Configure your App Service or Azure Functions app to use Microsoft Entra sign-in

Select another authentication provider to jump to it.

This article shows you how to configure authentication for Azure App Service or Azure Functions so that your app signs in users with the Microsoft identity platform (Microsoft Entra) as the authentication provider.

Choose a tenant for your application and its users

Before your application can sign in users, you first need to register it in a workforce or external tenant. If you're making your app available to employee or business guests, register your app in a workforce tenant. If your app is for consumers and business customers, register it in an external tenant.

1. Sign in to the Azure portal and navigate to your app.

2. On your app's left menu, select Authentication, and then select Add identity provider.

3. In the Add an identity provider page, select Microsoft as the Identity provider to sign in Microsoft and Microsoft Entra identities.

4. For Tenant type, select Workforce configuration (current tenant) for employees and business guests or select External configuration for consumers and business customers.

Choose the app registration

The App Service Authentication feature can automatically create an app registration for you or you can use a registration that you or a directory admin created separately.

Create a new app registration automatically, unless you need to create an app registration separately. You can customize the app registration in the Microsoft Entra admin center later if you want.

The following situations are the most common cases to use an existing app registration:

• Your account doesn't have permissions to create app registrations in your Microsoft Entra tenant.
• You want to use an app registration from a different Microsoft Entra tenant than the one your app is in.

Configure additional checks

Configure Additional checks, which determines which requests are allowed to access your application. You can customize this behavior now or adjust these settings later from the main Authentication screen by choosing Edit next to Authentication settings.

For Client application requirement, choose whether to:

• Allow requests only from this application itself
• Allow requests from specific client applications
• Allow requests from any application (Not recommended)

For Identity requirement, choose whether to:

• Allow requests from any identity
• Allow requests from specific identities

For Tenant requirement, choose whether to:

• Allow requests only from the issuer tenant
• Allow requests from specific tenants
• Use default restrictions based on issuer

Your app may still need to make additional authorization decisions in code. For more information, see Use a built-in authorization policy.

Configure authentication settings

These options determine how your application responds to unauthenticated requests, and the default selections will redirect all requests to sign in with this new provider. You can change customize this behavior now or adjust these settings later from the main Authentication screen by choosing Edit next to Authentication settings. To learn more about these options, see Authentication flow.

For Restrict access, decide whether to:

• Require authentication
• Allow unauthenticated access

For Unauthenticated requests

• HTTP 302 Found redirect: recommended for websites
• HTTP 401 Unauthorized: recommended for APIs
• HTTP 403 Forbidden
• HTTP 404 Not found

Select Token store (recommended). The token store collects, stores, and refreshes tokens for your application. You can disable this later if your app doesn't need tokens or you need to optimize performance.

Add the identity provider

If you selected workforce configuration, you can select Next: Permissions . These will be added to the app registration, but you can also change them later. If you selected external configuration, you can add Microsoft Graph permissions later.

Select Add.

You're now ready to use the Microsoft identity platform for authentication in your app. The provider will be listed on the Authentication screen. From there, you can edit or delete this provider configuration.

Authorize requests

By default, App Service Authentication only handles authentication, determining if the caller is who they say they are. Authorization, determining if that caller should have access to some resource, is an extra step beyond authentication. You can learn more about these concepts from Microsoft identity platform authorization basics.

Your app can make authorization decisions in code. App Service Authentication does provide some built-in checks, which can help, but they may not alone be sufficient to cover the authorization needs of your app.

Perform validations from application code

When you perform authorization checks in your app code, you can use the claims information that App Service Authentication makes available. The injected x-ms-client-principal header contains a Base64-encoded JSON object with the claims asserted about the caller. By default, these claims go through a claims mapping, so the claim names may not always match what you would see in the token. For example, the tid claim is mapped to http://schemas.microsoft.com/identity/claims/tenantid instead.

You can also work directly with the underlying access token from the injected x-ms-token-aad-access-token header.

Use a built-in authorization policy

The created app registration authenticates incoming requests for your Microsoft Entra tenant. By default, it also lets anyone within the tenant to access the application, which is fine for many applications. However, some applications need to restrict access further by making authorization decisions. Your application code is often the best place to handle custom authorization logic. However, for common scenarios, the Microsoft identity platform provides built-in checks that you can use to limit access.

This section shows how to enable built-in checks using the App Service authentication V2 API. Currently, the only way to configure these built-in checks is via Azure Resource Manager templates or the REST API.

Within the API object, the Microsoft Entra identity provider configuration has a validation section that can include a defaultAuthorizationPolicy object as in the following structure:

{
    "validation": {
        "defaultAuthorizationPolicy": {
            "allowedApplications": [],
            "allowedPrincipals": {
                "identities": []
            }
        }
    }
}

Property	Description
defaultAuthorizationPolicy	A grouping of requirements that must be met in order to access the app. Access is granted based on a logical AND over each of its configured properties. When allowedApplications and allowedPrincipals are both configured, the incoming request must satisfy both requirements in order to be accepted.
allowedApplications	An allowlist of string application client IDs representing the client resource that is calling into the app. When this property is configured as a nonempty array, only tokens obtained by an application specified in the list will be accepted. This policy evaluates the appid or azp claim of the incoming token, which must be an access token. See the Microsoft identity platform claims reference.
allowedPrincipals	A grouping of checks that determine if the principal represented by the incoming request may access the app. Satisfaction of allowedPrincipals is based on a logical OR over its configured properties.
identities (under allowedPrincipals)	An allowlist of string object IDs representing users or applications that have access. When this property is configured as a nonempty array, the allowedPrincipals requirement can be satisfied if the user or application represented by the request is specified in the list. There's a limit of 500 characters total across the list of identities. This policy evaluates the oid claim of the incoming token. See the Microsoft identity platform claims reference.

Additionally, some checks can be configured through an application setting, regardless of the API version being used. The WEBSITE_AUTH_AAD_ALLOWED_TENANTS application setting can be configured with a comma-separated list of up to 10 tenant IDs (for example, "aaaabbbb-0000-cccc-1111-dddd2222eeee") to require that the incoming token is from one of the specified tenants, as specified by the tid claim. The WEBSITE_AUTH_AAD_REQUIRE_CLIENT_SERVICE_PRINCIPAL application setting can be configured to "true" or "1" to require the incoming token to include an oid claim. This setting is ignored and treated as true if allowedPrincipals.identities has been configured (since the oid claim is checked against this provided list of identities).

Requests that fail these built-in checks are given an HTTP 403 Forbidden response.

Configure client apps to access your App Service

In the prior sections, you registered your App Service or Azure Function to authenticate users. This section explains how to register native clients or daemon apps in Microsoft Entra so that they can request access to APIs exposed by your App Service on behalf of users or themselves, such as in an N-tier architecture. Completing the steps in this section isn't required if you only wish to authenticate users.

Native client application

You can register native clients to request access your App Service app's APIs on behalf of a signed in user.

1. From the portal menu, select Microsoft Entra.

2. From the left navigation, select App registrations > New registration.

3. In the Register an application page, enter a Name for your app registration.

4. In Redirect URI, select Public client (mobile & desktop) and type the URL <app-url>/.auth/login/aad/callback. For example, https://contoso.chinacloudsites.cn/.auth/login/aad/callback.

5. Select Register.

6. After the app registration is created, copy the value of Application (client) ID.

   Note

   For a Microsoft Store application, use the package SID as the URI instead.

7. From the left navigation, select API permissions > Add a permission > My APIs.

8. Select the app registration you created earlier for your App Service app. If you don't see the app registration, make sure that you've added the user_impersonation scope in the app registration.

9. Under Delegated permissions, select user_impersonation, and then select Add permissions.

You have now configured a native client application that can request access your App Service app on behalf of a user.

Daemon client application (service-to-service calls)

In an N-tier architecture, your client application can acquire a token to call an App Service or Function app on behalf of the client app itself (not on behalf of a user). This scenario is useful for non-interactive daemon applications that perform tasks without a logged in user. It uses the standard OAuth 2.0 client credentials grant.

1. From the portal menu, select Microsoft Entra.
2. From the left navigation, select App registrations > New registration.
3. In the Register an application page, enter a Name for your app registration.
4. For a daemon application, you don't need a Redirect URI so you can keep that empty.
5. Select Register.
6. After the app registration is created, copy the value of Application (client) ID.
7. From the left navigation, select Certificates & secrets > Client secrets > New client secret.
8. Enter a description and expiration and select Add.
9. In the Value field, copy the client secret value. It won't be shown again once you navigate away from this page.

You can now request an access token using the client ID and client secret by setting the resource parameter to the Application ID URI of the target app. The resulting access token can then be presented to the target app using the standard OAuth 2.0 Authorization header, and App Service authentication will validate and use the token as usual to now indicate that the caller (an application in this case, not a user) is authenticated.

At present, this allows any client application in your Microsoft Entra tenant to request an access token and authenticate to the target app. If you also want to enforce authorization to allow only certain client applications, you must perform some extra configuration.

1. Define an App Role in the manifest of the app registration representing the App Service or Function app you want to protect.
2. On the app registration representing the client that needs to be authorized, select API permissions > Add a permission > My APIs.
3. Select the app registration you created earlier. If you don't see the app registration, make sure that you've added an App Role.
4. Under Application permissions, select the App Role you created earlier, and then select Add permissions.
5. Make sure to select Grant admin consent to authorize the client application to request the permission.
6. Similar to the previous scenario (before any roles were added), you can now request an access token for the same target resource, and the access token will include a roles claim containing the App Roles that were authorized for the client application.
7. Within the target App Service or Function app code, you can now validate that the expected roles are present in the token (this isn't performed by App Service authentication). For more information, see Access user claims.

You have now configured a daemon client application that can access your App Service app using its own identity.

Best practices

Regardless of the configuration you use to set up authentication, the following best practices keep your tenant and applications more secure:

• Configure each App Service app with its own app registration in Microsoft Entra.
• Give each App Service app its own permissions and consent.
• Avoid permission sharing between environments by using separate app registrations for separate deployment slots. When you're testing new code, this practice can help prevent issues from affecting the production app.

Next steps

• App Service Authentication / Authorization overview.
• Advanced usage of authentication and authorization in Azure App Service

• Tutorial: Authenticate and authorize users in a web app that accesses Azure Storage and Azure Graph