Add OTEL semantic conventions tags to HTTP server activity

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

@@ -11,6 +11,7 @@
 using Microsoft.AspNetCore.Http.Metadata;
 using Microsoft.AspNetCore.Shared;
 using Microsoft.Extensions.Logging;
+using Microsoft.Net.Http.Headers;
 
 namespace Microsoft.AspNetCore.Hosting;
 
@@ -57,10 +58,10 @@ public HostingApplicationDiagnostics(
 
     private static bool GetSuppressActivityOpenTelemetryData()
     {
-        // Default to true if the switch isn't set.
+        // Default to false if the switch isn't set.
         if (!AppContext.TryGetSwitch("Microsoft.AspNetCore.Hosting.SuppressActivityOpenTelemetryData", out var enabled))
         {
-            return true;
+            return false;
         }
 
         return enabled;
@@ -233,7 +234,7 @@ public void RequestEnd(HttpContext httpContext, Exception? exception, HostingApp
         // can capture the activity as a metric exemplar.
         if (activity is not null)
         {
-            StopActivity(httpContext, activity, context.HasDiagnosticListener);
+            StopActivity(httpContext, activity, exception, context.HasDiagnosticListener);
         }
 
         if (context.EventLogEnabled)
@@ -457,6 +458,8 @@ private static TagList CreateInitializeActivityTags(HttpContext httpContext)
         // Missing values recommended by the spec are:
         // - url.query (need configuration around redaction to do properly)
         // - http.request.header.<key>
+        //
+        // Note that these tags are added even if Activity.IsAllDataRequested is false, as they may be used in sampling decisions.
 
         var request = httpContext.Request;
         var creationTags = new TagList();
@@ -473,7 +476,7 @@ private static TagList CreateInitializeActivityTags(HttpContext httpContext)
 
         HostingTelemetryHelpers.SetActivityHttpMethodTags(ref creationTags, request.Method);
 
-        if (request.Headers.TryGetValue("User-Agent", out var values))
+        if (request.Headers.TryGetValue(HeaderNames.UserAgent, out var values))
         {
             var userAgent = values.Count > 0 ? values[0] : null;
             if (!string.IsNullOrEmpty(userAgent))
@@ -491,8 +494,13 @@ private static TagList CreateInitializeActivityTags(HttpContext httpContext)
     }
 
     [MethodImpl(MethodImplOptions.NoInlining)]
-    private void StopActivity(HttpContext httpContext, Activity activity, bool hasDiagnosticListener)
+    private void StopActivity(HttpContext httpContext, Activity activity, Exception? exception, bool hasDiagnosticListener)
     {
+        if (!SuppressActivityOpenTelemetryData && activity.IsAllDataRequested)
+        {
+            SetActivityEndTags(httpContext, activity, exception);
+        }
+
         if (hasDiagnosticListener)
         {
             StopActivity(activity, httpContext);
@@ -503,6 +511,36 @@ private void StopActivity(HttpContext httpContext, Activity activity, bool hasDi
         }
     }
 
+    private static void SetActivityEndTags(HttpContext httpContext, Activity activity, Exception? exception)
+    {
+        var response = httpContext.Response;
+
+        activity.SetTag(HostingTelemetryHelpers.AttributeHttpResponseStatusCode, HostingTelemetryHelpers.GetBoxedStatusCode(response.StatusCode));
+
+        if (HostingTelemetryHelpers.TryGetHttpVersion(httpContext.Request.Protocol, out var httpVersion))
+        {
+            activity.SetTag(HostingTelemetryHelpers.AttributeNetworkProtocolVersion, httpVersion);
+        }
+
+        var endpoint = HttpExtensions.GetOriginalEndpoint(httpContext);
+        var route = endpoint?.Metadata.GetMetadata<IRouteDiagnosticsMetadata>()?.Route;
+        if (route != null)
+        {
+            activity.SetTag(HostingTelemetryHelpers.AttributeHttpRoute, RouteDiagnosticsHelpers.ResolveHttpRoute(route));
+        }
+
+        if (exception != null)
+        {
+            activity.SetTag(HostingTelemetryHelpers.AttributeErrorType, exception.GetType().FullName);
+            activity.SetStatus(ActivityStatusCode.Error, exception.Message);
+        }
+        else if (HostingTelemetryHelpers.IsErrorStatusCode(response.StatusCode))
+        {
+            activity.SetTag(HostingTelemetryHelpers.AttributeErrorType, response.StatusCode.ToString(CultureInfo.InvariantCulture));
+            activity.SetStatus(ActivityStatusCode.Error);
+        }
+    }
+
     // These are versions of DiagnosticSource.Start/StopActivity that don't allocate strings per call (see https://github.com/dotnet/corefx/issues/37055)
     // DynamicDependency matches the properties selected in:
     // https://github.com/dotnet/diagnostics/blob/7cc6fbef613cdfe5ff64393120d59d7a15e98bd6/src/Microsoft.Diagnostics.Monitoring.EventPipe/Configuration/HttpRequestSourceConfiguration.cs#L20-L33

src/Hosting/Hosting/src/Internal/HostingMetrics.cs

@@ -3,6 +3,7 @@
 
 using System.Diagnostics;
 using System.Diagnostics.Metrics;
+using System.Globalization;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Shared;
 
@@ -56,18 +57,18 @@ public void RequestEnd(string protocol, string scheme, string method, string? ro
         {
             if (HostingTelemetryHelpers.TryGetHttpVersion(protocol, out var httpVersion))
             {
-                tags.Add("network.protocol.version", httpVersion);
+                tags.Add(HostingTelemetryHelpers.AttributeNetworkProtocolVersion, httpVersion);
             }
             if (unhandledRequest)
             {
                 tags.Add("aspnetcore.request.is_unhandled", true);
             }
 
             // Add information gathered during request.
-            tags.Add("http.response.status_code", HostingTelemetryHelpers.GetBoxedStatusCode(statusCode));
+            tags.Add(HostingTelemetryHelpers.AttributeHttpResponseStatusCode, HostingTelemetryHelpers.GetBoxedStatusCode(statusCode));
             if (route != null)
             {
-                tags.Add("http.route", RouteDiagnosticsHelpers.ResolveHttpRoute(route));
+                tags.Add(HostingTelemetryHelpers.AttributeHttpRoute, RouteDiagnosticsHelpers.ResolveHttpRoute(route));
             }
 
             // Add before some built in tags so custom tags are prioritized when dealing with duplicates.
@@ -85,7 +86,12 @@ public void RequestEnd(string protocol, string scheme, string method, string? ro
             {
                 // Exception tag could have been added by middleware. If an exception is later thrown in request pipeline
                 // then we don't want to add a duplicate tag here because that breaks some metrics systems.
-                tags.TryAddTag("error.type", exception.GetType().FullName);
+                tags.TryAddTag(HostingTelemetryHelpers.AttributeErrorType, exception.GetType().FullName);
+            }
+            else if (HostingTelemetryHelpers.IsErrorStatusCode(statusCode))
+            {
+                // Add error.type for 5xx status codes when there's no exception.
+                tags.TryAddTag(HostingTelemetryHelpers.AttributeErrorType, statusCode.ToString(CultureInfo.InvariantCulture));
             }
 
             var duration = Stopwatch.GetElapsedTime(startTimestamp, currentTimestamp);
@@ -102,7 +108,7 @@ public void Dispose()
 
     private static void InitializeRequestTags(ref TagList tags, string scheme, string method)
     {
-        tags.Add("url.scheme", scheme);
-        tags.Add("http.request.method", HostingTelemetryHelpers.GetNormalizedHttpMethod(method));
+        tags.Add(HostingTelemetryHelpers.AttributeUrlScheme, scheme);
+        tags.Add(HostingTelemetryHelpers.AttributeHttpRequestMethod, HostingTelemetryHelpers.GetNormalizedHttpMethod(method));
     }
 }

src/Hosting/Hosting/src/Internal/HostingTelemetryHelpers.cs

@@ -11,14 +11,17 @@ namespace Microsoft.AspNetCore.Hosting;
 internal static class HostingTelemetryHelpers
 {
     // Semantic Conventions for HTTP.
-    // Note: Not all telemetry code is using these const attribute names yet.
     public const string AttributeHttpRequestMethod = "http.request.method";
     public const string AttributeHttpRequestMethodOriginal = "http.request.method_original";
+    public const string AttributeHttpResponseStatusCode = "http.response.status_code";
+    public const string AttributeHttpRoute = "http.route";
     public const string AttributeUrlScheme = "url.scheme";
     public const string AttributeUrlPath = "url.path";
     public const string AttributeServerAddress = "server.address";
     public const string AttributeServerPort = "server.port";
     public const string AttributeUserAgentOriginal = "user_agent.original";
+    public const string AttributeNetworkProtocolVersion = "network.protocol.version";
+    public const string AttributeErrorType = "error.type";
 
     // The value "_OTHER" is used for non-standard HTTP methods.
     // https://github.com/open-telemetry/semantic-conventions/blob/v1.23.0/docs/http/http-spans.md#common-attributes
@@ -69,7 +72,7 @@ public static bool TryGetServerPort(HostString host, string scheme, [NotNullWhen
 
     public static object GetBoxedStatusCode(int statusCode)
     {
-        object[] boxes = BoxedStatusCodes;
+        var boxes = BoxedStatusCodes;
         return (uint)statusCode < (uint)boxes.Length
             ? boxes[statusCode] ??= statusCode
             : statusCode;
@@ -129,4 +132,10 @@ public static void SetActivityHttpMethodTags(ref TagList tags, string originalHt
             tags.Add(AttributeHttpRequestMethodOriginal, originalHttpMethod);
         }
     }
+
+    /// <summary>
+    /// Determines if the status code indicates a server error (5xx).
+    /// Client errors (4xx) are not considered server errors.
+    /// </summary>
+    public static bool IsErrorStatusCode(int statusCode) => statusCode >= 500;
 }