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.NET Aspire Azure Functions integration (Preview)

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Includes: Hosting integration not Client integration

Important

The .NET Aspire Azure Functions integration is currently in preview and is subject to change.

Azure Functions is a serverless solution that allows you to write less code, maintain less infrastructure, and save on costs. The .NET Aspire Azure Functions integration enables you to develop, debug, and orchestrate an Azure Functions .NET project as part of the app host.

It's expected that you've installed the required Azure tooling:

Supported scenarios

The .NET Aspire Azure Functions integration has several key supported scenarios. This section outlines the scenarios and provides details related to the implementation of each approach.

Supported triggers

The following table lists the supported triggers for Azure Functions in the .NET Aspire integration:

Trigger Attribute Details
Azure Event Hubs trigger EventHubTrigger 📦 Aspire.Hosting.Azure.EventHubs
Azure Service Bus trigger ServiceBusTrigger 📦 Aspire.Hosting.Azure.ServiceBus
Azure Storage Blobs trigger BlobTrigger 📦 Aspire.Hosting.Azure.Storage
Azure Storage Queues trigger QueueTrigger 📦 Aspire.Hosting.Azure.Storage
HTTP trigger HttpTrigger Supported without any additional resource dependencies.
Timer trigger TimerTrigger Supported without any additional resource dependencies—relies on implicit host storage.

Important

Other Azure Functions triggers and bindings aren't currently supported in the .NET Aspire Azure Functions integration.

Deployment

Currently, deployment is supported only to containers on Azure Container Apps (ACA) using the SDK container publish function in Microsoft.Azure.Functions.Worker.Sdk. This deployment methodology doesn't currently support KEDA-based autoscaling.

Configure external HTTP endpoints

To make HTTP triggers publicly accessible, call the WithExternalHttpEndpoints API on the AzureFunctionsProjectResource. For more information, see Add Azure Functions resource.

Azure Function project constraints

The .NET Aspire Azure Functions integration has the following project constraints:

If you encounter issues with the Azure Functions project, such as:

There is no Functions runtime available that matches the version specified in the project

In Visual Studio, try checking for an update on the Azure Functions tooling. Open the Options dialog, navigate to Projects and Solutions, and then select Azure Functions. Select the Check for updates button to ensure you have the latest version of the Azure Functions tooling:

Visual Studio: Options / Projects and Solutions / Azure Functions.

Hosting integration

The Azure Functions hosting integration models an Azure Functions resource as the AzureFunctionsProjectResource (subtype of ProjectResource) type. To access this type and APIs that allow you to add it to your app host project install the 📦 Aspire.Hosting.Azure.Functions NuGet package.

dotnet add package Aspire.Hosting.Azure.Functions --prerelease

For more information, see dotnet add package or Manage package dependencies in .NET applications.

Add Azure Functions resource

In your app host project, call AddAzureFunctionsProject on the builder instance to add an Azure Functions resource:

var builder = DistributedApplication.CreateBuilder(args);

var functions = builder.AddAzureFunctionsProject<Projects.ExampleFunctions>("functions")
                       .WithExternalHttpEndpoints();

builder.AddProject<Projects.ExampleProject>()
       .WithReference(functions)
       .WaitFor(functions);

// After adding all resources, run the app...

When .NET Aspire adds an Azure Functions project resource the app host, as shown in the preceding example, the functions resource can be referenced by other project resources. The WithReference method configures a connection in the ExampleProject named "functions". If the Azure Resource was deployed and it exposed an HTTP trigger, its endpoint would be external due to the call to WithExternalHttpEndpoints. For more information, see Reference resources.

Add Azure Functions resource with host storage

If you want to modify the default host storage account that the Azure Functions host uses, call the WithHostStorage method on the Azure Functions project resource:

var builder = DistributedApplication.CreateBuilder(args);

var storage = builder.AddAzureStorage("storage")
                     .RunAsEmulator();

var functions = builder.AddAzureFunctionsProject<Projects.ExampleFunctions>("functions")
                       .WithHostStorage(storage);

builder.AddProject<Projects.ExampleProject>()
       .WithReference(functions)
       .WaitFor(functions);

// After adding all resources, run the app...

The preceding code relies on the 📦 Aspire.Hosting.Azure.Storage NuGet package to add an Azure Storage resource that runs as an emulator. The storage resource is then passed to the WithHostStorage API, explicitly setting the host storage to the emulated resource.

Note

If you're not using the implicit host storage, you must manually assign the StorageAccountContributor role to your resource for deployed instances. This role is automatically assigned for the implicitly generated host storage.

Reference resources in Azure Functions

To reference other Azure resources in an Azure Functions project, chain a call to WithReference on the Azure Functions project resource and provide the resource to reference:

var builder = DistributedApplication.CreateBuilder(args);

var storage = builder.AddAzureStorage("storage").RunAsEmulator();
var blobs = storage.AddBlobs("blobs");

builder.AddAzureFunctionsProject<Projects.ExampleFunctions>("functions")
       .WithHostStorage(storage)
       .WithReference(blobs);

builder.Build().Run();

The preceding code adds an Azure Storage resource to the app host and references it in the Azure Functions project. The blobs resource is added to the storage resource and then referenced by the functions resource. The connection information required to connect to the blobs resource is automatically injected into the Azure Functions project and enables the project to define a BlobTrigger that relies on blobs resource.

See also