quickstart-azure-functions-csharp.md

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Quickstart for Azure App Configuration with Azure Functions | Microsoft Docs	In this quickstart, make an Azure Functions app with Azure App Configuration and C#. Create and connect to an App Configuration store. Test the function locally.	azure-app-configuration	zhenlan	azure-app-configuration	csharp	devx-track-csharp, mode-other	quickstart	03/20/2023	zhenlwa

Quickstart: Create an Azure Functions app with Azure App Configuration

In this quickstart, you incorporate the Azure App Configuration service into an Azure Functions app to centralize storage and management of all your application settings separate from your code.

Prerequisites

• An Azure account with an active subscription. Create one for free.
• An App Configuration store. Create a store.
• Visual Studio with the Azure development workload.
• Azure Functions tools, if you don't have it installed with Visual Studio already.

Add a key-value

Add the following key-value to the App Configuration store and leave Label and Content Type with their default values. For more information about how to add key-values to a store using the Azure portal or the CLI, go to Create a key-value.

Key	Value
TestApp:Settings:Message	Data from Azure App Configuration

Create a Functions app

[!INCLUDE Create a project using the Azure Functions template]

Connect to an App Configuration store

This project will use dependency injection in .NET Azure Functions and add Azure App Configuration as an extra configuration source. Azure Functions support running in-process or isolated-process. Pick the one that matches your requirements.

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

   In-process

   • Microsoft.Extensions.Configuration.AzureAppConfiguration version 4.1.0 or later
   • Microsoft.Azure.Functions.Extensions version 1.1.0 or later

   Isolated process

   • Microsoft.Azure.AppConfiguration.Functions.Worker

   ---

2. Add code to connect to Azure App Configuration.

   In-process

   Add a new file, Startup.cs, with the following code. It defines a class named Startup that implements the FunctionsStartup abstract class. An assembly attribute is used to specify the type name used during Azure Functions startup.

   The ConfigureAppConfiguration method is overridden and Azure App Configuration provider is added as an extra configuration source by calling AddAzureAppConfiguration(). The Configure method is left empty as you don't need to register any services at this point.

   using System;
   using Microsoft.Azure.Functions.Extensions.DependencyInjection;
   using Microsoft.Extensions.Configuration;
   
   [assembly: FunctionsStartup(typeof(FunctionApp.Startup))]
   
   namespace FunctionApp
   {
       class Startup : FunctionsStartup
       {
           public override void ConfigureAppConfiguration(IFunctionsConfigurationBuilder builder)
           {
               string cs = Environment.GetEnvironmentVariable("ConnectionString");
               builder.ConfigurationBuilder.AddAzureAppConfiguration(cs);
           }
   
           public override void Configure(IFunctionsHostBuilder builder)
           {
           }
       }
   }

   Isolated process

   Open Program.cs and update the Main() method as following. You add Azure App Configuration provider as an extra configuration source by calling AddAzureAppConfiguration().

   public static void Main()
   {
       var host = new HostBuilder()
           .ConfigureAppConfiguration(builder =>
           {
               string cs = Environment.GetEnvironmentVariable("ConnectionString");
               builder.AddAzureAppConfiguration(cs);
           })
           .ConfigureFunctionsWorkerDefaults()
           .Build();
   
       host.Run();
   }

   ---

3. Open Function1.cs, and add the following namespace if it's not present already.

   using Microsoft.Extensions.Configuration;

   Add or update the constructor used to obtain an instance of IConfiguration through dependency injection.

   In-process

   private readonly IConfiguration _configuration;
   
   public Function1(IConfiguration configuration)
   {
       _configuration = configuration;
   }

   Isolated process

   private readonly IConfiguration _configuration;
   
   public Function1(ILoggerFactory loggerFactory, IConfiguration configuration)
   {
       _logger = loggerFactory.CreateLogger<Function1>();
       _configuration = configuration;
   }

   ---

4. Update the Run method to read values from the configuration.

   In-process

   [FunctionName("Function1")]
   public async Task<IActionResult> Run(
       [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = null)] HttpRequest req, ILogger log)
   {
       log.LogInformation("C# HTTP trigger function processed a request.");
   
       // Read configuration data
       string keyName = "TestApp:Settings:Message";
       string message = _configuration[keyName];
   
       return message != null
           ? (ActionResult)new OkObjectResult(message)
           : new BadRequestObjectResult($"Please create a key-value with the key '{keyName}' in App Configuration.");
   }

   [!NOTE] The Function1 class and the Run method should not be static. Remove the static modifier if it was autogenerated.

   Isolated process

   [Function("Function1")]
   public HttpResponseData Run([HttpTrigger(AuthorizationLevel.Anonymous, "get", "post")] HttpRequestData req)
   {
       _logger.LogInformation("C# HTTP trigger function processed a request.");
   
       var response = req.CreateResponse(HttpStatusCode.OK);
       response.Headers.Add("Content-Type", "text/plain; charset=utf-8");
   
       // Read configuration data
       string keyName = "TestApp:Settings:Message";
       string message = _configuration[keyName];
   
       response.WriteString(message ?? $"Please create a key-value with the key '{keyName}' in Azure App Configuration.");
   
       return response;
   }

   ---

Test the function locally

1. Set an environment variable named ConnectionString, and set it to the access key to your App Configuration store.

   If you use the Windows command prompt, run the following command and restart the command prompt to allow the change to take effect:

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

   If you use PowerShell, run the following command:

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

   If you use macOS or Linux, run the following command:

   export ConnectionString='connection-string-of-your-app-configuration-store'

2. Press F5 to test your function. If prompted, accept the request from Visual Studio to download and install Azure Functions Core (CLI) tools. You might also need to enable a firewall exception so that the tools can handle HTTP requests.

3. Copy the URL of your function from the Azure Functions runtime output.

   

4. Paste the URL for the HTTP request into your browser's address bar. The following image shows the response in the browser to the local GET request returned by the function.

   

Clean up resources

[!INCLUDE azure-app-configuration-cleanup]

Next steps

In this quickstart, you created a new App Configuration store and used it with an Azure Functions app via the App Configuration provider. To learn how to update your Azure Functions app to dynamically refresh configuration, continue to the next tutorial.

[!div class="nextstepaction"] Enable dynamic configuration in Azure Functions

To learn how to use an Azure managed identity to streamline the access to App Configuration, continue to the next tutorial.

[!div class="nextstepaction"] Access App Configuration using managed identity