Tutorial: Access Microsoft Graph from a secured app as the app

Learn how to access Microsoft Graph from a web app running on Azure App Service.

You want to call Microsoft Graph for the web app. A safe way to give your web app access to data is to use a system-assigned managed identity. A managed identity from Azure Active Directory allows App Service to access resources through role-based access control (RBAC), without requiring app credentials. After assigning a managed identity to your web app, Azure takes care of the creation and distribution of a certificate. You don't have to worry about managing secrets or app credentials.

In this tutorial, you learn how to:

• Create a system-assigned managed identity on a web app.
• Add Microsoft Graph API permissions to a managed identity.
• Call Microsoft Graph from a web app by using managed identities.

If you don't have an Azure subscription, create an Azure free account before you begin.

Prerequisites

• A web application running on Azure App Service that has the App Service authentication/authorization module enabled.

Enable managed identity on app

If you create and publish your web app through Visual Studio, the managed identity was enabled on your app for you. In your app service, select Identity in the left pane and then select System assigned. Verify that Status is set to On. If not, select Save and then select Yes to enable the system-assigned managed identity. When the managed identity is enabled, the status is set to On and the object ID is available.

Take note of the Object ID value, which you'll need in the next step.

Grant access to Microsoft Graph

When accessing the Microsoft Graph, the managed identity needs to have proper permissions for the operation it wants to perform. Currently, there's no option to assign such permissions through the Azure portal. The following script will add the requested Microsoft Graph API permissions to the managed identity service principal object.

PowerShell

# Install the module. (You need admin on the machine.)
# Install-Module AzureAD.

# Your tenant ID (in the Azure portal, under Azure Active Directory > Overview).
$TenantID="<tenant-id>"
$resourceGroup = "securewebappresourcegroup"
$webAppName="SecureWebApp-20201102125811"

# Get the ID of the managed identity for the web app.
$spID = (Get-AzWebApp -ResourceGroupName $resourceGroup -Name $webAppName).identity.principalid

# Check the Microsoft Graph documentation for the permission you need for the operation.
$PermissionName = "User.Read.All"

Connect-AzureAD -TenantId $TenantID

# Get the service principal for Microsoft Graph.
# First result should be AppId 00000003-0000-0000-c000-000000000000
$GraphServicePrincipal = Get-AzureADServicePrincipal -SearchString "Microsoft Graph" | Select-Object -first 1

# Assign permissions to the managed identity service principal.
$AppRole = $GraphServicePrincipal.AppRoles | `
Where-Object {$_.Value -eq $PermissionName -and $_.AllowedMemberTypes -contains "Application"}

New-AzureAdServiceAppRoleAssignment -ObjectId $spID -PrincipalId $spID `
-ResourceId $GraphServicePrincipal.ObjectId -Id $AppRole.Id

Azure CLI

az login

webAppName="SecureWebApp-20201106120003"

spId=$(az resource list -n $webAppName --query [*].identity.principalId --out tsv)

graphResourceId=$(az ad sp list --display-name "Microsoft Graph" --query [0].id --out tsv)

appRoleId=$(az ad sp list --display-name "Microsoft Graph" --query "[0].appRoles[?value=='User.Read.All' && contains(allowedMemberTypes, 'Application')].id" --output tsv)

uri=https://graph.microsoft.com/v1.0/servicePrincipals/$spId/appRoleAssignments

body="{'principalId':'$spId','resourceId':'$graphResourceId','appRoleId':'$appRoleId'}"

az rest --method post --uri $uri --body $body --headers "Content-Type=application/json"

After executing the script, you can verify in the Azure portal that the requested API permissions are assigned to the managed identity.

Go to Azure Active Directory, and then select Enterprise applications. This pane displays all the service principals in your tenant. In Managed Identities, select the service principal for the managed identity.

If you're following this tutorial, there are two service principals with the same display name (SecureWebApp2020094113531, for example). The service principal that has a Homepage URL represents the web app in your tenant. The service principal that appears in Managed Identities should not have a Homepage URL listed and the Object ID should match the object ID value of the managed identity in the previous step.

Select the service principal for the managed identity.

In Overview, select Permissions, and you'll see the added permissions for Microsoft Graph.

Call Microsoft Graph

C#

The ChainedTokenCredential, ManagedIdentityCredential, and EnvironmentCredential classes are used to get a token credential for your code to authorize requests to Microsoft Graph. Create an instance of the ChainedTokenCredential class, which uses the managed identity in the App Service environment or the development environment variables to fetch tokens and attach them to the service client. The following code example gets the authenticated token credential and uses it to create a service client object, which gets the users in the group.

To see this code as part of a sample application, see the sample on GitHub.

Install the Microsoft.Identity.Web.MicrosoftGraph client library package

Install the Microsoft.Identity.Web.MicrosoftGraph NuGet package in your project by using the .NET Core command-line interface or the Package Manager Console in Visual Studio.

.NET Core command-line

Open a command line, and switch to the directory that contains your project file.

Run the install commands.

dotnet add package Microsoft.Identity.Web.MicrosoftGraph

Package Manager Console

Open the project/solution in Visual Studio, and open the console by using the Tools > NuGet Package Manager > Package Manager Console command.

Run the install commands.

Install-Package Microsoft.Identity.Web.MicrosoftGraph

Example

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Azure.Identity;​
using Microsoft.Graph.Core;​​
using System.Net.Http.Headers;

...

public IList<MSGraphUser> Users { get; set; }

public async Task OnGetAsync()
{
    // Create the Graph service client with a ChainedTokenCredential which gets an access
    // token using the available Managed Identity or environment variables if running
    // in development.
    var credential = new ChainedTokenCredential(
        new ManagedIdentityCredential(),
        new EnvironmentCredential());
    var token = credential.GetToken(
        new Azure.Core.TokenRequestContext(
            new[] { "https://graph.microsoft.com/.default" }));

    var accessToken = token.Token;
    var graphServiceClient = new GraphServiceClient(
        new DelegateAuthenticationProvider((requestMessage) =>
        {
            requestMessage
            .Headers
            .Authorization = new AuthenticationHeaderValue("bearer", accessToken);

            return Task.CompletedTask;
        }));

    // MSGraphUser is a DTO class being used to hold User information from the graph service client call
    List<MSGraphUser> msGraphUsers = new List<MSGraphUser>();
    try
    {
        var users =await graphServiceClient.Users.Request().GetAsync();
        foreach(var u in users)
        {
            MSGraphUser user = new MSGraphUser();
            user.userPrincipalName = u.UserPrincipalName;
            user.displayName = u.DisplayName;
            user.mail = u.Mail;
            user.jobTitle = u.JobTitle;

            msGraphUsers.Add(user);
        }
    }
    catch(Exception ex)
    {
        string msg = ex.Message;
    }

    Users = msGraphUsers;
}

Node.js

The DefaultAzureCredential class from @azure/identity package is used to get a token credential for your code to authorize requests to Azure Storage. Create an instance of the DefaultAzureCredential class, which uses the managed identity to fetch tokens and attach them to the service client. The following code example gets the authenticated token credential and uses it to create a service client object, which gets the users in the group.

To see this code as part of a sample application, see the sample on GitHub.

Example

const graphHelper = require('../utils/graphHelper');
const { DefaultAzureCredential } = require("@azure/identity");

exports.getUsersPage = async(req, res, next) => {

    const defaultAzureCredential = new DefaultAzureCredential();
    
    try {
        const tokenResponse = await defaultAzureCredential.getToken("https://graph.microsoft.com/.default");

        const graphClient = graphHelper.getAuthenticatedClient(tokenResponse.token);

        const users = await graphClient
            .api('/users')
            .get();

        res.render('users', { user: req.session.user, users: users });   
    } catch (error) {
        next(error);
    }
}

To query Microsoft Graph, the sample uses the Microsoft Graph JavaScript SDK. The code for this is located in utils/graphHelper.js of the full sample:

getAuthenticatedClient = (accessToken) => {
    // Initialize Graph client
    const client = graph.Client.init({
        // Use the provided access token to authenticate requests
        authProvider: (done) => {
            done(null, accessToken);
        }
    });

    return client;
}

Clean up resources

If you're finished with this tutorial and no longer need the web app or associated resources, clean up the resources you created.

Next steps

Clean up resources)