Add destination to span details

src/Aspire.Dashboard/Components/Controls/SpanDetails.razor.cs

@@ -189,6 +189,15 @@ protected override void OnParametersSet()
                 },
             };
 
+            if (_viewModel.Span.GetDestination() is { } destination)
+            {
+                _valueComponents[KnownTraceFields.DestinationField] = new ComponentMetadata
+                {
+                    Type = typeof(ResourceNameButtonValue),
+                    Parameters = { ["Resource"] = destination }
+                };
+            }
+
             UpdateSpanActionsMenu();
         }
     }

src/Aspire.Dashboard/Components/Pages/TraceDetail.razor.cs

@@ -284,7 +284,7 @@ private void UpdateDetailViewData()
         var result = TelemetryRepository.GetLogs(logsContext);
 
         Logger.LogInformation("Trace '{TraceId}' has {SpanCount} spans.", _trace.TraceId, _trace.Spans.Count);
-        _spanWaterfallViewModels = SpanWaterfallViewModel.Create(_trace, result.Items, new SpanWaterfallViewModel.TraceDetailState(OutgoingPeerResolvers.ToArray(), _collapsedSpanIds));
+        _spanWaterfallViewModels = SpanWaterfallViewModel.Create(_trace, result.Items, new SpanWaterfallViewModel.TraceDetailState(OutgoingPeerResolvers.ToArray(), _collapsedSpanIds, _resources));
         _maxDepth = _spanWaterfallViewModels.Max(s => s.Depth);
 
         var apps = new HashSet<OtlpResource>();

src/Aspire.Dashboard/Extensions/CollectionExtensions.cs

@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
 namespace Aspire.Dashboard.Extensions;
@@ -14,4 +14,25 @@ public static bool Equivalent<T>(this T[] array, T[] other)
 
         return !array.Where((t, i) => !Equals(t, other[i])).Any();
     }
+
+    public static T? SingleOrNull<T>(this IEnumerable<T> source)
+    {
+        ArgumentNullException.ThrowIfNull(source);
+
+        using var enumerator = source.GetEnumerator();
+
+        if (!enumerator.MoveNext())
+        {
+            return default; // no items
+        }
+
+        var first = enumerator.Current;
+
+        if (enumerator.MoveNext())
+        {
+            return default; // more than one
+        }
+
+        return first; // exactly one
+    }
 }

src/Aspire.Dashboard/Model/Otlp/KnownTraceFields.cs

@@ -14,6 +14,7 @@ public static class KnownTraceFields
     // Not used in search.
     public const string StatusMessageField = "trace.statusmessage";
     public const string ParentIdField = "trace.parentid";
+    public const string DestinationField = "trace.destination";
 
     public static readonly List<string> AllFields = [
         NameField,

src/Aspire.Dashboard/Model/Otlp/SpanWaterfallViewModel.cs

@@ -118,7 +118,7 @@ private void UpdateHidden(bool isParentCollapsed = false)
 
     private readonly record struct SpanWaterfallViewModelState(SpanWaterfallViewModel? Parent, int Depth, bool Hidden);
 
-    public sealed record TraceDetailState(IOutgoingPeerResolver[] OutgoingPeerResolvers, List<string> CollapsedSpanIds);
+    public sealed record TraceDetailState(IOutgoingPeerResolver[] OutgoingPeerResolvers, List<string> CollapsedSpanIds, List<OtlpResource> AllResources);
 
     public static string GetTitle(OtlpSpan span, List<OtlpResource> allResources)
     {
@@ -160,7 +160,7 @@ static SpanWaterfallViewModel CreateViewModel(OtlpSpan span, int depth, bool hid
             // A span may indicate a call to another service but the service isn't instrumented.
             var hasPeerService = OtlpHelpers.GetPeerAddress(span.Attributes) != null;
             var isUninstrumentedPeer = hasPeerService && span.Kind is OtlpSpanKind.Client or OtlpSpanKind.Producer && !span.GetChildSpans().Any();
-            var uninstrumentedPeer = isUninstrumentedPeer ? ResolveUninstrumentedPeerName(span, state.OutgoingPeerResolvers) : null;
+            var uninstrumentedPeer = isUninstrumentedPeer ? ResolveUninstrumentedPeerName(span, state.OutgoingPeerResolvers, state.AllResources) : null;
 
             var spanLogVms = new List<SpanLogEntryViewModel>();
             if (spanLogs != null)
@@ -213,12 +213,12 @@ static double CalculatePercent(double value, double total)
         }
     }
 
-    private static string? ResolveUninstrumentedPeerName(OtlpSpan span, IOutgoingPeerResolver[] outgoingPeerResolvers)
+    private static string? ResolveUninstrumentedPeerName(OtlpSpan span, IOutgoingPeerResolver[] outgoingPeerResolvers, List<OtlpResource> allResources)
     {
-        if (span.UninstrumentedPeer?.ResourceName is { } peerName)
+        if (span.UninstrumentedPeer != null)
         {
             // If the span has a peer name, use it.
-            return peerName;
+            return OtlpResource.GetResourceName(span.UninstrumentedPeer, allResources);
         }
 
         // Attempt to resolve uninstrumented peer to a friendly name from the span.

src/Aspire.Dashboard/Model/SpanDetailsViewModel.cs

@@ -25,9 +25,17 @@ public static SpanDetailsViewModel Create(OtlpSpan span, TelemetryRepository tel
         ArgumentNullException.ThrowIfNull(telemetryRepository);
         ArgumentNullException.ThrowIfNull(resources);
 
-        var entryProperties = span.AllProperties()
-                        .Select(f => new TelemetryPropertyViewModel { Name = f.DisplayName, Key = f.Key, Value = f.Value })
-                        .ToList();
+        var entryProperties = span.GetKnownProperties().Select(CreateTelemetryProperty).ToList();
+        if (span.GetDestination() is { } destination)
+        {
+            entryProperties.Add(new TelemetryPropertyViewModel
+            {
+                Name = "Destination",
+                Key = KnownTraceFields.DestinationField,
+                Value = OtlpResource.GetResourceName(destination, resources)
+            });
+        }
+        entryProperties.AddRange(span.GetAttributeProperties().Select(CreateTelemetryProperty));
 
         var traceCache = new Dictionary<string, OtlpTrace>(StringComparer.Ordinal);
 
@@ -44,6 +52,11 @@ public static SpanDetailsViewModel Create(OtlpSpan span, TelemetryRepository tel
             Backlinks = backlinks,
         };
         return spanDetailsViewModel;
+
+        static TelemetryPropertyViewModel CreateTelemetryProperty(OtlpDisplayField f)
+        {
+            return new TelemetryPropertyViewModel { Name = f.DisplayName, Key = f.Key, Value = f.Value };
+        }
     }
 
     private static SpanLinkViewModel CreateLinkViewModel(string traceId, string spanId, KeyValuePair<string, string>[] attributes, TelemetryRepository telemetryRepository, Dictionary<string, OtlpTrace> traceCache)

src/Aspire.Dashboard/Otlp/Model/OtlpSpan.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics;
+using Aspire.Dashboard.Extensions;
 using Aspire.Dashboard.Model.Otlp;
 using Grpc.Core;
 
@@ -98,7 +99,7 @@ public static OtlpSpan Clone(OtlpSpan item, OtlpTrace trace)
         };
     }
 
-    public List<OtlpDisplayField> AllProperties()
+    public List<OtlpDisplayField> GetKnownProperties()
     {
         var props = new List<OtlpDisplayField>
         {
@@ -117,6 +118,13 @@ public List<OtlpDisplayField> AllProperties()
             props.Add(new OtlpDisplayField { DisplayName = "StatusMessage", Key = KnownTraceFields.StatusMessageField, Value = StatusMessage });
         }
 
+        return props;
+    }
+
+    public List<OtlpDisplayField> GetAttributeProperties()
+    {
+        var props = new List<OtlpDisplayField>();
+
         foreach (var kv in Attributes.OrderBy(a => a.Key))
         {
             props.Add(new OtlpDisplayField { DisplayName = kv.Key, Key = $"unknown-{kv.Key}", Value = kv.Value });
@@ -125,6 +133,29 @@ public List<OtlpDisplayField> AllProperties()
         return props;
     }
 
+    public OtlpResource? GetDestination()
+    {
+        // Calculate destination. The destination could either be resolved from:
+        // - An uninstrumented peer, or
+        // - From single child span when the child span has a different resources and is a server/consumer.
+        if (UninstrumentedPeer is { } peer)
+        {
+            return peer;
+        }
+        else
+        {
+            if (GetChildSpans().SingleOrNull() is { } childSpan)
+            {
+                if (childSpan.Source.ResourceKey != Source.ResourceKey && childSpan.Kind is OtlpSpanKind.Server or OtlpSpanKind.Consumer)
+                {
+                    return childSpan.Source.Resource;
+                }
+            }
+        }
+
+        return null;
+    }
+
     private string DebuggerToString()
     {
         return $@"SpanId = {SpanId}, StartTime = {StartTime.ToLocalTime():h:mm:ss.fff tt}, ParentSpanId = {ParentSpanId}, Resource = {Source.ResourceKey}, UninstrumentedPeerResource = {UninstrumentedPeer?.ResourceKey}, TraceId = {Trace.TraceId}";

tests/Aspire.Dashboard.Tests/Model/SpanWaterfallViewModelTests.cs

@@ -29,7 +29,7 @@ public void Create_HasChildren_ChildrenPopulated()
         trace.AddSpan(TelemetryTestHelpers.CreateOtlpSpan(app2, trace, scope, spanId: "1-1", parentSpanId: "1", startDate: new DateTime(2001, 1, 1, 1, 1, 3, DateTimeKind.Utc)));
 
         // Act
-        var vm = SpanWaterfallViewModel.Create(trace, [], new SpanWaterfallViewModel.TraceDetailState([], []));
+        var vm = SpanWaterfallViewModel.Create(trace, [], new SpanWaterfallViewModel.TraceDetailState([], [], []));
 
         // Assert
         Assert.Collection(vm,
@@ -60,7 +60,7 @@ public void Create_RootSpanZeroDuration_ZeroPercentage()
         var log = new OtlpLogEntry(TelemetryTestHelpers.CreateLogRecord(traceId: trace.TraceId, spanId: "1"), app1View, scope, context);
 
         // Act
-        var vm = SpanWaterfallViewModel.Create(trace, [log], new SpanWaterfallViewModel.TraceDetailState([], []));
+        var vm = SpanWaterfallViewModel.Create(trace, [log], new SpanWaterfallViewModel.TraceDetailState([], [], []));
 
         // Assert
         Assert.Collection(vm,
@@ -89,7 +89,7 @@ public void Create_OutgoingPeers_BrowserLink()
         trace.AddSpan(TelemetryTestHelpers.CreateOtlpSpan(app2, trace, scope, spanId: "2", parentSpanId: null, startDate: new DateTime(2001, 2, 1, 1, 1, 2, DateTimeKind.Utc), kind: OtlpSpanKind.Client));
 
         // Act
-        var vm = SpanWaterfallViewModel.Create(trace, [], new SpanWaterfallViewModel.TraceDetailState([new BrowserLinkOutgoingPeerResolver()], []));
+        var vm = SpanWaterfallViewModel.Create(trace, [], new SpanWaterfallViewModel.TraceDetailState([new BrowserLinkOutgoingPeerResolver()], [], []));
 
         // Assert
         Assert.Collection(vm,
@@ -142,7 +142,7 @@ public void MatchesFilter_VariousCases_ReturnsExpected(string filter, bool expec
         var vm = SpanWaterfallViewModel.Create(
             trace,
             [],
-            new SpanWaterfallViewModel.TraceDetailState([], [])).First();
+            new SpanWaterfallViewModel.TraceDetailState([], [], [])).First();
 
         // Act
         var result = vm.MatchesFilter(filter, typeFilter: null, a => a.Resource.ResourceName, out _);
@@ -202,7 +202,7 @@ public void MatchesFilter_SpanType_ReturnsExpected(string spanTypeName, string?
         var vm = SpanWaterfallViewModel.Create(
             trace,
             [],
-            new SpanWaterfallViewModel.TraceDetailState([], [])).First();
+            new SpanWaterfallViewModel.TraceDetailState([], [], [])).First();
 
         // Act 1
         var result1 = vm.MatchesFilter(string.Empty, typeFilter: spanType.Id?.Filter, a => a.Resource.ResourceName, out _);
@@ -234,7 +234,7 @@ public void MatchesFilter_ParentSpanIncludedWhenChildMatched()
         trace.AddSpan(parentSpan);
         trace.AddSpan(childSpan);
 
-        var vms = SpanWaterfallViewModel.Create(trace, [], new SpanWaterfallViewModel.TraceDetailState([], []));
+        var vms = SpanWaterfallViewModel.Create(trace, [], new SpanWaterfallViewModel.TraceDetailState([], [], []));
         var parent = vms[0];
         var child = vms[1];
 
@@ -256,7 +256,7 @@ public void MatchesFilter_ChildSpanIncludedWhenParentMatched()
         trace.AddSpan(parentSpan);
         trace.AddSpan(childSpan);
 
-        var vms = SpanWaterfallViewModel.Create(trace, [], new SpanWaterfallViewModel.TraceDetailState([], []));
+        var vms = SpanWaterfallViewModel.Create(trace, [], new SpanWaterfallViewModel.TraceDetailState([], [], []));
         var parent = vms[0];
         var child = vms[1];
 

tests/Aspire.Dashboard.Tests/TelemetryRepositoryTests/OtlpSpanTests.cs

@@ -26,10 +26,11 @@ public void AllProperties()
             statusCode: OtlpSpanStatusCode.Ok, statusMessage: "Status message!", attributes: [new KeyValuePair<string, string>(KnownTraceFields.StatusMessageField, "value")]);
 
         // Act
-        var properties = span.AllProperties();
+        var knownProperties = span.GetKnownProperties();
+        var attributeProperties = span.GetAttributeProperties();
 
         // Assert
-        Assert.Collection(properties,
+        Assert.Collection(knownProperties,
             a =>
             {
                 Assert.Equal("trace.spanid", a.Key);
@@ -54,11 +55,75 @@ public void AllProperties()
             {
                 Assert.Equal("trace.statusmessage", a.Key);
                 Assert.Equal("Status message!", a.Value);
-            },
+            });
+        Assert.Collection(attributeProperties,
             a =>
             {
                 Assert.Equal("unknown-trace.statusmessage", a.Key);
                 Assert.Equal("value", a.Value);
             });
     }
+
+    [Fact]
+    public void GetDestination_NoChildOrPeer_Null()
+    {
+        // Arrange
+        var context = new OtlpContext { Logger = NullLogger.Instance, Options = new() };
+        var app1 = new OtlpResource("app1", "instance", uninstrumentedPeer: false, context);
+        var trace = new OtlpTrace(new byte[] { 1, 2, 3 }, DateTime.MinValue);
+        var scope = TelemetryTestHelpers.CreateOtlpScope(context);
+
+        var span = TelemetryTestHelpers.CreateOtlpSpan(app1, trace, scope, spanId: "abc", parentSpanId: null, startDate: s_testTime);
+
+        // Act
+        var destination = span.GetDestination();
+
+        // Assert
+        Assert.Null(destination);
+    }
+
+    [Fact]
+    public void GetDestination_HasPeer_ReturnPeerResource()
+    {
+        // Arrange
+        var context = new OtlpContext { Logger = NullLogger.Instance, Options = new() };
+        var app1 = new OtlpResource("app1", "instance", uninstrumentedPeer: false, context);
+        var app2 = new OtlpResource("app2", "instance", uninstrumentedPeer: true, context);
+        var trace = new OtlpTrace(new byte[] { 1, 2, 3 }, DateTime.MinValue);
+        var scope = TelemetryTestHelpers.CreateOtlpScope(context);
+
+        var span = TelemetryTestHelpers.CreateOtlpSpan(app1, trace, scope, spanId: "abc", parentSpanId: null, startDate: s_testTime,
+            kind: OtlpSpanKind.Client, uninstrumentedPeer: app2);
+
+        // Act
+        var destination = span.GetDestination();
+
+        // Assert
+        Assert.Equal(app2, destination);
+    }
+
+    [Fact]
+    public void GetDestination_HasSingleChild_ReturnChildResource()
+    {
+        // Arrange
+        var context = new OtlpContext { Logger = NullLogger.Instance, Options = new() };
+        var app1 = new OtlpResource("app1", "instance", uninstrumentedPeer: false, context);
+        var app2 = new OtlpResource("app2", "instance", uninstrumentedPeer: true, context);
+        var trace = new OtlpTrace(new byte[] { 1, 2, 3 }, DateTime.MinValue);
+        var scope = TelemetryTestHelpers.CreateOtlpScope(context);
+
+        var parentSpan = TelemetryTestHelpers.CreateOtlpSpan(app1, trace, scope, spanId: "abc", parentSpanId: null, startDate: s_testTime,
+            kind: OtlpSpanKind.Client);
+        var childSpan = TelemetryTestHelpers.CreateOtlpSpan(app2, trace, scope, spanId: "abc-2", parentSpanId: "abc", startDate: s_testTime,
+            kind: OtlpSpanKind.Server);
+
+        trace.AddSpan(parentSpan);
+        trace.AddSpan(childSpan);
+
+        // Act
+        var destination = parentSpan.GetDestination();
+
+        // Assert
+        Assert.Equal(app2, destination);
+    }
 }