Calling a web API in an ASP.NET Core web application using Azure AD

Senast uppdaterad: 2018-02-21
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About this sample

Scenario

This sample contains a web API running on ASP.NET Core 2.0 protected by Azure AD. The web API is accessed by an ASP.NET Core 2.0 web application on behalf of the signed-in user. The ASP.NET Web application uses the OpenID Connect middleware and the Active Directory Authentication Library (ADAL.NET) to obtain a JWT bearer token for the signed-in user using the OAuth 2.0 protocol. The bearer token is passed to the web API, which validates the token and authorizes the user using the JWT bearer authentication middleware.

More information

For more information about how the protocols work in this scenario and other scenarios, see Authentication Scenarios for Azure AD.

This sample has been updated to ASP.NET Core 2.0. Looking for previous versions of this code sample? Check out the tags on the ASP.NET Core 1.0 branch.

User experience

The web API, TodoListService, maintains an in-memory collection of to-do items per authenticated user. The authenticated user carries the same to-do list across multiple instances of the web app in this sample as well as native clients like the .NET native (WPF) client.

The ASP.NET Core 2.0 web app, TodoListWebApp enables a user to: - Sign in. The first time a user signs in, a consent screen prompts the user for permission to access TodoListService and obtain user profile information from Azure Active Directory. Since this is a web app, hosted in a browser, it can be that the user gets immediately signed-in benefiting from Single Sign On with other web applications. - Select Todo List in the app's navigation bar. The user may then: - See the list of to-do items exposed by Web API for the signed-in identity, - Add more to-do items (buy clicking on Add item). - Sign out.

On subsequent returns to the web app, the user's session is persisted locally in a cookie and reauthentication is not required.

Running the sample

[!NOTE] If you want to run this sample on Azure Government, see the "Azure Government Deviations" section at the bottom of this page.

Pre-requisites

Step 1: Clone or download this repository

From your shell or command line:

git clone https://github.com/Azure-Samples/active-directory-dotnet-webapp-webapi-openidconnect-aspnetcore.git

Step 2: Register the sample with the Azure Active Directory tenant

There are two projects in this sample. Each needs to be registered in your Azure AD tenant.

Register the TodoListService web API

  1. Sign in to the Azure portal.
  2. On the top bar, click on the signed-in account. Under Directory, select the Azure AD tenant where the app will be registered.
  3. In the navigation on the left, select More Services >. Scroll down and select Azure Active Directory.
  4. Select App registrations and then select + New application registration.
  5. Enter TodoListService for Name. For Application type, select *Web app / API'. For Sign-on URL, enter the base URL for the sample web API project (by default https://localhost:44351). Select the Create button to create the app registration.
  6. From the list of app registrations, select the newly created application, select Settings, and then select Properties. Note the following information for reference in later steps:
    • The domain of the Azure AD tenant in App ID URI. Only the domain, such as contoso.onmicrosoft.com is required. Omit the rest of the URI.
    • Application ID
  7. Return to the list of app registrations. Select the Endpoints button. Note the GUID (formatted xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx) from any of the endpoint URLs. This is the Tenant ID. Omit the rest of the URL.

[!NOTE] By default, the list of app registrations is filtered to My apps. To see the app that was just registered, select All apps. in the filter dropdown near the top of the blade.

Register the TodoListWebApp web application

  1. Return to the list of app registrations. Select + New application registration.
  2. Enter TodoListWebApp for Name. For Application type, select Web app / API. For Sign-on URL, enter the base URL for the sample web app project (by default http://localhost:17945/signin-oidc). Select the Create button to create the app registration.
  3. From the list of app registrations, select the newly created application, select Settings, and then select Properties. Note the Application ID for reference in later steps.
  4. On the same blade, set the Logout Url property to https://localhost:44371/Account/EndSession. Select Save.
  5. From the Settings blade, select Keys. Add a new key by entering a key description and duration of either 1 year or 2 years. Select Save. Note the displayed key value for later steps. Be sure the key value is copied correctly, as it is will not be displayed again. Should the key value be lost, a new key must be created.
  6. From the Settings blade, select Required permissions. Select + Add, and then select Select an API. Type TodoListService in the textbox and press Enter. Select the web API from the list and then select the Select button. Select Select Permissions. Tick the checkbox next to Access TodoListService and then select the Select button. Select the Done button.

Step 3: Configure the sample to use the Azure AD tenant

Configure the TodoListService project

  1. Open the solution in Visual Studio.
  2. In the TodoListService project, open the appsettings.json file.
  3. Find the Domain property and replace the value with the AAD tenant domain.
  4. Find the TenantId property and replace the value with the Tenant ID.
  5. Find the ClientId property and replace the value with the Application ID property of the TodoListService application.

Configure the TodoListWebApp project

[!WARNING] Follow these steps carefully. The Application ID property of both app registrations are used below.

  1. In the TodoListWebApp project, open the appsettings.json file.
  2. Find the Domain property and replace the value with the AAD tenant domain.
  3. Find the TenantId property and replace the value with the Tenant ID.
  4. Find the ClientId property and replace the value with the Application ID of the TodoListWebApp app.
  5. Find the ClientSecret and replace the value with the key value for the TodoListWebApp app.
  6. Find the TodoListResourceId property and replace the value with the Application ID of the TodoListService app

Step 4: Run the sample

In the solution properties, set both projects as startup projects. Set TodoListService to run first. Clean the solution, rebuild it, and then run it.

On startup, the web API displays an empty web page. This is expected behavior.

Explore the sample by signing in into the web app, clicking on "Todo List", signing again if needed, adding items to the To Do list, signing-out, and starting again. Since the authenticated session is stored in a cookie, the application doesn't require logging in again if the previous session was never signed out.

[!NOTE] The To Do list is stored in memory in this sample. Each time the TodoListService API is stopped, any to-do lists are reset.

How the code was created?

Code for the service

The code for the service is exactly the same as the service used in the active-directory-dotnet-native-aspnetcore sample. Please refer to that sample for more information.

Code for ASP.NET Web App

The code for the ASP.NET web app is based on the code of the active-directory-dotnet-webapp-openidconnect-aspnetcore sample. Please read the "About The code" section of that sample first.

Then, based on that code, the following modifications were applied. This commit details the incremental changes described below: - Update of the AzureAdOptions class to add a property to compute the Authority from the instance and the tenantID, and adding two other configuration options for ClientSecret, the resourceId of TodoListService (its clientId) and the base address for this service. - Added a TodoListItem in models to deserialize the Json sent by the TodoListService - Added a NaiveSessionCache class in a new Utils folder which serves as a token cache which livetime is the duration of the session. Updated the Startup.cs file accordingly to add sessions. - Added a TodoListController and a Todo view, as well as a "Todo List" entry in the toolbar of the Web API. This is where most of the interesting code is - Updated the SignOut() method of the AccountController to clear the cache for the user when s/he signs-out. - Updated AzureAdAuthenticationBuilderExtensions.cs to request an authorization code, and redeem it, getting an access token to the Azure AD graph (https://graph.windows.com), so that the token cache contains a token for the user. This token will be used by the TodoController to request another token for the TodoListService

This scenario is slightly different than the same scenario in ASP.NET (not Core). Note the following line in AzureAdAuthenticationBuilderExtensions.cs:

options.ResponseType = "id_token code";

Unlike ASP.NET, ASP.NET Core 2.0 uses an implicit flow by default. Without overriding the response type (default id_token), the OnTokenValidated event is fired instead of OnAuthorizationCodeReceived. The line above requests both id_token and code, so that OnTokenValidated is called first. This ensures that context.Principal has a non-null value representing the signed-in user when OnAuthorizeationCodeReceived is called.

How to change the app URL

If you are using Visual Studio 2017 1. Edit the TodoListService's properties (right click on TodoListService.csproj, and choose Properties) 1. In the Debug tab: 1. Check the Launch browser field to https://localhost:44351/api/todolist 1. Change the App URL field to be https://localhost:44351 as this is the URL registered in the Azure AD application representing our Web API. 1. Check the Enable SSL field

The same kind of modifications can be made on the TodoListWebApp.csproj project.

[!WARNING] Ensure that all of the app registration steps reflect any changes made to the URLs, or the sample won't function.

What to change when you deploy the sample to Azure

To this sample to Azure: - Update the various URLs (reply URLs, Base URL) in the appsettings.json files - Add Reply URLs pointing to the deployed location, for both applications in the Azure portal

Azure Government Deviations

In order to run this sample on Azure Government you can follow through the steps above with a few variations:

  • Step 2:
    • You must register this sample for your AAD Tenant in Azure Government by following Step 2 above in the Azure Government portal.
  • Step 3:
    • Before configuring the sample, you must make sure your Visual Studio is connected to Azure Government.
    • Navigate to the appsettings.json files for both the TodoListService web API and TodoListWebApp web application. Replace the "Instance" property in the Azure AD section with https://login.microsoftonline.us/.

Once those changes have been accounted for, you should be able to run this sample on Azure Government.

Related content

Other documentation / samples

The scenarios involving Azure Active directory with ASP.NET Core are described in ASP.Net Core | Security | Authentication | Azure Active Directory. From this page, you can access the related samples