Enable Tomcat app sign-in and access to Microsoft Graph - Azure

Article
03/19/2024

This article demonstrates a Java Tomcat app that signs in users and obtains an access token for calling Microsoft Graph. It uses the Microsoft Authentication Library (MSAL) for Java.

The following diagram shows the topology of the app:

Diagram that shows the topology of the app.

The client app uses MSAL for Java (MSAL4J) to sign in a user and obtain an access token for Microsoft Graph from Microsoft Entra ID. The access token proves that the user is authorized to access the Microsoft Graph API endpoint as defined in the scope.

Prerequisites

Java 8 or higher
Maven 3
A Microsoft Entra ID tenant. For more information, see How to get a Microsoft Entra ID tenant.
A user account in your own Microsoft Entra ID tenant if you want to work with accounts in your organizational directory only - that is, in single-tenant mode. If you haven't created a user account in your tenant yet, you should do so before proceeding. For more information, see How to create, invite, and delete users.
A user account in any organization's Microsoft Entra ID tenant if you want to work with accounts in any organizational directory - that is, in multitenant mode. This sample must be modified to work with a personal Microsoft account. If you haven't created a user account in your tenant yet, you should do so before proceeding. For more information, see How to create, invite, and delete users.
A personal Microsoft account - for example, Xbox, Hotmail, Live, and so on - if you want to work with personal Microsoft accounts.

Recommendations

Some familiarity with the Java / Jakarta Servlets.
Some familiarity with Linux/OSX terminal.
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-msal-java-samples.git
cd 3-java-servlet-web-app/2-Authorization-I/call-graph

Alternatively, navigate to the ms-identity-msal-java-samples 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.

Register the sample application with your Microsoft Entra ID tenant

There's one project in this sample. The following sections show you how to register the app using the Azure portal.

Choose the Microsoft Entra ID tenant where you want to create your applications

To choose your tenant, use the following steps:

Sign in to the Azure portal.
If your account is present in more than one Microsoft Entra ID tenant, select your profile in the corner of the Azure portal, and then select Switch directory to change your session to the desired Microsoft Entra ID tenant.

Register the app (java-servlet-webapp-call-graph)

First, register a new app in the Azure portal by following the instructions in Quickstart: Register an application with the Microsoft identity platform.

Then, use the following steps to complete the registration:

Navigate to the Microsoft identity platform for developers App registrations page.
Select New registration.
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-servlet-webapp-call-graph.
- Under Supported account types, select one of the following options:
  - Select Accounts in this organizational directory only if you're building an application for use only by users in your tenant - that is, a single-tenant application.
  - Select Accounts in any organizational directory if you'd like users in any Microsoft Entra ID tenant to be able to use your application - that is, a multitenant application.
  - Select Accounts in any organizational directory and personal Microsoft accounts for the widest set of customers - that is, a multitenant application that also supports Microsoft personal accounts.
- Select Personal Microsoft accounts for use only by users of personal Microsoft accounts - for example, Hotmail, Live, Skype, and Xbox accounts.
- In the Redirect URI section, select Web in the combo-box and enter the following redirect URI: http://localhost:8080/msal4j-servlet-graph/auth/redirect.
Select Register to create the application.
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.
Select Save to save your changes.
On the app's registration page, select Certificates & secrets on the navigation pane to open the page where you can generate secrets and upload certificates.
In the Client secrets section, select New client secret.
Type a description - for example, app secret.
Select one of the available durations: In 1 year, In 2 years, or Never Expires.
Select Add. The generated value is displayed.
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.
On the app's registration page, select API permissions from the navigation pane to open the page to add access to the APIs that your application needs.
Select Add permissions.
Ensure that the Microsoft APIs tab is selected.
In the Commonly used Microsoft APIs section, select Microsoft Graph.
In the Delegated permissions section, select User.Read from the list. Use the search box if necessary.
Select Add permissions.

Configure the app (java-servlet-webapp-call-graph) 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.

Open the project in your IDE.
Open the ./src/main/resources/authentication.properties file.
Find the string {enter-your-tenant-id-here}. Replace the existing value with one of the following values:
- Your Microsoft Entra ID tenant ID if you registered your app with the Accounts in this organizational directory only option.
- The word organizations if you registered your app with the Accounts in any organizational directory option.
- The word common if you registered your app with the Accounts in any organizational directory and personal Microsoft accounts option.
- The word consumers if you registered your app with the Personal Microsoft accounts option.
Find the string {enter-your-client-id-here} and replace the existing value with the application ID or clientId of the java-servlet-webapp-call-graph application copied from the Azure portal.
Find the string {enter-your-client-secret-here} and replace the existing value with the value you saved during the creation of the java-servlet-webapp-call-graph app, in the Azure portal.

Build the sample

To build the sample using Maven, navigate to the directory containing the pom.xml file for the sample, and then run the following command:

mvn clean package

This command generates a .war file that you can run on various application servers.

The following sections show you how to deploy the sample to Azure App Service.

Prerequisites

Maven Plugin for Azure App Service apps

If Maven isn't your preferred development tool, see the following similar tutorials that use other tools:

Configure the Maven plugin

When you deploy to Azure App Service, the deployment automatically uses your Azure credentials from the Azure CLI. If the Azure CLI isn't installed locally, then the Maven plugin authenticates with OAuth or device sign-in. For more information, see authentication with Maven plugins.

Use the following steps to configure the plugin:

Run the following command to configure the deployment. This command helps you to set up the Azure App Service operating system, Java version, and Tomcat version.
```
mvn com.microsoft.azure:azure-webapp-maven-plugin:2.13.0:config
```
For Create new run configuration, press Y, then press Enter.
For Define value for OS, press 1 for Windows, or 2 for Linux, then press Enter.
For Define value for javaVersion, press 2 for Java 11, then press Enter.
For Define value for webContainer, press 4 for Tomcat 9.0, then press Enter.
For Define value for pricingTier, press Enter to select the default P1v2 tier.
For Confirm, press Y, then press Enter.

The following example shows the output of the deployment process:

Please confirm webapp properties
AppName : msal4j-servlet-auth-1707209552268
ResourceGroup : msal4j-servlet-auth-1707209552268-rg
Region : centralus
PricingTier : P1v2
OS : Linux
Java Version: Java 11
Web server stack: Tomcat 9.0
Deploy to slot : false
Confirm (Y/N) [Y]: [INFO] Saving configuration to pom.
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  37.112 s
[INFO] Finished at: 2024-02-06T08:53:02Z
[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 App Service.

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

<build>
    <plugins>
        <plugin>
            <groupId>com.microsoft.azure</groupId>
            <artifactId>>azure-webapp-maven-plugin</artifactId>
            <version>x.xx.x</version>
            <configuration>
                <schemaVersion>v2</schemaVersion>
                <resourceGroup>your-resourcegroup-name</resourceGroup>
                <appName>your-app-name</appName>
            ...
            </configuration>
        </plugin>
    </plugins>
</build>

You can modify the configurations for App Service directly in your pom.xml. 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 app.
`appName`	true	The name of your app.
`region`	false	The region in which to host your app. The default value is `centralus`. For valid regions, see Supported Regions.
`pricingTier`	false	The pricing tier for your app. The default value is `P1v2` for a production workload. The recommended minimum value for Java development and testing is `B2`. For more information, see App Service Pricing.
`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 App Service, see Azure app: Configuration Details.

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

Prepare the app for deployment

When you deploy your application to App Service, your redirect URL changes to the redirect URL of your deployed app instance. Use the following steps to change these settings in your properties file:

Navigate to your app's authentication.properties file and change the value of app.homePage to your deployed app's domain name, as shown in the following example. For example, if you chose example-domain for your app name in the previous step, you must now use https://example-domain.azurewebsites.net for the app.homePage value. Be sure that you've also changed the protocol from http to https.
```
# app.homePage is by default set to dev server address and app context path on the server
# for apps deployed to azure, use https://your-sub-domain.azurewebsites.net
app.homePage=https://<your-app-name>.azurewebsites.net
```
After saving this file, use the following command to rebuild your app:
```
mvn clean package
```

Important

In this same authentication.properties file, you have a setting for your aad.secret. It isn't a good practice to deploy this value to App Service. Neither is it a good practice to leave this value in your code and potentially push it up to your git repository. For removing this secret value from your code, you can find more detailed guidance in the Deploy to App Service - Remove secret section. This guidance adds extra steps for pushing the secret value to Key Vault and to use Key Vault References.

Update your Microsoft Entra ID app registration

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

Navigate to the Microsoft identity platform for developers App registrations page.
Use the search box to search for your app registration - for example, java-servlet-webapp-authentication.
Open your app registration by selecting its name.
Select Authentication from the menu.
In the Web - Redirect URIs section, select Add URI.
Fill out the URI of your app, appending /auth/redirect - for example, https://<your-app-name>.azurewebsites.net/auth/redirect.
Select Save.

Deploy the app

You're now ready to deploy your app to Azure App Service. Use the following command to make sure you're signed in to your Azure environment to execute the deployment:

az login

With all the configuration ready in your pom.xml file, you can now use the following command to deploy your Java app to Azure:

mvn package azure-webapp:deploy

After deployment is completed, your application is ready at http://<your-app-name>.azurewebsites.net/. Open the URL with your local web browser, where you should see the start page of the msal4j-servlet-auth application.

To run the sample on Tomcat, use the following steps:

In your Tomcat installation, ensure that there's an entry in tomcat/conf/server.xml for the address you want to host your application on.

By default, the samples just expect to connect to http://localhost:8080 or https://localhost:8443, as defined in the app.homePage value in the authentication.properties file.
Copy the .war file you generated with Maven to the /webapps/ directory in your Tomcat installation, and start the Tomcat server.
After Tomcat starts, open your browser and navigate to whatever URL you defined in step 1 and you should be able to access the application.

Explore the sample

Use the following steps to explore the sample:

Notice the signed-in or signed-out status displayed at the center of the screen.
Select the context-sensitive button in the corner. This button reads Sign In when you first run the app.
On the next page, follow the instructions and sign in with an account in the Microsoft Entra ID tenant.
On the consent screen, notice the scopes that are being requested.
Notice that the context-sensitive button now says Sign out and displays your username.
Select ID Token Details to see some of the ID token's decoded claims.
Select Call Graph to make a call to Microsoft Graph's /me endpoint and see a selection of the user details obtained.
Use the button in the corner to sign out.

About the code

This sample uses MSAL for Java (MSAL4J) to sign a user in and obtain a token for Microsoft Graph API. It uses Microsoft Graph SDK for Java to obtain data from Graph. You must add these libraries to your projects using Maven.

If you want to replicate this sample's behavior, you can copy the pom.xml file and the contents of the helpers and authservlets folders in the src/main/java/com/microsoft/azuresamples/msal4j folder. You also need the authentication.properties file. These classes and files contain generic code that you can use in a wide array of applications. You can copy the rest of the sample as well, but the other classes and files are built specifically to address this sample's objective.

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

File/folder	Description
src/main/java/com/microsoft/azuresamples/msal4j/callgraphwebapp/	This directory contains the classes that define the app's backend business logic.
src/main/java/com/microsoft/azuresamples/msal4j/authservlets/	This directory contains the classes that are used for sign in and sign out endpoints.
____Servlet.java	All of the endpoints available are defined in .java classes ending in ____Servlet.java.
src/main/java/com/microsoft/azuresamples/msal4j/helpers/	Helper classes for authentication.
AuthenticationFilter.java	Redirects unauthenticated requests to protected endpoints to a 401 page.
src/main/resources/authentication.properties	Microsoft Entra ID and program configuration.
src/main/webapp/	This directory contains the UI - JSP templates
CHANGELOG.md	List of changes to the sample.
CONTRIBUTING.md	Guidelines for contributing to the sample.
LICENSE	The license for the sample.

ConfidentialClientApplication

A ConfidentialClientApplication instance is created in the AuthHelper.java file, as shown in the following example. This object helps craft the Microsoft Entra ID authorization URL and also helps exchange the authentication token for an access token.

// getConfidentialClientInstance method
IClientSecret secret = ClientCredentialFactory.createFromSecret(SECRET);
confClientInstance = ConfidentialClientApplication
                     .builder(CLIENT_ID, secret)
                     .authority(AUTHORITY)
                     .build();

The following parameters are used for instantiation:

The client ID of the app.
The client secret, which is a requirement for Confidential Client Applications.
The Microsoft Entra ID Authority, which includes your Microsoft Entra tenant ID.

In this sample, these values are read from the authentication.properties file using a properties reader in the Config.java file.

Step-by-step walkthrough

The following steps provide a walkthrough of the app's functionality:

The first step of the sign-in process is to send a request to the /authorize endpoint on for your Microsoft Entra ID tenant. The MSAL4J ConfidentialClientApplication instance is used to construct an authorization request URL. The app redirects the browser to this URL, which is where the user signs in.
```
final ConfidentialClientApplication client = getConfidentialClientInstance();
AuthorizationRequestUrlParameters parameters = AuthorizationRequestUrlParameters.builder(Config.REDIRECT_URI, Collections.singleton(Config.SCOPES))
        .responseMode(ResponseMode.QUERY).prompt(Prompt.SELECT_ACCOUNT).state(state).nonce(nonce).build();

final String authorizeUrl = client.getAuthorizationRequestUrl(parameters).toString();
contextAdapter.redirectUser(authorizeUrl);
```
The following list describes the features of this code:
- AuthorizationRequestUrlParameters: Parameters that must be set in order to build an AuthorizationRequestUrl.
- REDIRECT_URI: Where Microsoft Entra ID redirects the browser - along with the auth code - after collecting user credentials. It must match the redirect URI in the Microsoft Entra ID app registration in the Azure portal
- SCOPES: Scopes are permissions requested by the application.
  - Normally, the three scopes openid profile offline_access suffice for receiving an ID token response.
  - Full list of scopes requested by the app can be found in the authentication.properties file. You can add more scopes such as User.Read.
The user is presented with a sign-in prompt by Microsoft Entra ID. If the sign-in attempt is successful, the user's browser is redirected to the app's redirect endpoint. A valid request to this endpoint contains an authorization code.

The ConfidentialClientApplication instance then exchanges this authorization code for an ID token and access token from Microsoft Entra ID.

// First, validate the state, then parse any error codes in response, then extract the authCode. Then:
// build the auth code params:
final AuthorizationCodeParameters authParams = AuthorizationCodeParameters
        .builder(authCode, new URI(Config.REDIRECT_URI)).scopes(Collections.singleton(Config.SCOPES)).build();

// Get a client instance and leverage it to acquire the token:
final ConfidentialClientApplication client = AuthHelper.getConfidentialClientInstance();
final IAuthenticationResult result = client.acquireToken(authParams).get();

The following list describes the features of this code:

AuthorizationCodeParameters: Parameters that must be set in order to exchange the Authorization Code for an ID and/or access token.
authCode: The authorization code that was received at the redirect endpoint.
REDIRECT_URI: The redirect URI used in the previous step must be passed again.
SCOPES: The scopes used in the previous step must be passed again.

If acquireToken is successful, the token claims are extracted. If the nonce check passes, the results are placed in context - an instance of IdentityContextData - and saved to the session. The application can then instantiate the IdentityContextData from the session by way of an instance of IdentityContextAdapterServlet whenever it needs access to it, as shown in the following code:

// parse IdToken claims from the IAuthenticationResult:
// (the next step - validateNonce - requires parsed claims)
context.setIdTokenClaims(result.idToken());

// if nonce is invalid, stop immediately! this could be a token replay!
// if validation fails, throws exception and cancels auth:
validateNonce(context);

// set user to authenticated:
context.setAuthResult(result, client.tokenCache().serialize());

Protect the routes

For information about how the sample app filters access to routes, see AuthenticationFilter.java. In the authentication.properties file, the app.protect.authenticated property contains the comma-separated routes that only authenticated users can access, as shown in the following example:

# for example, /token_details requires any user to be signed in and does not require special roles or groups claim(s)
app.protect.authenticated=/token_details, /call_graph

Call graph

When the user navigates to /call_graph, the application creates an instance of the IGraphServiceClient - from the Java Graph SDK - passing along the signed-in user's access token. The Graph client places the access token in the Authorization headers of its requests. The app then asks the Graph client to call the /me endpoint to yield details for the currently signed-in user.

If you already have a valid access token for Graph Service with the User.Read scope, you only need the following code to get access to the /me endpoint:

//CallGraphServlet.java
User user = GraphHelper.getGraphClient(contextAdapter).me().buildRequest().get();

Scopes

Scopes tell Microsoft Entra ID the level of access that the application is requesting.

Based on the requested scopes, Microsoft Entra ID presents a consent dialogue to the user upon sign-in. If the user consents to one or more scopes and obtains a token, the scopes-consented-to are encoded into the resulting access_token.

For the scopes requested by the application, see authentication.properties. By default, the application sets the scopes value to User.Read. This particular Microsoft Graph API scope is for accessing the information of the current signed-in user. The graph endpoint for accessing this info is https://graph.microsoft.com/v1.0/me. Any valid requests made to this endpoint must bear an access_token that contains the scope User.Read in the Authorization header.

Share via

Prerequisites

Recommendations

Set up the sample

Clone or download the sample repository

Register the sample application with your Microsoft Entra ID tenant

Choose the Microsoft Entra ID tenant where you want to create your applications

Register the app (java-servlet-webapp-call-graph)

Configure the app (java-servlet-webapp-call-graph) to use your app registration

Build the sample

Run the sample

Prerequisites

Configure the Maven plugin

Prepare the app for deployment

Update your Microsoft Entra ID app registration

Deploy the app

Explore the sample

About the code

Contents

ConfidentialClientApplication

Step-by-step walkthrough

Protect the routes

Call graph

Scopes

More information

Feedback

Additional resources

Share via

Enable Java Tomcat apps to sign in users and access Microsoft Graph

Prerequisites

Recommendations

Set up the sample

Clone or download the sample repository

Register the sample application with your Microsoft Entra ID tenant

Choose the Microsoft Entra ID tenant where you want to create your applications

Register the app (java-servlet-webapp-call-graph)

Configure the app (java-servlet-webapp-call-graph) to use your app registration

Build the sample

Run the sample

Prerequisites

Configure the Maven plugin

Prepare the app for deployment

Update your Microsoft Entra ID app registration

Deploy the app

Explore the sample

About the code

Contents

ConfidentialClientApplication

Step-by-step walkthrough

Protect the routes

Call graph

Scopes

More information

Feedback

Additional resources