Integrating NuGet Packages into Azure Functions

Azure Functions provide a powerful, serverless environment for executing code in response to various triggers. One common need when developing these functions is the ability to use external libraries, typically managed as NuGet packages. This post explains how to integrate NuGet packages into your Azure Functions, ensuring you can leverage external libraries effectively in your serverless computing solutions.

Using NuGet Packages in Azure Functions V1

For Azure Functions V1, you need to create a project.json file to manage NuGet dependencies. Here’s how you can add external libraries to your function:

Step-by-Step Guide

1. Create a project.json File:
   Navigate to the Develop section of your function in the Azure portal and use the “View files” option to create or upload a project.json file.

   {
     "frameworks": {
       "net46": {
         "dependencies": {
           "Newtonsoft.Json": "12.0.3"
         }
       }
     }
   }
   

2. Automatic Package Restore:
   Azure Functions runtime will automatically detect and restore the packages listed in project.json. This will occur without needing to explicitly add assembly references using #r "AssemblyName".

3. Write Your Function:
   Once the packages are restored, you can directly use them in your function code.

   using Newtonsoft.Json;
   
   public static async Task<IActionResult> Run(HttpRequest req, ILogger log)
   {
       string jsonContent = await new StreamReader(req.Body).ReadToEndAsync();
       var data = JsonConvert.DeserializeObject<MyModel>(jsonContent);
       // Process data
       return new OkObjectResult("Data processed");
   }
   

Handling NuGet Packages in Azure Functions V2 and Later

For Azure Functions V2 and later, project.json is replaced by a new format using a .csproj file which supports PackageReference nodes.

How to Configure

1. Create a .csproj File:
   Instead of project.json, use a .csproj file to specify your NuGet dependencies.

   <Project Sdk="Microsoft.NET.Sdk">
     <PropertyGroup>
         <TargetFramework>netcoreapp3.1</TargetFramework>
     </PropertyGroup>
     <ItemGroup>
         <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.Storage" Version="4.0.4" />
     </ItemGroup>
   </Project>
   

2. Deployment and Restoration:
   Similar to V1, the Azure Functions environment will handle the restoration of packages automatically when your function starts or updates.

3. Using the Packages in Your Function:
   After setup, the libraries from the NuGet packages can be directly utilized in your functions.

   using Microsoft.Azure.WebJobs;
   using Microsoft.Extensions.Logging;
   
   public static void Run([TimerTrigger("0 */5 * * * *")]TimerInfo myTimer, ILogger log)
   {
       log.LogInformation($"C# Timer trigger function executed at: {DateTime.Now}");
   }
   

Additional Deployment Options

Azure Functions supports several deployment mechanisms:

• Using the App Service Editor (Monaco): Directly edit your function files in the browser.
• Using SCM (Kudu) Endpoint: Deploy files via the SCM site for your function app.
• FTP Upload: Manually upload your .csproj or function files using FTP.

Integrating NuGet packages into Azure Functions allows developers to extend the functionality of their serverless applications significantly. Whether you are using V1 with project.json or V2 and later with .csproj, Azure Functions provides a flexible platform to include and manage external libraries efficiently. Remember, with serverless architectures, every bit of efficiency in your code translates directly to cost savings and performance improvements.