quickstart-feature-flag-dotnet.md

title	description	services	documentationcenter	author	editor	ms.assetid	ms.service	ms.devlang	ms.custom	ms.topic	ms.tgt_pltfrm	ms.workload	ms.date	ms.author
Quickstart for adding feature flags to .NET Framework apps | Microsoft Docs | Microsoft Docs	A quickstart for adding feature flags to .NET Framework apps and managing them in Azure App Configuration	azure-app-configuration		AlexandraKemperMS			azure-app-configuration	csharp	devx-track-csharp, mode-other	quickstart	.NET	tbd	10/19/2020	alkemper

Quickstart: Add feature flags to a .NET Framework app

In this quickstart, you incorporate Azure App Configuration into a .NET Framework app to create an end-to-end implementation of feature management. You can use the App Configuration service to centrally store all your feature flags and control their states.

The .NET Feature Management libraries extend the framework with feature flag support. These libraries are built on top of the .NET configuration system. They integrate with App Configuration through its .NET configuration provider.

Prerequisites

• Azure subscription - create one for free
• Visual Studio 2019
• .NET Framework 4.8

Create an App Configuration store

[!INCLUDE azure-app-configuration-create]

7. Select Feature Manager > +Add to add a feature flag called Beta.

   [!div class="mx-imgBorder"]

   Leave label undefined for now.

Create a .NET console app

1. Start Visual Studio, and select File > New > Project.

2. In Create a new project, filter on the Console project type and click on Console App (.NET Framework). Click Next.

3. In Configure your new project, enter a project name. Under Framework, select .NET Framework 4.8 or higher. Click Create.

Connect to an App Configuration store

1. Right-click your project, and select Manage NuGet Packages. On the Browse tab, search and add the following NuGet packages to your project.

   Microsoft.Extensions.DependencyInjection
   Microsoft.Extensions.Configuration.AzureAppConfiguration
   Microsoft.FeatureManagement
   

2. Open Program.cs and add the following statements:

   using Microsoft.Extensions.DependencyInjection;
   using Microsoft.Extensions.Configuration;
   using Microsoft.Extensions.Configuration.AzureAppConfiguration;
   using Microsoft.FeatureManagement;
   using System.Threading.Tasks;

3. Update the Main method to connect to App Configuration, specifying the UseFeatureFlags option so that feature flags are retrieved. Then display a message if the Beta feature flag is enabled.

       public static async Task Main(string[] args)
       {         
           IConfigurationRoot configuration = new ConfigurationBuilder()
               .AddAzureAppConfiguration(options =>
               {
                   options.Connect(Environment.GetEnvironmentVariable("ConnectionString"))
                          .UseFeatureFlags();
               }).Build();
   
           IServiceCollection services = new ServiceCollection();
   
           services.AddSingleton<IConfiguration>(configuration).AddFeatureManagement();
   
           using (ServiceProvider serviceProvider = services.BuildServiceProvider())
           {
               IFeatureManager featureManager = serviceProvider.GetRequiredService<IFeatureManager>();
   
               if (await featureManager.IsEnabledAsync("Beta"))
               {
                   Console.WriteLine("Welcome to the beta!");
               }
           }
   
           Console.WriteLine("Hello World!");
           Console.WriteLine("Press any key to continue ...");
           Console.Read();
       }

Build and run the app locally

1. Set an environment variable named ConnectionString to the connection string of your App Configuration store. If you use the Windows command prompt, run the following command:

       setx ConnectionString "connection-string-of-your-app-configuration-store"

   If you use Windows PowerShell, run the following command:

       $Env:ConnectionString = "connection-string-of-your-app-configuration-store"

2. Restart Visual Studio to allow the change to take effect.

3. Press Ctrl + F5 to build and run the console app.

   

Clean up resources

[!INCLUDE azure-app-configuration-cleanup]

Next steps

In this quickstart, you created a feature flag in App Configuration and used it with a .NET Framework console app. To learn how to dynamically update feature flags and other configuration values without restarting the application, continue to the next tutorial.

[!div class="nextstepaction"] Enable dynamic configuration