[Instrumentation.AspNetCore] Listen to SignalR server activities (open-telemetry#2539)

Co-authored-by: Piotr Kiełkowicz <[email protected]>
Co-authored-by: Rajkumar Rangaraj <[email protected]>

Author: 3 people

build/Common.props

@@ -34,6 +34,7 @@
       Refer to https://docs.microsoft.com/en-us/nuget/concepts/package-versioning for semver syntax.
     -->
     <MinVerPkgVer>[6.0.0,7.0)</MinVerPkgVer>
+    <MicrosoftAspNetCoreSignalRClientPkgVer>[9.0.0,)</MicrosoftAspNetCoreSignalRClientPkgVer>
     <MicrosoftExtensionsHostingAbstractionsPkgVer>[2.1.0,5.0)</MicrosoftExtensionsHostingAbstractionsPkgVer>
     <MicrosoftExtensionsConfigurationPkgVer>[9.0.0,)</MicrosoftExtensionsConfigurationPkgVer>
     <MicrosoftExtensionsOptionsPkgVer>[9.0.0,)</MicrosoftExtensionsOptionsPkgVer>

src/OpenTelemetry.Instrumentation.AspNetCore/.publicApi/PublicAPI.Unshipped.txt

@@ -0,0 +1,2 @@
+OpenTelemetry.Instrumentation.AspNetCore.AspNetCoreTraceInstrumentationOptions.EnableAspNetCoreSignalRSupport.get -> bool
+OpenTelemetry.Instrumentation.AspNetCore.AspNetCoreTraceInstrumentationOptions.EnableAspNetCoreSignalRSupport.set -> void

src/OpenTelemetry.Instrumentation.AspNetCore/AspNetCoreInstrumentationTracerProviderBuilderExtensions.cs

@@ -68,7 +68,7 @@ public static TracerProviderBuilder AddAspNetCoreInstrumentation(
         {
             deferredTracerProviderBuilder.Configure((sp, builder) =>
             {
-                AddAspNetCoreInstrumentationSources(builder, sp);
+                AddAspNetCoreInstrumentationSources(builder, name, sp);
             });
         }
 
@@ -84,9 +84,12 @@ public static TracerProviderBuilder AddAspNetCoreInstrumentation(
     // Note: This is used by unit tests.
     internal static TracerProviderBuilder AddAspNetCoreInstrumentation(
         this TracerProviderBuilder builder,
-        HttpInListener listener)
+        HttpInListener listener,
+        string? optionsName = null)
     {
-        builder.AddAspNetCoreInstrumentationSources();
+        optionsName ??= Options.DefaultName;
+
+        builder.AddAspNetCoreInstrumentationSources(optionsName);
 
 #pragma warning disable CA2000
         return builder.AddInstrumentation(
@@ -96,6 +99,7 @@ internal static TracerProviderBuilder AddAspNetCoreInstrumentation(
 
     private static void AddAspNetCoreInstrumentationSources(
         this TracerProviderBuilder builder,
+        string optionsName,
         IServiceProvider? serviceProvider = null)
     {
         // For .NET7.0 onwards activity will be created using activitySource.
@@ -121,5 +125,16 @@ private static void AddAspNetCoreInstrumentationSources(
             builder.AddSource(HttpInListener.ActivitySourceName);
             builder.AddLegacySource(HttpInListener.ActivityOperationName); // for the activities created by AspNetCore
         }
+
+        // SignalR activities first added in .NET 9.0
+        if (Environment.Version.Major >= 9)
+        {
+            var options = serviceProvider?.GetRequiredService<IOptionsMonitor<AspNetCoreTraceInstrumentationOptions>>().Get(optionsName);
+            if (options is null || options.EnableAspNetCoreSignalRSupport)
+            {
+                // https://github.com/dotnet/aspnetcore/blob/6ae3ea387b20f6497b82897d613e9b8a6e31d69c/src/SignalR/server/Core/src/Internal/SignalRServerActivitySource.cs#L13C35-L13C70
+                builder.AddSource("Microsoft.AspNetCore.SignalR.Server");
+            }
+        }
     }
 }

src/OpenTelemetry.Instrumentation.AspNetCore/AspNetCoreTraceInstrumentationOptions.cs

@@ -93,6 +93,15 @@ internal AspNetCoreTraceInstrumentationOptions(IConfiguration configuration)
     /// </remarks>
     public bool RecordException { get; set; }
 
+    /// <summary>
+    /// Gets or sets a value indicating whether SignalR activities are recorded.
+    /// </summary>
+    /// <remarks>
+    /// Defaults to true.
+    /// Only applies to .NET 9.0 or greater.
+    /// </remarks>
+    public bool EnableAspNetCoreSignalRSupport { get; set; } = true;
+
     /// <summary>
     /// Gets or sets a value indicating whether RPC attributes are added to an Activity when using Grpc.AspNetCore.
     /// </summary>

src/OpenTelemetry.Instrumentation.AspNetCore/CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## Unreleased
 
+* Added support for listening to ASP.NET Core SignalR activities.
+  Configurable with the
+  `AspNetCoreTraceInstrumentationOptions.EnableAspNetCoreSignalRSupport`
+  option which defaults to `true`. Only applies to .NET 9.0 or greater.
+
 ## 1.11.0
 
 Released 2025-Jan-27

test/OpenTelemetry.Instrumentation.AspNetCore.Tests/BasicTests.cs

@@ -7,6 +7,7 @@
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.AspNetCore.SignalR.Client;
 using Microsoft.AspNetCore.TestHost;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
@@ -1114,6 +1115,104 @@ public async Task ValidateUrlQueryRedaction(string urlQuery, string expectedUrlQ
         Assert.Equal(expectedUrlQuery, activity.GetTagValue(SemanticConventions.AttributeUrlQuery));
     }
 
+#if NET9_0_OR_GREATER
+    [Fact]
+    public async Task SignalRActivitesAreListenedTo()
+    {
+        var exportedItems = new List<Activity>();
+        void ConfigureTestServices(IServiceCollection services)
+        {
+            this.tracerProvider = Sdk.CreateTracerProviderBuilder()
+                .AddAspNetCoreInstrumentation()
+                .AddInMemoryExporter(exportedItems)
+                .Build();
+        }
+
+        // Arrange
+        using (var server = this.factory
+            .WithWebHostBuilder(builder =>
+            {
+                builder.ConfigureTestServices(ConfigureTestServices);
+                builder.ConfigureLogging(loggingBuilder => loggingBuilder.ClearProviders());
+            }))
+        {
+            await using var client = new HubConnectionBuilder()
+                .WithUrl(server.Server.BaseAddress + "testHub", o =>
+                {
+                    o.HttpMessageHandlerFactory = _ => server.Server.CreateHandler();
+                    o.Transports = Microsoft.AspNetCore.Http.Connections.HttpTransportType.LongPolling;
+                }).Build();
+            await client.StartAsync();
+
+            await client.SendAsync("Send", "text");
+
+            await client.StopAsync();
+        }
+
+        WaitForActivityExport(exportedItems, 10);
+
+        var hubActivity = exportedItems
+            .Where(a => a.DisplayName.StartsWith("TestApp.AspNetCore.TestHub", StringComparison.InvariantCulture));
+
+        Assert.Equal(3, hubActivity.Count());
+        Assert.Collection(
+            hubActivity,
+            one =>
+            {
+                Assert.Equal("TestApp.AspNetCore.TestHub/OnConnectedAsync", one.DisplayName);
+            },
+            two =>
+            {
+                Assert.Equal("TestApp.AspNetCore.TestHub/Send", two.DisplayName);
+            },
+            three =>
+            {
+                Assert.Equal("TestApp.AspNetCore.TestHub/OnDisconnectedAsync", three.DisplayName);
+            });
+    }
+
+    [Fact]
+    public async Task SignalRActivitesCanBeDisabled()
+    {
+        var exportedItems = new List<Activity>();
+        void ConfigureTestServices(IServiceCollection services)
+        {
+            this.tracerProvider = Sdk.CreateTracerProviderBuilder()
+                .AddAspNetCoreInstrumentation(o => o.EnableAspNetCoreSignalRSupport = false)
+                .AddInMemoryExporter(exportedItems)
+                .Build();
+        }
+
+        // Arrange
+        using (var server = this.factory
+            .WithWebHostBuilder(builder =>
+            {
+                builder.ConfigureTestServices(ConfigureTestServices);
+                builder.ConfigureLogging(loggingBuilder => loggingBuilder.ClearProviders());
+            }))
+        {
+            await using var client = new HubConnectionBuilder()
+                .WithUrl(server.Server.BaseAddress + "testHub", o =>
+                {
+                    o.HttpMessageHandlerFactory = _ => server.Server.CreateHandler();
+                    o.Transports = Microsoft.AspNetCore.Http.Connections.HttpTransportType.LongPolling;
+                }).Build();
+            await client.StartAsync();
+
+            await client.SendAsync("Send", "text");
+
+            await client.StopAsync();
+        }
+
+        WaitForActivityExport(exportedItems, 8);
+
+        var hubActivity = exportedItems
+            .Where(a => a.DisplayName.StartsWith("TestApp.AspNetCore.TestHub", StringComparison.InvariantCulture));
+
+        Assert.Empty(hubActivity);
+    }
+#endif
+
     public void Dispose()
     {
         this.tracerProvider?.Dispose();
@@ -1124,13 +1223,15 @@ private static void WaitForActivityExport(List<Activity> exportedItems, int coun
         // We need to let End callback execute as it is executed AFTER response was returned.
         // In unit tests environment there may be a lot of parallel unit tests executed, so
         // giving some breezing room for the End callback to complete
-        Assert.True(SpinWait.SpinUntil(
+        Assert.True(
+            SpinWait.SpinUntil(
             () =>
             {
                 Thread.Sleep(10);
                 return exportedItems.Count >= count;
             },
-            TimeSpan.FromSeconds(1)));
+            TimeSpan.FromSeconds(1)),
+            $"Actual: {exportedItems.Count} Expected: {count}");
     }
 
     private static void ValidateAspNetCoreActivity(Activity activityToValidate, string expectedHttpPath)

test/OpenTelemetry.Instrumentation.AspNetCore.Tests/OpenTelemetry.Instrumentation.AspNetCore.Tests.csproj

@@ -18,6 +18,7 @@
   <ItemGroup>
     <PackageReference Include="OpenTelemetry.Exporter.InMemory" Version="$(OpenTelemetryCoreLatestVersion)" />
     <PackageReference Include="OpenTelemetry.Extensions.Hosting" Version="$(OpenTelemetryCoreLatestVersion)" />
+    <PackageReference Include="Microsoft.AspNetCore.SignalR.Client" Version="$(MicrosoftAspNetCoreSignalRClientPkgVer)" />
   </ItemGroup>
 
   <ItemGroup>

test/TestApp.AspNetCore/Program.cs

@@ -20,6 +20,8 @@ public static void Main(string[] args)
 
         builder.Services.AddMvc();
 
+        builder.Services.AddSignalR();
+
         builder.Services.AddSingleton<HttpClient>();
 
         builder.Services.AddSingleton(
@@ -43,6 +45,8 @@ public static void Main(string[] args)
 
         app.MapControllers();
 
+        app.MapHub<TestHub>("/testHub");
+
         app.UseMiddleware<CallbackMiddleware>();
 
         app.UseMiddleware<ActivityMiddleware>();

test/TestApp.AspNetCore/TestHub.cs

@@ -0,0 +1,15 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+using Microsoft.AspNetCore.SignalR;
+
+namespace TestApp.AspNetCore;
+
+public class TestHub : Hub
+{
+    public override Task OnConnectedAsync() => base.OnConnectedAsync();
+
+    public void Send(string message)
+    {
+    }
+}