Azure Functions Tools for Visual Studio

Azure Functions Tools for Visual Studio 2017 is an extension for Visual Studio that lets you develop, test, and deploy C# functions to Azure. If this is your first experience with Azure Functions, you can learn more at An introduction to Azure Functions.

The Azure Functions Tools provides the following benefits:

  • Edit, build, and run functions on your local development computer.
  • Publish your Azure Functions project directly to Azure.
  • Use WebJobs attributes to declare function bindings directly in the C# code instead of maintaining a separate function.json for binding definitions.
  • Develop and deploy pre-compiled C# functions. Pre-complied functions provide a better cold-start performance than C# script-based functions.
  • Code your functions in C# while having all of the benefits of Visual Studio development.

This topic shows you how to use the Azure Functions Tools for Visual Studio 2017 to develop your functions in C#. You also learn how to publish your project to Azure as a .NET assembly.

Prerequisites

Azure Functions Tools is included in the Azure development workload of Visual Studio 2017 version 15.4, or a later version. Make sure you include the Azure development workload in your Visual Studio 2017 installation:

Install Visual Studio 2017 with the Azure development workload

To create and deploy functions, you also need:

  • An active Azure subscription. If you don't have an Azure subscription, free accounts are available.

  • An Azure Storage account. To create a storage account, see Create a storage account.

    Create an Azure Functions project

The Azure Functions project template in Visual Studio creates a project that can be published to a function app in Azure. A function app lets you group functions as a logic unit for easier management, deployment, and sharing of resources.

  1. Right mouse click on the project node in Solution Explorer, then choose Add > New Item. Choose Azure Function from the dialog box.

  2. In the New Project dialog, expand Visual C# > Cloud node, select Azure Functions, type a Name for your project, and click OK. The function app name must be valid as a C# namespace, so don't use underscores, hyphens, or any other nonalphanumeric characters.

    New project dialog to create a function in Visual Studio

Configure the project for local development

When you create a new project using the Azure Functions template, you get an empty C# project that contains the following files:

  • host.json: Lets you configure the Functions host. These settings apply both when running locally and in Azure. For more information, see host.json reference.

  • local.settings.json: Maintains settings used when running functions locally. These settings are not used by Azure, they are used by the Azure Functions Core Tools. Use this file to specify settings, such as connection strings to other Azure services. Add a new key to the Values array for each connection required by functions in your project. For more information, see Local settings file in the Azure Functions Core Tools topic.

The Functions runtime uses an Azure Storage account internally. For all trigger types other than HTTP and webhooks, you must set the Values.AzureWebJobsStorage key to a valid Azure Storage account connection string.

Note

Use of the Azure Storage Emulator is not supported by Azure Functions tools when developing locally.

To set the storage account connection string:

  1. In Visual Studio, open Cloud Explorer, expand Storage Account > Your Storage Account, then select Properties and copy the Primary Connection String value.

  2. In your project, open the local.settings.json project file and set the value of the AzureWebJobsStorage key to the connection string you copied.

  3. Repeat the previous step to add unique keys to the Values array for any other connections required by your functions.

Create a function

In pre-compiled functions, the bindings used by the function are defined by applying attributes in the code. When you use the Azure Functions Tools to create your functions from the provided templates, these attributes are applied for you.

  1. In Solution Explorer, right-click on your project node and select Add > New Item. Select Azure Function, type a Name for the class, and click Add.

  2. Choose your trigger, set the binding properties, and click Create. The following example shows the settings when creating a Queue storage triggered function.

    A connection string key named QueueStorage is supplied, which is defined in the local.settings.json file.

  3. Examine the newly added class. You see a static Run method, that is attributed with the FunctionName attribute. This attribute indicates that the method is the entry point for the function.

    For example, the following C# class represents a basic Queue storage triggered function:

    using System;
    using Microsoft.Azure.WebJobs;
    using Microsoft.Azure.WebJobs.Host;
    
    namespace FunctionApp1
    {
        public static class Function1
        {
            [FunctionName("QueueTriggerCSharp")]        
            public static void Run([QueueTrigger("myqueue-items", Connection = "QueueStorage")]string myQueueItem, TraceWriter log)
            {
                log.Info($"C# Queue trigger function processed: {myQueueItem}");
            }
        }
    } 
    

    A binding-specific attribute is applied to each binding parameter supplied to the entry point method. The attribute takes the binding information as parameters. In the previous example, the first parameter has a QueueTrigger attribute applied, indicating queue triggered function. The queue name and connection string setting name are passed as parameters.

Testing functions

Azure Functions Core Tools lets you run Azure Functions project on your local development computer. You are prompted to install these tools the first time you start a function from Visual Studio.

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

With the project running, you can test your code as you would test deployed function. For more information, see Strategies for testing your code in Azure Functions. When running in debug mode, breakpoints are hit in Visual Studio as expected.

For an example of how to test a queue triggered function, see the queue triggered function quickstart tutorial.

To learn more about using the Azure Functions Core Tools, see Code and test Azure functions locally.

Publish to Azure

  1. In Solution Explorer, right-click the project and select Publish. Choose Create New and then click Publish.

    Publish create new function app

  2. If you haven't already connected Visual Studio to your Azure account, click Add an account....

  3. In the Create App Service dialog, use the Hosting settings as specified in the following table:

    Azure local runtime

    Setting Suggested value Description
    App Name Globally unique name Name that uniquely identifies your new function app.
    Subscription Choose your subscription The Azure subscription to use.
    Resource Group myResourceGroup Name of the resource group in which to create your function app.
    App Service Plan Consumption plan Make sure to choose the Consumption under Size when you create a new plan.
    Storage account Globally unique name Use an existing storage account or create a new one.
  4. Click Create to create a function app in Azure with these settings. After the provisioning is complete, make a note of the Site URL value, which is the address of your function app in Azure.

    Azure local runtime

Note

Any settings you added in the local.settings.json must be also added to the function app in Azure. These settings are not added automatically. You can add required settings to your function app in one of these ways:

Next steps

For more information about Azure Functions Tools, see the Common Questions section of the Visual Studio 2017 Tools for Azure Functions blog post.

To learn more about the Azure Functions Core Tools, see Code and test Azure functions locally.
To learn more about developing functions as .NET class libraries, see Using .NET class libraries with Azure Functions. This topic also provides examples of how to use attributes to declare the various types of bindings supported by Azure Functions.