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Secure Java Spring Boot apps using Azure Active Directory B2C

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This article demonstrates a Java Spring Boot web app that signs in users on your Azure Active Directory B2C tenant using the Azure AD B2C Spring Boot Starter client library for Java. It uses the OpenID Connect protocol.

The following diagram shows the topology of the app:

Diagram that shows the topology of the app.

The client app uses the Azure AD B2C Spring Boot Starter client library for Java to sign in a user and obtain an ID token from Azure AD B2C. The ID token proves that the user is authenticated with Azure AD B2C and enables the user to access protected routes.

Prerequisites

Recommendations

  • Some familiarity with the Spring Framework
  • Some familiarity with Linux/OSX terminal or Windows PowerShell
  • jwt.ms for inspecting your tokens.
  • Fiddler for monitoring your network activity and troubleshooting.
  • Follow the Microsoft Entra ID Blog to stay up-to-date with the latest developments.

Set up the sample

The following sections show you how to set up the sample application.

Clone or download the sample repository

To clone the sample, open a Bash window and use the following command:

git clone https://github.com/Azure-Samples/ms-identity-java-spring-tutorial.git
cd ms-identity-java-spring-tutorial
cd 1-Authentication/sign-in-b2c

Alternatively, navigate to the ms-identity-java-spring-tutorial repository, then download it as a .zip file and extract it to your hard drive.

Important

To avoid file path length limitations on Windows, clone or extract the repository into a directory near the root of your hard drive.

This sample comes with a preregistered application for demo purposes. If you'd like to use your own Azure AD B2C tenant and application, register and configure the application in the Azure portal. For more information, see the Register the app section. Otherwise, continue with the steps in the Run the sample section.

Choose the Azure AD B2C tenant where you want to create your applications

To choose your tenant, use the following steps:

  1. Sign in to the Azure portal.

  2. If your account is present in more than one Azure AD B2C tenant, select your profile in the corner of the Azure portal, and then select Switch directory to change your session to the desired Azure AD B2C tenant.

Create user flows and custom policies

To create common user flows like sign-up, sign-in, profile edit, and password reset, see Tutorial: Create user flows in Azure Active Directory B2C.

You should consider creating custom policies in Azure Active Directory B2C as well. However, this task is beyond the scope of this tutorial. For more information, see Azure AD B2C custom policy overview.

Add external identity providers

See Tutorial: Add identity providers to your applications in Azure Active Directory B2C.

Register the app (java-spring-webapp-auth-b2c)

To register the app, use the following steps:

  1. Navigate to the Azure portal and select Azure AD B2C.

  2. Select App Registrations on the navigation pane, then select New registration.

  3. In the Register an application page that appears, enter the following application registration information:

    • In the Name section, enter a meaningful application name for display to users of the app - for example, java-spring-webapp-auth-b2c.
    • Under Supported account types, select Accounts in any identity provider or organizational directory (for authenticating users with user flows).
    • In the Redirect URI (optional) section, select Web in the combo-box and enter the following redirect URI: http://localhost:8080/login/oauth2/code/.

  4. Select Register to create the application.

  5. On the app's registration page, find and copy the Application (client) ID value to use later. You use this value in your app's configuration file or files.

  6. Select Save to save your changes.

  7. On the app's registration page, select the Certificates & secrets pane on the navigation pane to open the page to generate secrets and upload certificates.

  8. In the Client secrets section, select New client secret.

  9. Type a description - for example, app secret.

  10. Select one of the available durations as per your security concerns - for example, In 2 years.

  11. Select Add. The generated value is displayed.

  12. Copy and save the generated value for use in later steps. You need this value for your code's configuration files. This value isn't displayed again, and you can't retrieve it by any other means. So, be sure to save it from the Azure portal before you navigate to any other screen or pane.

Configure the app (java-spring-webapp-auth-b2c) to use your app registration

Use the following steps to configure the app:

Note

In the following steps, ClientID is the same as Application ID or AppId.

  1. Open the project in your IDE.

  2. Open the src/main/resources/application.yml file.

  3. Find the client-id property and replace the existing value with the application ID or clientId of the java-spring-webapp-auth-b2c application from the Azure portal.

  4. Find the client-secret property and replace the existing value with the value you saved during the creation of the java-spring-webapp-auth-b2c application from the Azure portal.

  5. Find the base-uri property and replace the two instances of the value fabrikamb2c with the name of the Azure AD B2C tenant in which you created the java-spring-webapp-auth-b2c application in the Azure portal.

  6. Find the sign-up-or-sign-in property and replace it with the name of the sign-up/sign-in user-flow policy you created in the Azure AD B2C tenant in which you created the java-spring-webapp-auth-b2c application in the Azure portal.

  7. Find the profile-edit property and replace it with the name of the password reset user-flow policy you created in the Azure AD B2C tenant in which you created the java-spring-webapp-auth-b2c application in the Azure portal.

  8. Find the password-reset property and replace it with the name of the edit profile user-flow policy you created in the Azure AD B2C tenant in which you created the java-spring-webapp-auth-b2c application in the Azure portal.

  9. Open the src/main/resources/templates/navbar.html file.

  10. Find the references to the b2c_1_susi and b2c_1_edit_profile flows and replace them with your sign-up-sign-in and profile-edit user-flows.

Run the sample

The following sections show you how to deploy the sample to Azure Spring Apps.

Prerequisites

Prepare the Spring project

Use the following steps to prepare the project:

  1. Use the following Maven command to build the project:

    mvn clean package

  2. Run the sample project locally by using the following command:

    mvn spring-boot:run

Configure the Maven plugin

Run the following command in the root of the project to configure the app using the Maven plugin for Azure Spring Apps:

mvn com.microsoft.azure:azure-spring-apps-maven-plugin:1.19.0:config

The following list describes the command interactions:

  • OAuth2 login: You need to authorize the sign-in to Azure based on the OAuth2 protocol.
  • Select subscription: Select the subscription list number where you want to create your Azure Spring Apps instance, which defaults to the first subscription in the list. If you want to use the default number, press Enter.
  • Input the Azure Spring Apps name: Enter the name for the spring apps instance you want to create. If you want to use the default name, press Enter.
  • Input the resource group name: Enter the name for the resource group you want to create your spring apps instance in. If you want to use the default name, press Enter.
  • Skus: Select the SKU you want to use for your spring apps instance. If you want to use the default number, press Enter.
  • Input the app name (demo): Provide an app name. If you want to use the default project artifact ID, press Enter.
  • Runtimes: Select the runtime you want to use for your spring apps instance. In this case, you should use the default number, so press Enter.
  • Expose public access for this app (boot-for-azure): Press y.
  • Confirm to save all the above configurations: Press y. If you press n, the configuration isn't saved in the .pom file.

The following example shows the output of the deployment process:

Summary of properties:
Subscription id   : 12345678-1234-1234-1234-123456789101
Resource group name : rg-ms-identity-spring-boot-webapp
Azure Spring Apps name : cluster-ms-identity-spring-boot-webapp
Runtime Java version : Java 11
Region            : eastus
Sku               : Standard
App name          : ms-identity-spring-boot-webapp
Public access     : true
Instance count/max replicas : 1
CPU count         : 1
Memory size(GB)   : 2
Confirm to save all the above configurations (Y/n):
[INFO] Configurations are saved to: /home/user/ms-identity-java-spring-tutorial/1-Authentication/sign-in/pom.    xml
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  01:57 min
[INFO] Finished at: 2024-02-14T13:50:44Z
[INFO] ------------------------------------------------------------------------

After you've confirmed your choices, the plugin adds the required plugin element and settings to your project's pom.xml file to configure your app to run in Azure Spring Apps.

The relevant portion of the pom.xml file should look similar to the following example:

<plugin>
    <groupId>com.microsoft.azure</groupId>
    <artifactId>azure-spring-apps-maven-plugin</artifactId>
    <version>1.19.0</version>
    <configuration>
        <subscriptionId>12345678-1234-1234-1234-123456789101</subscriptionId>
        <resourceGroup>rg-ms-identity-spring-boot-webapp</resourceGroup>
        <clusterName>cluster-ms-identity-spring-boot-webapp</clusterName>
        <region>eastus</region>
        <sku>Standard</sku>
        <appName>ms-identity-spring-boot-webapp</appName>
        <isPublic>true</isPublic>
        <deployment>
            <cpu>1</cpu>
            <memoryInGB>2</memoryInGB>
            <instanceCount>1</instanceCount>
            <runtimeVersion>Java 11</runtimeVersion>
            <resources>
                <resource>
                    <directory>${project.basedir}/target</directory>
                    <includes>
                        <include>*.jar</include>
                    </includes>
                </resource>
            </resources>
        </deployment>
    </configuration>
</plugin>

You can modify the configurations for Azure Spring Apps directly in your pom.xml file. Some common configurations are listed in the following table:

Property Required Description
subscriptionId false The subscription ID.
resourceGroup true The Azure resource group for your Azure Spring Apps instance.
clusterName true The Azure Spring Apps cluster name. In case you're using a subscription and resource group that already have an Azure Spring Apps instance deployed, you can also use this existing cluster to deploy to.
appName true The name of your app in Azure Spring Apps.
region false The region in which to host your Azure Spring Apps instance. The default value is eastus. For valid regions, see Supported Regions.
sku false The pricing tier for your Azure Spring Apps instance. The default value is Basic, which is suited only for development and test environments.
runtime false The runtime environment configuration. For more information, see Configuration Details.
deployment false The deployment configuration. For more information, see Configuration Details.

For the complete list of configurations, see the plugin reference documentation. All the Azure Maven plugins share a common set of configurations. For these configurations, see Common Configurations. For configurations specific to Azure Spring Apps, see Azure Spring Apps: Configuration Details.

Be sure to save aside the clusterName and appName values for later use.

Prepare the app for deployment

When you deploy your application to Azure Spring Apps, your redirect URL changes to the redirect URL of your deployed app instance in Azure Spring Apps. Use the following steps to change these settings in your application.yml file:

  1. Navigate to your app's src\main\resources\application.yml file and change the value of post-logout-redirect-uri to your deployed app's domain name, as shown in the following example. For example, if you chose cluster-ms-identity-spring-boot-webapp for your Azure Spring Apps instance in the previous step and ms-identity-spring-boot-webapp for your app name, you must now use https://cluster-ms-identity-spring-boot-webapp-ms-identity-spring-boot-webapp.azuremicroservices.io for the post-logout-redirect-uri value.

    post-logout-redirect-uri: https://<cluster-name>-<app-name>.azuremicroservices.io

  2. After saving this file, use the following command to rebuild your app:

    mvn clean package

Important

The application.yml file of the application currently holds the value of your client secret in the client-secret parameter. It isn't good practice to keep this value in this file. You might also be taking a risk if you commit it to a Git repository.

As an extra security step, you can store this value in Azure Key Vault and load the secret from Key Vault to make it available in your application.

Update your Microsoft Entra ID app registration

Because the redirect URI changes to your deployed app on Azure Spring Apps, you also need to change the redirect URI in your Microsoft Entra ID app registration. Use the following steps to make this change:

  1. Navigate to the Microsoft identity platform for developers App registrations page.

  2. Use the search box to search for your app registration - for example, java-servlet-webapp-authentication.

  3. Open your app registration by selecting its name.

  4. Select Authentication from the menu.

  5. In the Web - Redirect URIs section, select Add URI.

  6. Fill out the URI of your app, appending /login/oauth2/code/ - for example, https://<cluster-name>-<app-name>.azuremicroservices.io/login/oauth2/code/.

  7. Select Save.

Deploy the app

Use the following command to deploy the app:

mvn azure-spring-apps:deploy

The following list describes the command interaction:

  • OAuth2 login: You need to authorize the sign-in to Azure based on the OAuth2 protocol.

After the command is executed, you can see from the following log messages that the deployment was successful:

[INFO] Deployment(default) is successfully created
[INFO] Starting Spring App after deploying artifacts...
[INFO] Deployment Status: Running
[INFO]   InstanceName:demo-default-x-xxxxxxxxxx-xxxxx  Status:Running Reason:null       DiscoverStatus:UNREGISTERED
[INFO]   InstanceName:demo-default-x-xxxxxxxxx-xxxxx  Status:Terminating Reason:null       DiscoverStatus:UNREGISTERED
[INFO] Getting public url of app(demo)...
[INFO] Application url: https://<your-Azure-Spring-Apps-instance-name>-demo.azuremicroservices.io

Validate the app

After the deployment finishes, access the application with the output application URL. Use the following steps to check the app's logs to investigate any deployment issue:

  1. Access the output application URL from the Outputs page of the Deployment section.

  2. From the navigation pane of the Azure Spring Apps instance Overview page, select Logs to check the app's logs.

Explore the sample

Use the following steps to explore the sample:

  1. Notice the signed-in or signed-out status displayed at the center of the screen.
  2. Select the context-sensitive button in the corner. This button reads Sign In when you first run the app. Alternatively, select the link to token details. Because this page is protected and requires authentication, you're automatically redirected to the sign-in page.
  3. On the next page, follow the instructions and sign in with an account of your chosen identity provider. You can also choose to sign up or sign in to a local account on the B2C tenant using an email address.
  4. Upon successful completion of the sign-in flow, you should be redirected to the home page - which shows the sign in status - or the token details page, depending on which button triggered your sign-in flow.
  5. Notice that the context-sensitive button now says Sign out and displays your username.
  6. If you're on the home page, select ID Token Details to see some of the ID token's decoded claims.
  7. Edit your profile. Select edit profile to change details like your display name, place of residence, and profession.
  8. Use the button in the corner to sign out. The status page reflects the new state.

About the code

This sample demonstrates how to use Azure AD B2C Spring Boot Starter client library for Java to sign in users into your Azure AD B2C tenant. The sample also makes use of the Spring Oauth2 Client and Spring Web boot starters. The sample uses claims from the ID token obtained from Azure AD B2C to display the details of the signed-in user.

Contents

The following table shows the contents of the sample project folder:

File/folder Description
pom.xml Application dependencies.
src/main/resources/templates/ Thymeleaf Templates for UI.
src/main/resources/application.yml Application and Microsoft Entra Boot Starter library configuration.
src/main/java/com/microsoft/azuresamples/msal4j/msidentityspringbootwebapp/ This directory contains the main application entry point, controller, and config classes.
.../MsIdentitySpringBootWebappApplication.java Main class.
.../SampleController.java Controller with endpoint mappings.
.../SecurityConfig.java Security configuration - for example, which routes require authentication.
.../Utilities.java Utility class - for example, filter ID token claims.
CHANGELOG.md List of changes to the sample.
CONTRIBUTING.md Guidelines for contributing to the sample.
LICENSE The license for the sample.

ID token claims

To extract token details, the app makes use of Spring Security's AuthenticationPrincipal and OidcUser object in a request mapping, as shown in the following example, as shown in the following example. See the Sample Controller for the full details of how this app makes use of ID token claims.

import org.springframework.security.oauth2.core.oidc.user.OidcUser;
import org.springframework.security.core.annotation.AuthenticationPrincipal;
//...
@GetMapping(path = "/some_path")
public String tokenDetails(@AuthenticationPrincipal OidcUser principal) {
    Map<String, Object> claims = principal.getIdToken().getClaims();
}

For sign-in, the app makes a request to the Azure AD B2C sign-in endpoint automatically configured by Azure AD B2C Spring Boot Starter client library for Java, as shown in the following example:

<a class="btn btn-success" href="/oauth2/authorization/{your-sign-up-sign-in-user-flow}">Sign In</a>

For sign-out, the app makes a POST request to the logout endpoint, as shown in the following example:

<form action="#" th:action="@{/logout}" method="post">
  <input class="btn btn-warning" type="submit" value="Sign Out" />
</form>

Authentication-dependent UI elements

The app has some simple logic in the UI template pages for determining content to display based on whether the user is authenticated, as shown in the following example using Spring Security Thymeleaf tags:

<div sec:authorize="isAuthenticated()">
  this content only shows to authenticated users
</div>
<div sec:authorize="isAnonymous()">
  this content only shows to not-authenticated users
</div>

Protect routes with WebSecurityConfigurerAdapter

By default, the app protects the ID Token Details page so that only signed-in users can access it. The app configures these routes from the app.protect.authenticated property from the application.yml file. To configure your app's specific requirements, you can extend WebSecurityConfigurerAdapter in one of your classes. For an example, see this app's SecurityConfig class, shown in the following code:

@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Value("${app.protect.authenticated}")
    private String[] protectedRoutes;

    private final AADB2COidcLoginConfigurer configurer;

    public SecurityConfig(AADB2COidcLoginConfigurer configurer) {
        this.configurer = configurer;
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        // @formatter:off
        http.authorizeRequests()
            .antMatchers(protectedRoutes).authenticated()     // limit these pages to authenticated users (default: /token_details)
            .antMatchers("/**").permitAll()                  // allow all other routes.
            .and()
            .apply(configurer)
            ;
        // @formatter:off
    }
}

More information

For more information about how OAuth 2.0 protocols work in this scenario and other scenarios, see Authentication Scenarios for Microsoft Entra ID.