This library provides gRPC support for Azure Functions .NET Worker communication with the Azure Functions Host.

Install-Package Microsoft.Azure.Functions.Worker.Grpc -Version 1.3.0


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Azure Functions .NET Worker

Welcome to the Azure Functions .NET Worker Repository. The .NET Worker provides .NET 5 support in Azure Functions, introducing an Isolated Model, running as 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 Isolated function app works differently than a .NET Core 3.1 function app. For .NET Isolated, you build an executable that imports the .NET Isolated language worker as a NuGet package. Your app includes a Program.cs that starts the worker.

Binding Model

.NET Isolated introduces a new binding model, slightly different from the binding model exposed in .NET Core 3 Azure Functions. More information can be found here. Please review our samples for usage information.


The Azure Functions .NET Isolated 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.


You can find samples on how to use different features of the .NET Worker under samples (link).

Create and run .NET Isolated functions

Note: Visual Studio and Visual Studio Code support is on the way. In the meantime, please use azure-functions-core-tools or the sample projects as a starting point.

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 >= 3.0.3388.

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

Create a .NET Isolated project

In an empty directory, run func init and select dotnet (Isolated Process).

Add a function

Run func new and select any trigger (HttpTrigger is a good one to start). Fill in the function name.

Run functions locally

Run func host start in the sample app directory.

Note: If you selected a trigger different from HttpTrigger, you may need to setup local connection strings or emulator for the trigger service.

Attaching the debugger

Visual Studio

Release candidate instructions. Requires RC packages

NOTE: To debug your Worker, you must be using the Azure Functions Core Tools version 3.0.3381 or higher

In your worker directory (or your worker's build output directory), run:

func host start --dotnet-isolated-debug

Core Tools will run targeting your worker and the process will stop with the following message:

Azure Functions .NET Worker (PID: <process id>) initialized in debug mode. Waiting for debugger to attach...

Where <process id> is the ID for your worker process.

At this point, your worker process wil be paused, waiting for the debugger to be attached. You can now use Visual Studio to manually attach to the process (to learn more, see how to attach to a running process)

Once the debugger is attached, the process execution will resume and you will be able to debug.

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

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

JetBrains Rider

NOTE: To debug your Worker, you must be using the Azure Functions Core Tools version 3.0.3381 or higher. You must also have the Azure Toolkit for Rider installed.

In Rider, make sure a Run Configuration is generated for your Azure Functions project is active. You can also create a custom Run Configuration from the Run | Edit Configurations... menu.

To start debugging, select the run configuration and start debugging. This will compile your project, run the Core Tools, and attach the debugger to your project.

Under the hood, Rider launches the Core Tools with the --dotnet-isolated-debug argument, and attached to the process ID for your worker process.

You can place a breakpoint in any function, and inspect your code as it is running. Note that debugging startup code may timeout (#434).

Deploying to Azure

Create the Azure resources

  1. To deploy the app, first ensure that you've installed the Azure CLI.

  2. Login to the CLI.

    az login
  3. If necessary, use az account set to select the subscription you want to use.

  4. Create a resource group, Storage account, and Azure Functions app. If you would like to use an existing Windows .NET Core 3 function app, please skip this step.

    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-isolated --functions-version 3 --name <APP_NAME> --storage-account <STORAGE_NAME>

Deploy the app

  1. Ensure you're in your functions project folder.

  2. Deploy the app.

    func azure functionapp publish <APP_NAME>

Known issues

  • Optimizations are not all in place in the consumption plan and you may experience longer cold starts.


Please create issues in this repo. Thanks!


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