Unhandled exception. System.AggregateException: One or more errors occurred. (Unsupported value type System.Int32) ---> System.NotSupportedException: Unsupported value type System.Int32 at Aspire.Hosting.Azure.AzureResourcePreparer...

[mitchdenny]

Using daily build 13.1.0-preview.1.25609.1. Getting an error when trying to launch apphost via Aspire CLI, the exception is:

❯ aspire run
❌ An error occurred while connecting to the app host. The app host possibly crashed before it 
was available: AppHost process has exited unexpectedly. Use --debug to see more details..
Using launch settings from /home/midenn/Code/scratch/pugginess/apphost.run.json...
Building...
Unhandled exception. System.AggregateException: One or more errors occurred. (Unsupported 
value type System.Int32)
 ---> System.NotSupportedException: Unsupported value type System.Int32
   at Aspire.Hosting.Azure.AzureResourcePreparer.ProcessAzureReferences(HashSet`1 
azureReferences, Object value) in /_/src/Aspire.Hosting.Azure/AzureResourcePreparer.cs:line 
472
   at Aspire.Hosting.Azure.AzureResourcePreparer.GetAzureReferences(IResource resource, 
CancellationToken cancellationToken) in 
/_/src/Aspire.Hosting.Azure/AzureResourcePreparer.cs:line 389
   at 
Aspire.Hosting.Azure.AzureResourcePreparer.BuildRoleAssignmentAnnotations(DistributedApplica
tionModel appModel, List`1 azureResources, CancellationToken cancellationToken) in 
/_/src/Aspire.Hosting.Azure/AzureResourcePreparer.cs:line 141
   at Aspire.Hosting.Azure.AzureResourcePreparer.OnBeforeStartAsync(BeforeStartEvent event, 
CancellationToken cancellationToken) in 
/_/src/Aspire.Hosting.Azure/AzureResourcePreparer.cs:line 38
   at 
Aspire.Hosting.Eventing.DistributedApplicationEventing.<>c__DisplayClass4_0`1.<<Subscribe>b_
_0>d.MoveNext() in /_/src/Aspire.Hosting/Eventing/DistributedApplicationEventing.cs:line 82
--- End of stack trace from previous location ---
   at Aspire.Hosting.Eventing.DistributedApplicationEventing.PublishAsync[[T]](T event, 
EventDispatchBehavior dispatchBehavior, CancellationToken cancellationToken) in 
/_/src/Aspire.Hosting/Eventing/DistributedApplicationEventing.cs:line 69
   at Aspire.Hosting.DistributedApplication.ExecuteBeforeStartHooksAsync(CancellationToken 
cancellationToken) in /_/src/Aspire.Hosting/DistributedApplication.cs:line 490
   at Aspire.Hosting.DistributedApplication.RunAsync(CancellationToken cancellationToken) in
/_/src/Aspire.Hosting/DistributedApplication.cs:line 440
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken 
cancellationToken)
   at System.Threading.Tasks.Task.Wait()
   at Aspire.Hosting.DistributedApplication.Run() in 
/_/src/Aspire.Hosting/DistributedApplication.cs:line 471
   at Program.<Main>$(String[[]] args) in 
/home/midenn/Code/scratch/pugginess/apphost.cs:line 58

This is what the apphost looks like:

#:package Aspire.Hosting.Azure.AppContainers@13.1.0-preview.1.25609.1
#:sdk Aspire.AppHost.Sdk@13.1.0-preview.1.25609.1
#:package Aspire.Hosting.JavaScript@13.1.0-preview.1.25609.1
#:package Aspire.Hosting.Python@13.1.0-preview.1.25609.1
#:package Aspire.Hosting.Redis@13.1.0-preview.1.25609.1
#:package Aspire.Hosting.Azure.Storage@13.1.0-preview.1.25609.1
#:package Aspire.Hosting.Azure.CognitiveServices@13.1.0-preview.1.25609.1
#:package CommunityToolkit.Aspire.Hosting.Ollama@13.0.1-beta.468
#:package CommunityToolkit.Aspire.Hosting.k6@13.0.1-beta.468

var builder = DistributedApplication.CreateBuilder(args);

builder.AddAzureContainerAppEnvironment("env");

var cache = builder.AddRedis("cache");

// Azure Blob Storage (uses Azurite emulator locally)
var storage = builder.AddAzureStorage("storage").RunAsEmulator();
var blobs = storage.AddBlobs("blobs");

// Azure OpenAI for cloud-scale vision (GPT-4o with vision)
var openai = builder.AddAzureOpenAI("openai");
var gpt4o = openai.AddDeployment("gpt-4o", "gpt-4o", "2024-08-06");

// Ollama with language model for positive spin on feedback (still local)
var ollama = builder.AddOllama("ollama")
    .WithDataVolume();

var textModel = ollama.AddModel("llama3.2");

var app = builder.AddUvicornApp("app", "./app", "main:app")
    .WithUv()
    .WithExternalHttpEndpoints()
    .WithReference(cache)
    .WaitFor(cache)
    .WithReference(blobs)
    .WaitFor(blobs)
    .WithReference(openai)
    .WaitFor(openai)
    .WithReference(textModel)
    .WaitFor(textModel)
    .WithHttpHealthCheck("/health");

var frontend = builder.AddViteApp("frontend", "./frontend")
    .WithReference(app)
    .WaitFor(app);

app.PublishWithContainerFiles(frontend, "./static");

// k6 load testing for scalability analysis
// Use low VU count (2) and longer duration (2m) since Ollama llava takes ~20s per image on CPU
var k6 = builder.AddK6("k6")
    .WithBindMount("./loadtest", "/scripts", true)
    .WithScript("/scripts/script.js", virtualUsers: 2, duration: "2m")
    .WithReference(app)
    .WaitFor(app);

builder.Build().Run();

[mitchdenny]

@eerhardt any ideas?

[eerhardt]

The issue is we have a bunch of code that doesn't expect primitive values for Arg values. They are expected to be strings. For example:

aspire/src/Aspire.Hosting.Azure/AzureResourcePreparer.cs

Lines 400 to 413 in bd1dbd8

	private static void ProcessAzureReferences(HashSet<IAzureResource> azureReferences, object? value)
	{
	// Null values can be added by environment variable or command line argument callbacks
	// and should be ignored since they cannot contain Azure resource references.
	// See: https://github.com/dotnet/aspire/discussions/11127
	if (value is null)
	{
	return;
	}
	if (value is string or EndpointReference or ParameterResource or EndpointReferenceExpression or HostUrl)
	{
	return;
	}

aspire/src/Aspire.Hosting.Azure.AppContainers/BaseContainerAppContext.cs

Lines 215 to 220 in bd1dbd8

	private (object, SecretType) ProcessValue(object value, SecretType secretType = SecretType.None, object? parent = null)
	{
	if (value is string s)
	{
	return (s, secretType);
	}

aspire/src/Aspire.Hosting.Azure.AppContainers/BaseContainerAppContext.cs

Lines 142 to 152 in bd1dbd8

	private static BicepValue<string> ResolveValue(object val)
	{
	return val switch
	{
	BicepValue<string> s => s,
	string s => s,
	ProvisioningParameter p => p,
	FormattableString fs => BicepFunction.Interpolate(fs),
	_ => throw new NotSupportedException("Unsupported value type " + val.GetType())
	};
	}

So this K6 integration should turn 2 into a string "2" before stuffing it on the Args.

[mitchdenny]

OK, but should that blow up the entire apphost?

[eerhardt]

OK, but should that blow up the entire apphost?

That's how we find these kinds of bugs.

[eerhardt]

We've had a similar issue in the past where we fixed the place creating the argument to use strings. The core Aspire logic can't know how all the primitive types should be converted to strings. For example - should a bool be False, false, or FALSE? It matters sometimes. How should a TimeSpan or DateTime be serialized to a string?

Unhandled exception: Unsupported value type System.Boolean when referencing Azure Storage resource (dotnet/aspire#10432) was the same issue - which we fixed by fixing the Yarp integration to ensure it uses strings - Ensure all YARP env vars are strings (dotnet/aspire#10434).

We should make a similar fix here and fix K6.

[eerhardt]

Opened CommunityToolkit/Aspire#1055 to fix the K6 integration.