions in your own way:

keycloakWrapper.onError = (message, error, stackTrace) {
  // Add your custom error handling logic here.
};

For further customization, you can customize the optional parameters available inside the configuration. All shown above are only the mandatory ones. You can refer to the example to see how this package works in a real-life app.

Contribute

Contributions are welcome! However, please make sure to follow the guidelines below to avoid unnecessary waste of time and resources.

• Found a bug?
  Ensure the bug has not already been reported by searching on GitHub under Issues. If you can't find an open issue addressing the problem, open a new one. Be sure to include a title, a clear description, as much relevant information as possible, and a code sample or an executable test case demonstrating the expected behavior that is not occurring.

• Need some help?
  Feel free to open a new discussion on GitHub if you need help from the community. I'll try my best to help you as soon as possible. If you want to make any feature requests, you can use the same platform for us to discuss your idea further.

• Want to contribute?
  Since I am the only maintainer of this package, frequent bug fixes or updates might not be feasible. Therefore, any pull requests are greatly appreciated! Please ensure that the PR description clearly outlines both the problem and the proposed solution. If applicable, include the relevant issue number in the description.

Thanks! ❤️