[Instrumentation.Http] Set http cancellation error description and type (#1955)

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

Author: jdt

src/OpenTelemetry.Instrumentation.Http/CHANGELOG.md

@@ -9,6 +9,10 @@ Released 2024-Jun-17
 * Updated OpenTelemetry core component version(s) to `1.9.0`.
   ([#1888](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/1888))
 
+* Fix an issue where cancellation of an HTTP request via the Cancellation Token
+  would not set a description or an `error.type` on the activity
+  ([#1831](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/1831))
+
 ## 1.8.1
 
 Released 2024-Apr-12

src/OpenTelemetry.Instrumentation.Http/Implementation/HttpHandlerDiagnosticListener.cs

@@ -183,7 +183,11 @@ public void OnStopActivity(Activity activity, object? payload)
                 {
                     if (currentStatusCode == ActivityStatusCode.Unset)
                     {
-                        activity.SetStatus(ActivityStatusCode.Error);
+                        // Task cancellation won't trigger the OnException so set the span error information here
+                        // This can be either TaskCanceled or OperationCanceled but there is no way to figure out which one it is,
+                        // so let's use the most common case as error type
+                        activity.SetStatus(ActivityStatusCode.Error, "Task Canceled");
+                        activity.SetTag(SemanticConventions.AttributeErrorType, typeof(TaskCanceledException).FullName);
                     }
                 }
                 else if (requestTaskStatus != TaskStatus.Faulted)

test/OpenTelemetry.Instrumentation.Http.Tests/HttpClientTests.Basic.cs

@@ -60,6 +60,12 @@ public HttpClientTests(ITestOutputHelper output)
                 {
                     ctx.Response.StatusCode = int.Parse(responseCode);
                 }
+                else if (ctx.Request.Url != null && ctx.Request.Url.PathAndQuery.Contains("slow"))
+                {
+                    Thread.Sleep(10000);
+                    ctx.Response.RedirectLocation = "/";
+                    ctx.Response.StatusCode = 200;
+                }
                 else
                 {
                     ctx.Response.StatusCode = 200;

test/OpenTelemetry.Instrumentation.Http.Tests/HttpClientTests.cs

@@ -172,6 +172,48 @@ public async Task ValidateNet8MetricsAsync(HttpOutTestCase tc)
     }
 #endif
 
+#if NET8_0_OR_GREATER
+    [Fact]
+    public async Task HttpCancellationLogsError()
+    {
+        var activities = new List<Activity>();
+
+        var tracerProvider = Sdk.CreateTracerProviderBuilder()
+            .AddHttpClientInstrumentation()
+            .AddInMemoryExporter(activities)
+            .Build();
+
+        try
+        {
+            using var c = new HttpClient();
+            using var request = new HttpRequestMessage
+            {
+                RequestUri = new Uri($"{this.url}/slow"),
+                Method = new HttpMethod("GET"),
+            };
+
+            var cancellationTokenSource = new CancellationTokenSource(100);
+            await c.SendAsync(request, cancellationTokenSource.Token);
+        }
+        catch (OperationCanceledException)
+        {
+            // we expect this to be thrown here
+        }
+        finally
+        {
+            tracerProvider.Dispose();
+        }
+
+        var activity = Assert.Single(activities);
+
+        Assert.Equal(ActivityStatusCode.Error, activity.Status);
+        Assert.Equal("Task Canceled", activity.StatusDescription);
+
+        var normalizedAttributes = activity.TagObjects.Where(kv => !kv.Key.StartsWith("otel.", StringComparison.Ordinal)).ToDictionary(x => x.Key, x => x.Value?.ToString());
+        Assert.Contains(normalizedAttributes, kvp => kvp.Key == SemanticConventions.AttributeErrorType && kvp.Value?.ToString() == "System.Threading.Tasks.TaskCanceledException");
+    }
+#endif
+
     private static async Task HttpOutCallsAreCollectedSuccessfullyBodyAsync(
         string host,
         int port,