Weird behaviour on starting up Aspire app

[adamtrip]

Sometimes on starting an Aspire app via VS 2022, it immediately launches the browser saying "No resources found" and throws an error.

Error: Grpc.Core.RpcException: Status(StatusCode="Unavailable", Detail="Error connecting to subchannel.", DebugException="System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it.")
 ---> System.Net.Sockets.SocketException (10061): No connection could be made because the target machine actively refused it.
   at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken)
   at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)
   at System.Net.Sockets.Socket.<ConnectAsync>g__WaitForConnectWithCancellation|285_0(AwaitableSocketAsyncEventArgs saea, ValueTask connectTask, CancellationToken cancellationToken)
   at Grpc.Net.Client.Balancer.Internal.SocketConnectivitySubchannelTransport.TryConnectAsync(ConnectContext context)
   --- End of inner exception stack trace ---
   at Grpc.Net.Client.Balancer.Internal.ConnectionManager.PickAsync(PickContext context, Boolean waitForReady, CancellationToken cancellationToken)
   at Grpc.Net.Client.Balancer.Internal.BalancerHttpHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Net.Http.HttpMessageInvoker.<SendAsync>g__SendAsyncWithTelemetry|6_0(HttpMessageHandler handler, HttpRequestMessage request, CancellationToken cancellationToken)
   at Grpc.Net.Client.Internal.GrpcCall`2.RunCall(HttpRequestMessage request, Nullable`1 timeout)
   at Grpc.Net.Client.Internal.Retry.RetryCallBase`2.GetResponseCoreAsync()
   at Aspire.Dashboard.Model.DashboardClient.<>c__DisplayClass23_0.<<EnsureInitialized>g__ConnectAsync|2>d.MoveNext() in /_/src/Aspire.Dashboard/Model/DashboardClient.cs:line 158
--- End of stack trace from previous location ---
   at Aspire.Dashboard.Components.ApplicationName.OnInitializedAsync() in /_/src/Aspire.Dashboard/Components/Controls/ApplicationName.razor.cs:line 32
   at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)

Sometimes it fixes itself, with a VS restart, and other times I have to reboot my PC to make it work again.
This did happen on preview versions 3, 4 and 5 so no specific version bound to this (I think)

[davidfowl]

The dashboard can't connect to the resource server (the app host) for some reason. Is it consistent? I'm going to close this and link the issue here

[davidfowl]

A few questions:

1. When it happens were you launching in VS or outside?
2. Did you use F5 or CTRL+F5 if in VS?
3. The next time it happens, can you look at the environment variables on both the dashboard process and the app host?

[adamtrip]

Is it consistent?

Yes, happens every hour or two.

1. When it happens were you launching in VS or outside?

In VS

2. Did you use F5 or CTRL+F5 if in VS?

Just F5

3. The next time it happens, can you look at the environment variables on both the dashboard process and the app host?

How can I do that?

[davidfowl]

Yes, happens every hour or two.

This is good news, we might be able to pin it down.

How can I do that?

https://learn.microsoft.com/en-us/sysinternals/downloads/process-explorer

I'm guessing that something gets into a bad state wrt the ports chosen causing some errors.

Can you also turn the logging verbosity up on the AppHost project once it starts happening? (in appsettings.json)

[adamtrip]

As soon as I encounter that issue again, I'll debug it with that tool.

I'm guessing that something gets into a bad state wrt the ports chosen causing some errors.

I believe that that might be the case because changing the localhost port on launchsettings doesn't work, the dashboard does not launch, at least on preview 3, on preview 5 haven't tested

[adamtrip]

I believe that that might be the case because changing the localhost port on launchsettings doesn't work, the dashboard does not launch, at least on preview 3, on preview 5 haven't tested

Adding ASPNETCORE_URLS env var fixes the dashboard port change not loading. I was only changing the applicationUrl env var.
Maybe also add ASPNETCORE_URLS variable to the default launchSettings similar to DOTNET_DASHBOARD_OTLP_ENDPOINT_URL

As soon as I encounter that issue again, I'll debug it with that tool.

Today didn't happen yet, still waiting for it to debug it and provide extra info.

[joaojvf]

@adamtrip can you give more explanation about how to fix it? Don't update any port of my application, but I've the same error.

https://github.com/joaojvf/AspirePoc/blob/add-aspire/src/AspirePoc.UI.Api/appsettings.json

[adamtrip]

@joaojvf I've updated to 8.0.0-preview.5.24155.1 and I have not encountered this issue since

[joaojvf]

@adamtrip do you update the .NET Aspire for this version? Because the last one that I found is the 8.0.0-preview.3.24105.21.

[adamtrip]

@joaojvf you can use the daily builds: https://github.com/dotnet/aspire/blob/main/docs/using-latest-daily.md

[davidfowl]

The rule about using daily builds is that you are following the commits to understand the changes. We're in rapid fire mode to beware of breakage 😄

[joaojvf]

Thank you guys! I tried re-implement the Aspire in my project, and worked! I use this project to create a medium post for my company initiative. If you like to see the code and post are here:
post: https://medium.com/@jferreira.ti/implementing-net-aspire-preview-3-24-988235098554
code: https://github.com/joaojvf/AspirePoc

[adamtrip]

@davidfowl since I reported it, it never happened but it happened today. here's the env vars

AppHost

Dashboard

[davidfowl]

The dashboard is connecting to 55072 and it’s failing. Unfortunately I think we need to add logs to narrow this down. It’s possible the app hosts’ resource server failed to start or there’s some caching bug that we have reporting the wrong url

[adamtrip]

out of curiosity I did a net stat and with the app stopped I saw this

[Aspire.Dashboard.exe]
  TCP    127.0.0.1:16051        adam-pc:0              LISTENING
 [Aspire.Dashboard.exe]
  TCP    127.0.0.1:45654        adam-pc:0              LISTENING

[davidfowl]

Take a look at the TCP/IP section on the apphost process.

[adamtrip]

[davidfowl]

The apphost should be listening as well.

[adamtrip]

Found this port missmatch on the logs

info: Aspire.Hosting.Dcp.DcpHostService[0]
      Starting DCP with arguments: start-apiserver --monitor 56024 --detach --kubeconfig "C:\Users\Adam\AppData\Local\Temp\aspire.vmi0wofx.g0i\kubeconfig"
(...)
info: Aspire.Hosting.Dcp.api-server[0]
      API server started        {"Address": "::1", "Port": 58196}

[davidfowl]

Different port. that's the orchestrator not aspire.hosting (even though logs come through that console)