Azure Functions .NET 5 support

Welcome to a preview of .NET 5 in Azure Functions. .NET 5 functions run in an out-of-process language worker that is separate from the Azure Functions runtime. This allows you to have full control over your application's dependencies as well as other new features like a middleware pipeline.

A .NET 5 function app works differently than a .NET Core 3.1 function app. For .NET 5, you build an executable that imports the .NET 5 language worker as a NuGet package. Your app includes a Program.cs that starts the worker.

If you've built .NET Core 3.1 Azure Functions before, the rest of a .NET 5 Azure Functions app should look quite familiar. Refer to the information in this README for how to get started and for more details about the main differences.

As this is a preview, there may be some breaking changes to be expected.

How to run the sample

Install .NET 5.0

Download .NET 5.0 from here

Install the Azure Functions Core Tools

Please make sure you have Azure Functions Core Tools >= 3.0.3160.

To download, please check out our docs at Azure Functions Core Tools

FunctionApp folder structure

Here are the important artifacts in a .NET 5 Azure Functions app (FunctionApp folder).

local.settings.json

{
  "IsEncrypted": false,
  "Values": {
    "FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated",
    "AzureWebJobsStorage": ""
  }
}

FUNCTIONS_WORKER_RUNTIME - Set this to a value of dotnet-isolated. This is likely to change in the future as this worker is intended for future .NET versions as well.
AzureWebJobsStorage - Some of the functions in the sample require a Storage account. Set the value of AzureWebJobsStorage to the connection string to a valid Storage account or running Storage Emulator.

FunctionApp.csproj

There are some main differences between a .NET 5 Azure Functions project compared to .NET Core 3.1.

TargetFramework and OutputType - A .NET 5 Azure Functions app is a .NET 5 executable (console app) that runs in a process that is separate from the Azure Functions host.
AzureFunctionsVersion - .NET 5 Azure Functions still uses the v3 Azure Functions host.
_FunctionsSkipCleanOutput - Ensure this is set to prevent the build process from removing important files in the output.

<PropertyGroup>
  <TargetFramework>net5.0</TargetFramework>
  <LangVersion>preview</LangVersion>
  <AzureFunctionsVersion>v3</AzureFunctionsVersion>
  <OutputType>Exe</OutputType>
  <_FunctionsSkipCleanOutput>true</_FunctionsSkipCleanOutput>
</PropertyGroup>

Also note the package references needed for the .NET 5 worker. You can use other .NET 5 compatible packages in your project.

For functions attributes to work, you also need to reference the appropriate WebJobs SDK packages that contain the required types.

Functions

Like .NET Core 3.1 function apps, functions are in C# files. They are currently separated into folders but, like .NET Core 3.1 functions, they can be organized differently if you wish.

One important difference with .NET 5 functions is that "rich bindings", such as Durable Functions or binding to SDK types like Cosmos DB client, are not supported. Use strings and C# objects (POCOs). For HTTP, use HttpRequestData and HttpResponseData objects.

Function1 - An HTTP trigger with a Blob input and a Queue output.
Function2 - A Queue trigger with a Blob input.
Function3 - An HTTP trigger with a Queue output.
Function4 - A simple HTTP trigger.
Function5 - An HTTP triggered function that demonstrates dependency injection.

Middleware

The Azure Functions .NET Worker supports middleware registration, following a model similar to what exists in ASP.NET and giving you the ability to inject logic into the invocation pipeline, pre and post function executions.

While the full middleware registration set of APIs is not yet exposed, middleware registration is supported and we've added an example to the sample application under the Middleware folder.

Run the sample locally

In the FunctionApp folder, run func host start [Optional --verbose]. This will preform a build and then run the host.

cd FunctionApp
func host start --verbose

Attaching the debugger

VS Code

Ensure version 1.1.0 or later of the Azure Functions VS Code extension is installed and you have this repo open at the root. In the "Run" icon in the Activity Bar, select the Attach to .NET Functions launch task and click the "Start Debugging" button or press F5. The app will start and the debugger will attach.

Visual Studio

To debug in Visual Studio, uncomment the Debugger.Launch() statements in Program.cs. The process will attempt to launch a debugger before continuing.

YOU CAN NOT DEBUG DIRECTLY USING "Start Debugging" IN VISUAL STUDIO DIRECTLY. You need to use the command line as mentioned in the previous Run the sample locally part of this readme.

We're working with the Visual Studio team to provide an integrated debugging experience.

Deploying to Azure

Create the Azure resources

To deploy the app, first ensure that you've installed the Azure CLI.
Login to the CLI.
```
az login
```
If necessary, use az account set to select the subscription you want to use.

Create a resource group, Storage account, and Azure Functions app.

az group create --name AzureFunctionsQuickstart-rg --location westeurope
az storage account create --name <STORAGE_NAME> --location westeurope --resource-group AzureFunctionsQuickstart-rg --sku Standard_LRS
az functionapp create --resource-group AzureFunctionsQuickstart-rg --consumption-plan-location westeurope --runtime dotnet --functions-version 3 --name <APP_NAME> --storage-account <STORAGE_NAME>

Deploy the app

Ensure you're in your functions project (FunctionApp) folder.
Publish the .NET project.
```
dotnet publish -c Release
```
Cd into the publish artifacts.
```
cd ./bin/Release/net5.0/publish
```

Deploy the app.

func azure functionapp publish <APP_NAME>

Known issues

Deployment to Azure is currently limited to Windows plans. Note that some optimizations are not in place in the consumption plan and you may experience longer cold starts.

Feedback

Please create issues in this repo. Thanks!

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.opensource.microsoft.com.

When you submit a pull request, a CLA bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., status check, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.

Trademarks

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Snijderman/azure-functions-dotnet-worker-preview