Send traces/metrics using OTLP from .net 4.8 apps to the dashboard?

[gentledepp]

Hello!

I am currently trying to start migrating a .net 4.8 MVC app and some windows service to .new core.

There is a quite good doc on hosting the new asp.net core version alongside to the legacy MVC app and migrate endpoints incrementally.

Now, I would like to use Aspire to

• help me run all that stuff (windows service, mvc, mvc core, db, etc.)
• and have one common view on the logs/metrics

Using aspire to launch my console app (aka "windows service") and the Aspnet MVC app does work fine.
However, the dashboard shows no data.

I added the opentelemetry stuff

     private TracerProvider _tracerProvider;
     private MeterProvider _meterProvider;

     protected override void Application_Start(object sender, EventArgs e)
     {
         // set application version at startup
         var version =  typeof(MvcApplication).Assembly.GetCustomAttribute<AssemblyFileVersionAttribute>().Version;

         var useOtlpExporter = !string.IsNullOrWhiteSpace(System.Configuration.ConfigurationManager.AppSettings["OTEL_EXPORTER_OTLP_ENDPOINT"]);
         var tracerBuilder = Sdk.CreateTracerProviderBuilder();

         if (useOtlpExporter)
             tracerBuilder.AddOtlpExporter();

         _tracerProvider = tracerBuilder
             .AddAspNetInstrumentation()
             .AddSource($"web_{Environment.MachineName}")
             .SetResourceBuilder(
                 ResourceBuilder.CreateDefault()
                     .AddService(serviceName: $"web_{Environment.MachineName}", serviceVersion: version))

             .Build();

         var meterBuilder = Sdk.CreateMeterProviderBuilder();
         if (useOtlpExporter)
             meterBuilder.AddOtlpExporter();

         _meterProvider = meterBuilder
             .AddRuntimeInstrumentation()
             .Build();

Note: The console app looks similar but does not have the AspNetInstrumentation()

Now, use the configurationbuilder stuff to get environment variables into my ConfigurationManager.AppSettings so aspire can forward all relevant configuration options to my service/web app (e.g. OTEL_EXPORTER_OTLP_ENDPOINT) and this works as I do get all the variables that are defined.

Unfortunately, I still do not see any logs/traces/metrics in the Aspire Dashboard.

My guess is:

• Aspire Dashboard only supports the GRPC protocol
• but GRPC is not supported by .NET 4.8 Supported client platforms

Am I right?

If so, are there any plans to somehow support .net 4.8 by implementing any of the other protocols (http/protobuf, http/json) in the Aspire Dashboard?

[KalleOlaviNiemitalo]

I have a service in development, running on .NET Framework on Windows 10 and exporting telemetry over OTLP to .NET Aspire dashboard version 8.0.0 on http://localhost:18889 (thus not using TLS). Logs, traces, and metrics all show up on the dashboard. I am not using .NET Aspire orchestration; I start the dashboard from the command line, and the service from the command line or as a Visual Studio project.

Wireshark shows the protocol is some sort of GRPC over HTTP/2 over TCP over IPv6 (::1). HTTP headers include:

content-type: application/grpc
te: trailers
grpc-accept-encoding: identity, deflate, gzip
grpc-timeout: 9910m
user-agent: grpc-csharp/2.44.0 (.NET Framework 4.8.9256.0; CLR 4.0.30319.42000; net45; x64) grpc-c/22.0.0 (windows; chttp2)

This service references the OpenTelemetry.Exporter.OpenTelemetryProtocol 1.8.1 package (not yet upgraded to 1.9.0). On net462, that package depends on "Grpc (>= 2.44.0 && < 3.0.0)" and thus the gRPC C# core-library, which will be deprecated some time after October 2024, rather than the Grpc.Net.Client package. Related: open-telemetry/opentelemetry-dotnet#4613.

Might you have an authentication problem? I haven't bothered to secure the OTLP endpoint, because it's on localhost and used only for development so far.

[KalleOlaviNiemitalo]

I didn't try your repro but I set up something similar. The problem seems to be specific to https. If I run the AppHost project with a launch profile that sets environment variables "DOTNET_DASHBOARD_OTLP_ENDPOINT_URL": "http://localhost:19161" and "ASPIRE_ALLOW_UNSECURED_TRANSPORT": "true", then I get traces and metrics from the .NET Framework ASP.NET MVC application all right.

The aspnetmvc resource name in the following screen shots comes from the builder.AddProject<Projects.WebApplication1>("aspnetmvc") call in the AppHost project. It goes to an environment variable that ResourceBuilder.CreateDefault() picks up.

I hope there is some way to make it work with https in production environments. If not directly, then perhaps via the OpenTelemetry Collector.

OpenTelemetry SDK self-diagnostics seem somewhat usable for logging the exceptions thrown from the OTLP exporter, without breaking to Visual Studio and causing gRPC deadline errors.

The GET {controller}/{action}/{id} span name matches semantic conventions but it'll be pretty useless if every span has that name. It can be overridden by registering these in AspNetTraceInstrumentationOptions:

        private static void EnrichWithHttpRequest(Activity activity, HttpRequest httpRequest)
        {
            // Don't set Activity.DisplayName here, because:
            //
            // * ASP.NET hasn't parsed the route values from the request yet.
            // * OpenTelemetry.Instrumentation.AspNet will overwrite DisplayName
            //   when the request finishes.
            //   <https://github.com/open-telemetry/opentelemetry-dotnet-contrib/issues/1948>
            //
            // Just save the HttpRequest so that EnrichWithHttpResponse can find it.
            activity.SetCustomProperty("HttpRequest", httpRequest);
        }

        private static void EnrichWithHttpResponse(Activity activity, HttpResponse response)
        {
            // Get the HttpRequest that was saved by EnrichWithHttpRequest.
            if (activity.GetCustomProperty("HttpRequest") is HttpRequest httpRequest)
            {
                RouteData routeData = httpRequest.RequestContext.RouteData;
                if (routeData.Route is Route route
                    && route.Url == "{controller}/{action}/{id}"
                    && routeData.Values.TryGetValue("controller", out object controller)
                    && routeData.Values.TryGetValue("action", out object action))
                {
                    // Replace the "GET {controller}/{action}/{id}" or similar
                    // DisplayName with something that shows the controller and action.
                    // Omit any "id" route value though; too high cardinality.
                    activity.DisplayName = $"{httpRequest.HttpMethod} {controller}/{action}/{{id}}";
#if false // not part of OpenTelemetry HTTP semantic conventions
                    activity.AddTag("http.route_data.controller", controller);
                    activity.AddTag("http.route_data.action", action);
#endif
                }
            }
        }

[gentledepp]

can you please provide the full code so I can check?

[KalleOlaviNiemitalo]

AspireApp1.zip

[gentledepp]

Thank you for the sample!
It works now.

Interesting that "HTTPS" seems to be the culprit here. @davidfowl could you be so kind and forward this to somebody that could explain this or help out? (Sorry for bothering you :-|)

[CZEMacLeod]

I have some stuff to help with this in an example I set up at C3D.Extensions.Aspire.IISExpress and there is some discussion in #4984.
As you say - one of the big issues seems to be the otlp/grpc implementation for net framework doesn't seem to support https.