Azure Functions Hosting integration

Deployment

Deployment to Azure Container Apps (ACA) is supported using the SDK container publish function in `Microsoft.Azure.Functions.Worker.Sdk`. When deploying to Azure Container Apps, KEDA-based auto-scaling rules will automatically be configured for your functions.

For more information about the Azure Functions integration with Aspire, see Azure Functions and Aspire integration.

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 Aspire Azure Functions integration has the following project constraints:

• You must target .NET 8.0 or later.
• You must use a .NET 9 SDK or later.
• It currently only supports .NET workers with the isolated worker model.
• Requires the following NuGet packages:
  • 📦 Microsoft.Azure.Functions.Worker: Use the `FunctionsApplicationBuilder`.
  • 📦 Microsoft.Azure.Functions.Worker.Sdk: Adds support for `aspire run` and `aspire deploy`.
  • 📦 Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore: Adds HTTP trigger-supporting APIs.

The Aspire Azure Functions hosting integration models Azure Functions projects as the `AzureFunctionsProjectResource` type. To access this type and APIs for expressing them within your AppHost project, install the 📦 Aspire.Hosting.Azure.Functions NuGet package:

dotnet add package Aspire.Hosting.Azure.Functions

Add Azure Functions resource

In your AppHost project, call AddAzureFunctionsProject on the builder instance to add an Azure Functions resource. There are two ways to add an Azure Functions project, depending on whether the Functions project is referenced in your AppHost project.

Add a referenced Functions project

If the Azure Functions project is referenced in your AppHost project, use the generic overload of AddAzureFunctionsProject:

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...

Add a Functions project by file path

If the Azure Functions project is not referenced in your AppHost project, you can add it by specifying the path to the project file:

var builder = DistributedApplication.CreateBuilder(args);
  
var functions = builder.AddAzureFunctionsProject("functions", "../MyFunctions/MyFunctions.csproj")
    .WithExternalHttpEndpoints();
  
builder.AddProject<Projects.ExampleProject>()
    .WithReference(functions)
    .WaitFor(functions);
  
// After adding all resources, run the app...

In the preceding example, the path to the Functions project file is relative to the AppHost project directory. If the path is not absolute, it will be resolved relative to the AppHost directory.

When Aspire adds an Azure Functions project resource to the AppHost, as shown in the preceding examples, 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.

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.

var builder = DistributedApplication.CreateBuilder(args);
  
var storage = builder.AddAzureStorage("storage");
  
builder.AddAzureFunctionsProject<Projects.ExampleFunctions>("functions")
       .WithHostStorage(storage)
       .WithRoleAssignments(storage, StorageBuiltInRole.StorageBlobDataReader,
                                    StorageBuiltInRole.StorageQueueDataReader);

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 AppHost 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.