Quickstart: Create an Azure Functions app with Azure App Configuration

Article
03/29/2023

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

The Azure Functions project template in Visual Studio creates a C# class library project that you can publish to a function app in Azure. You can use a function app to group functions as a logical unit for easier management, deployment, scaling, and sharing of resources.

From the Visual Studio menu, select File > New > Project.
In Create a new project, enter functions in the search box, choose the Azure Functions template, and then select Next.
In Configure your new project, enter a Project name for your project, and then select Create. The function app name must be valid as a C# namespace, so don't use underscores, hyphens, or any other nonalphanumeric characters.

For the Create a new Azure Functions application settings, use the values in the following table:

Isolated worker model
In-process model

Setting	Value	Description
.NET version	.NET 6 Isolated	This value creates a function project that runs in an isolated worker process. Isolated worker process supports other non-LTS version of .NET and also .NET Framework. For more information, see Azure Functions runtime versions overview.
Function template	HTTP trigger	This value creates a function triggered by an HTTP request.
Storage account (AzureWebJobsStorage)	Storage emulator	Because a function app in Azure requires a storage account, one is assigned or created when you publish your project to Azure. An HTTP trigger doesn't use an Azure Storage account connection string; all other trigger types require a valid Azure Storage account connection string.
Authorization level	Anonymous	The created function can be triggered by any client without providing a key. This authorization setting makes it easy to test your new function. For more information about keys and authorization, see Authorization keys and HTTP and webhook bindings.

Azure Functions project settings

Important

Support will end for the in-process model on November 10, 2026. We highly recommend that you migrate your apps to the isolated worker model for full support.

Setting	Value	Description
.NET version	.NET 6	This value creates a function project that runs in-process with version 4.x of the Azure Functions runtime. For more information, see Azure Functions runtime versions overview.
Function template	HTTP trigger	This value creates a function triggered by an HTTP request.
Storage account (AzureWebJobsStorage)	Storage emulator	Because a function app in Azure requires a storage account, one is assigned or created when you publish your project to Azure. An HTTP trigger doesn't use an Azure Storage account connection string; all other trigger types require a valid Azure Storage account connection string.
Authorization level	Anonymous	The created function can be triggered by any client without providing a key. This authorization setting makes it easy to test your new function. For more information about keys and authorization, see Authorization keys and HTTP and webhook bindings.

Azure Functions project settings

Make sure you set the Authorization level to Anonymous. If you choose the default level of Function, you're required to present the function key in requests to access your function endpoint.

Select Create to create the function project and HTTP trigger function.

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.

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
- Isolated process
- Microsoft.Extensions.Configuration.AzureAppConfiguration version 4.1.0 or later
- Microsoft.Azure.Functions.Extensions version 1.1.0 or later
- Microsoft.Azure.AppConfiguration.Functions.Worker

Add code to connect to Azure App Configuration.

In-process
Isolated 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)
        {
        }
    }
}

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();
}

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
Isolated process

private readonly IConfiguration _configuration;

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

private readonly IConfiguration _configuration;

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

Update the Run method to read values from the configuration.

In-process
Isolated 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.

[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

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 Windows 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'
```
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.
Copy the URL of your function from the Azure Functions runtime output.
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

If you don't want to continue using the resources created in this article, delete the resource group you created here to avoid charges.

Important

Deleting a resource group is irreversible. The resource group and all the resources in it are permanently deleted. Ensure that you don't accidentally delete the wrong resource group or resources. If you created the resources for this article inside a resource group that contains other resources you want to keep, delete each resource individually from its respective pane instead of deleting the resource group.

Sign in to the Azure portal, and select Resource groups.
In the Filter by name box, enter the name of your resource group.
In the result list, select the resource group name to see an overview.
Select Delete resource group.
You're asked to confirm the deletion of the resource group. Enter the name of your resource group to confirm, and select Delete.

After a few moments, the resource group and all its resources are deleted.

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.

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.

Access App Configuration using managed identity

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