Followup after #2098

src/ReverseProxy/Forwarder/ForwarderMiddleware.cs

@@ -45,14 +45,13 @@ public async Task Invoke(HttpContext context)
         activity?.AddTag("proxy.route_id", route.Config.RouteId);
         activity?.AddTag("proxy.cluster_id", cluster.ClusterId);
 
-
         if (destinations.Count == 0)
         {
             Log.NoAvailableDestinations(_logger, cluster.ClusterId);
             context.Response.StatusCode = StatusCodes.Status503ServiceUnavailable;
             context.Features.Set<IForwarderErrorFeature>(new ForwarderErrorFeature(ForwarderError.NoAvailableDestinations, ex: null));
             activity?.SetStatus(ActivityStatusCode.Error);
-            activity?.AddError("Proxy forwarding failed","No available destinations to route to");
+            activity?.AddError("Proxy forwarding failed", "No available destinations to forward to");
             return;
         }
 

src/ReverseProxy/Health/ActiveHealthCheckMonitor.cs

@@ -110,7 +110,7 @@ private async Task ProbeCluster(ClusterState cluster)
         }
 
         // Creates an Activity to trace the active health checks
-        var activity = Observability.YarpActivitySource.StartActivity("proxy.cluster_health_checks", ActivityKind.Consumer);
+        using var activity = Observability.YarpActivitySource.StartActivity("proxy.cluster_health_checks", ActivityKind.Consumer);
         activity?.AddTag("proxy.cluster_id", cluster.ClusterId);
 
         Log.StartingActiveHealthProbingOnCluster(_logger, cluster.ClusterId);
@@ -157,12 +157,15 @@ private async Task ProbeCluster(ClusterState cluster)
             }
 
             Log.StoppedActiveHealthProbingOnCluster(_logger, cluster.ClusterId);
-            activity?.Stop();
         }
     }
 
     private async Task<DestinationProbingResult> ProbeDestinationAsync(ClusterState cluster, DestinationState destination, TimeSpan timeout)
     {
+        using var probeActivity = Observability.YarpActivitySource.StartActivity("proxy.destination_health_check", ActivityKind.Client);
+        probeActivity?.AddTag("proxy.cluster_id", cluster.ClusterId);
+        probeActivity?.AddTag("proxy.destination_id", destination.DestinationId);
+
         HttpRequestMessage request;
         try
         {
@@ -172,36 +175,30 @@ private async Task<DestinationProbingResult> ProbeDestinationAsync(ClusterState
         {
             Log.ActiveHealthProbeConstructionFailedOnCluster(_logger, destination.DestinationId, cluster.ClusterId, ex);
 
+            probeActivity?.SetStatus(ActivityStatusCode.Error);
+
             return new DestinationProbingResult(destination, null, ex);
         }
 
-        using (var probeActivity = Observability.YarpActivitySource.StartActivity("proxy.destination_health_check", ActivityKind.Client))
+        using var cts = new CancellationTokenSource(timeout);
+
+        try
         {
-            probeActivity?.AddTag("proxy.cluster_id", cluster.ClusterId);
-            probeActivity?.AddTag("proxy.destination_id", destination.DestinationId);
-            var cts = new CancellationTokenSource(timeout);
-            try
-            {
-                Log.SendingHealthProbeToEndpointOfDestination(_logger, request.RequestUri, destination.DestinationId, cluster.ClusterId);
-                var response = await cluster.Model.HttpClient.SendAsync(request, cts.Token);
-                Log.DestinationProbingCompleted(_logger, destination.DestinationId, cluster.ClusterId, (int)response.StatusCode);
+            Log.SendingHealthProbeToEndpointOfDestination(_logger, request.RequestUri, destination.DestinationId, cluster.ClusterId);
+            var response = await cluster.Model.HttpClient.SendAsync(request, cts.Token);
+            Log.DestinationProbingCompleted(_logger, destination.DestinationId, cluster.ClusterId, (int)response.StatusCode);
 
-                probeActivity?.SetStatus(ActivityStatusCode.Ok);
+            probeActivity?.SetStatus(ActivityStatusCode.Ok);
 
-                return new DestinationProbingResult(destination, response, null);
-            }
-            catch (Exception ex)
-            {
-                Log.DestinationProbingFailed(_logger, destination.DestinationId, cluster.ClusterId, ex);
+            return new DestinationProbingResult(destination, response, null);
+        }
+        catch (Exception ex)
+        {
+            Log.DestinationProbingFailed(_logger, destination.DestinationId, cluster.ClusterId, ex);
 
-                probeActivity?.SetStatus(ActivityStatusCode.Error);
+            probeActivity?.SetStatus(ActivityStatusCode.Error);
 
-                return new DestinationProbingResult(destination, null, ex);
-            }
-            finally
-            {
-                cts.Dispose();
-            }
+            return new DestinationProbingResult(destination, null, ex);
         }
     }
 }

src/ReverseProxy/Model/ProxyPipelineInitializerMiddleware.cs

@@ -25,7 +25,7 @@ public ProxyPipelineInitializerMiddleware(RequestDelegate next,
         _next = next ?? throw new ArgumentNullException(nameof(next));
     }
 
-    public async Task Invoke(HttpContext context)
+    public Task Invoke(HttpContext context)
     {
         var endpoint = context.GetEndpoint()
            ?? throw new InvalidOperationException($"Routing Endpoint wasn't set for the current request.");
@@ -39,7 +39,7 @@ public async Task Invoke(HttpContext context)
         {
             Log.NoClusterFound(_logger, route.Config.RouteId);
             context.Response.StatusCode = StatusCodes.Status503ServiceUnavailable;
-            return;
+            return Task.CompletedTask;
         }
 
         var destinationsState = cluster.DestinationsState;
@@ -51,11 +51,26 @@ public async Task Invoke(HttpContext context)
             AvailableDestinations = destinationsState.AvailableDestinations,
         });
 
-        using (var activity = Observability.YarpActivitySource.StartActivity("proxy.forwarder", ActivityKind.Server))
+        var activity = Observability.YarpActivitySource.CreateActivity("proxy.forwarder", ActivityKind.Server);
+
+        return activity is null
+            ? _next(context)
+            : AwaitWithActivity(context, activity);
+    }
+
+    private async Task AwaitWithActivity(HttpContext context, Activity activity)
+    {
+        context.SetYarpActivity(activity);
+
+        activity.Start();
+        try
         {
-            context.SetYarpActivity(activity);
             await _next(context);
         }
+        finally
+        {
+            activity.Dispose();
+        }
     }
 
     private static class Log

src/ReverseProxy/Utilities/Observability.cs

@@ -1,13 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 using System.Diagnostics;
-using System.Runtime.CompilerServices;
 using Microsoft.AspNetCore.Http;
 
 namespace Yarp.ReverseProxy.Utilities;
@@ -23,15 +17,16 @@ internal static class Observability
 
     public static void SetYarpActivity(this HttpContext context, Activity? activity)
     {
-        if (activity != null)
+        if (activity is not null)
         {
             context.Features[typeof(YarpActivity)] = activity;
         }
     }
 
     public static void AddError(this Activity activity, string message, string description)
     {
-        if (activity != null) {
+        if (activity is not null)
+        {
             var tagsCollection = new ActivityTagsCollection
             {
                 { "error", message },

src/TelemetryConsumption/Http/HttpEventListenerService.cs

@@ -58,7 +58,7 @@ protected override void OnEvent(IHttpTelemetryConsumer[] consumers, EventWritten
                 break;
 
             case 3:
-                Debug.Assert(eventData.EventName == "RequestFailed" && payload.Count == 0);
+                Debug.Assert(eventData.EventName == "RequestFailed" /* && payload.Count == 0 */);
                 {
                     foreach (var consumer in consumers)
                     {