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Author: JamesNK

src/Hosting/Hosting/src/Internal/HostingApplication.cs

@@ -17,6 +17,13 @@ internal sealed class HostingApplication : IHttpApplication<HostingApplication.C
     private readonly DefaultHttpContextFactory? _defaultHttpContextFactory;
     private readonly HostingApplicationDiagnostics _diagnostics;
 
+    // Internal for testing purposes only
+    internal bool SuppressActivityOpenTelemetryData
+    {
+        get => _diagnostics.SuppressActivityOpenTelemetryData;
+        set => _diagnostics.SuppressActivityOpenTelemetryData = value;
+    }
+
     public HostingApplication(
         RequestDelegate application,
         ILogger logger,

src/Hosting/Hosting/src/Internal/HostingApplicationDiagnostics.cs

@@ -33,7 +33,9 @@ internal sealed class HostingApplicationDiagnostics
     private readonly HostingEventSource _eventSource;
     private readonly HostingMetrics _metrics;
     private readonly ILogger _logger;
-    private readonly bool _suppressActivityOpenTelemetryData;
+
+    // Internal for testing purposes only
+    internal bool SuppressActivityOpenTelemetryData { get; set; }
 
     public HostingApplicationDiagnostics(
         ILogger logger,
@@ -49,7 +51,19 @@ public HostingApplicationDiagnostics(
         _propagator = propagator;
         _eventSource = eventSource;
         _metrics = metrics;
-        _suppressActivityOpenTelemetryData = AppContext.TryGetSwitch("Microsoft.AspNetCore.Hosting.SuppressActivityOpenTelemetryData", out var enabled) && enabled;
+
+        SuppressActivityOpenTelemetryData = GetSuppressActivityOpenTelemetryData();
+    }
+
+    private static bool GetSuppressActivityOpenTelemetryData()
+    {
+        // Default to true if the switch isn't set.
+        if (!AppContext.TryGetSwitch("Microsoft.AspNetCore.Hosting.SuppressActivityOpenTelemetryData", out var enabled))
+        {
+            return true;
+        }
+
+        return enabled;
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -395,7 +409,7 @@ private void RecordRequestStartMetrics(HttpContext httpContext)
 
         hasDiagnosticListener = false;
 
-        var initializeTags = !_suppressActivityOpenTelemetryData
+        var initializeTags = !SuppressActivityOpenTelemetryData
             ? CreateInitializeActivityTags(httpContext)
             : (TagList?)null;
 

src/Hosting/Hosting/test/HostingApplicationDiagnosticsTests.cs

@@ -1054,6 +1054,48 @@ public void ActivityListenersAreCalled()
         hostingApplication.CreateContext(features);
         Assert.Equal("0123456789abcdef", parentSpanId);
 
+        Assert.Empty(tags);
+    }
+
+    [Fact]
+    public void ActivityListeners_DontSuppressActivityTags_TagsAdded()
+    {
+        var testSource = new ActivitySource(Path.GetRandomFileName());
+        var hostingApplication = CreateApplication(out var features, activitySource: testSource, suppressActivityOpenTelemetryData: false);
+        var parentSpanId = "";
+        var tags = new List<KeyValuePair<string, object>>();
+        using var listener = new ActivityListener
+        {
+            ShouldListenTo = activitySource => ReferenceEquals(activitySource, testSource),
+            Sample = (ref ActivityCreationOptions<ActivityContext> _) => ActivitySamplingResult.AllData,
+            ActivityStarted = activity =>
+            {
+                parentSpanId = Activity.Current.ParentSpanId.ToHexString();
+                tags = Activity.Current.TagObjects.OrderBy(t => t.Key).ToList();
+            }
+        };
+
+        ActivitySource.AddActivityListener(listener);
+
+        features.Set<IHttpRequestFeature>(new HttpRequestFeature()
+        {
+            Headers = new HeaderDictionary()
+            {
+                {"traceparent", "00-0123456789abcdef0123456789abcdef-0123456789abcdef-01"},
+                {"tracestate", "TraceState1"},
+                {"baggage", "Key1=value1, Key2=value2"},
+                {"host", "localhost:8080" }
+            },
+            PathBase = "/path_base",
+            Path = "/path",
+            Scheme = "http",
+            Method = "CUSTOM_METHOD",
+            Protocol = "HTTP/1.1"
+        });
+
+        hostingApplication.CreateContext(features);
+        Assert.Equal("0123456789abcdef", parentSpanId);
+
         Assert.Collection(tags,
             kvp => AssertKeyValuePair(kvp, "http.request.method", "_OTHER"),
             kvp => AssertKeyValuePair(kvp, "http.request.method_original", "CUSTOM_METHOD"),
@@ -1078,7 +1120,7 @@ static void AssertKeyValuePair<T>(KeyValuePair<string, T> pair, string key, T va
     public void ActivityListeners_DefaultPorts(string scheme, int? expectedPort)
     {
         var testSource = new ActivitySource(Path.GetRandomFileName());
-        var hostingApplication = CreateApplication(out var features, activitySource: testSource);
+        var hostingApplication = CreateApplication(out var features, activitySource: testSource, suppressActivityOpenTelemetryData: false);
         var tags = new Dictionary<string, object>();
         using var listener = new ActivityListener
         {
@@ -1152,7 +1194,8 @@ private static void AssertProperty<T>(object o, string name)
 
     private static HostingApplication CreateApplication(out FeatureCollection features,
         DiagnosticListener diagnosticListener = null, ActivitySource activitySource = null, ILogger logger = null,
-        Action<DefaultHttpContext> configure = null, HostingEventSource eventSource = null, IMeterFactory meterFactory = null)
+        Action<DefaultHttpContext> configure = null, HostingEventSource eventSource = null, IMeterFactory meterFactory = null,
+        bool? suppressActivityOpenTelemetryData = null)
     {
         var httpContextFactory = new Mock<IHttpContextFactory>();
 
@@ -1174,6 +1217,11 @@ private static HostingApplication CreateApplication(out FeatureCollection featur
             eventSource ?? HostingEventSource.Log,
             new HostingMetrics(meterFactory ?? new TestMeterFactory()));
 
+        if (suppressActivityOpenTelemetryData is { } suppress)
+        {
+            hostingApplication.SuppressActivityOpenTelemetryData = suppress;
+        }
+
         return hostingApplication;
     }