ASPNETCore instrumentation to populate httpflavor tag

src/OpenTelemetry.Instrumentation.AspNetCore/CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+* Tracing instrumentation to populate 'http.flavor' tag.
+  ([3372](https://github.com/open-telemetry/opentelemetry-dotnet/pull/3372))
+
 ## 1.0.0-rc9.4
 
 Released 2022-Jun-03

src/OpenTelemetry.Instrumentation.AspNetCore/Implementation/HttpInListener.cs

@@ -155,6 +155,7 @@ public override void OnStartActivity(Activity activity, object payload)
                 activity.SetTag(SemanticConventions.AttributeHttpMethod, request.Method);
                 activity.SetTag(SemanticConventions.AttributeHttpTarget, path);
                 activity.SetTag(SemanticConventions.AttributeHttpUrl, GetUri(request));
+                activity.SetTag(SemanticConventions.AttributeHttpFlavor, HttpTagHelper.GetFlavorTagValueFromProtocol(request.Protocol));
 
                 var userAgent = request.Headers["User-Agent"].FirstOrDefault();
                 if (!string.IsNullOrEmpty(userAgent))

src/OpenTelemetry.Instrumentation.AspNetCore/Implementation/HttpTagHelper.cs

@@ -0,0 +1,47 @@
+// <copyright file="HttpTagHelper.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Instrumentation.AspNetCore.Implementation
+{
+    /// <summary>
+    /// A collection of helper methods to be used when building Http activities.
+    /// </summary>
+    internal static class HttpTagHelper
+    {
+        /// <summary>
+        /// Gets the OpenTelemetry standard version tag value for a span based on its protocol/>.
+        /// </summary>
+        /// <param name="protocol">.</param>
+        /// <returns>Span flavor value.</returns>
+        public static string GetFlavorTagValueFromProtocol(string protocol)
+        {
+            switch (protocol)
+            {
+                case "HTTP/2":
+                    return "2.0";
+
+                case "HTTP/3":
+                    return "3.0";
+
+                case "HTTP/1.1":
+                    return "1.1";
+
+                default:
+                    return protocol;
+            }
+        }
+    }
+}

test/OpenTelemetry.Instrumentation.AspNetCore.Tests/IncomingRequestsCollectionsIsAccordingToTheSpecTests.cs

@@ -112,6 +112,7 @@ public async Task SuccessfulTemplateControllerCallGeneratesASpan(
             Assert.Equal(ActivityKind.Server, activity.Kind);
             Assert.Equal("localhost", activity.GetTagValue(SemanticConventions.AttributeHttpHost));
             Assert.Equal("GET", activity.GetTagValue(SemanticConventions.AttributeHttpMethod));
+            Assert.Equal("1.1", activity.GetTagValue(SemanticConventions.AttributeHttpFlavor));
             Assert.Equal(urlPath, activity.GetTagValue(SemanticConventions.AttributeHttpTarget));
             Assert.Equal($"http://localhost{urlPath}{query}", activity.GetTagValue(SemanticConventions.AttributeHttpUrl));
             Assert.Equal(statusCode, activity.GetTagValue(SemanticConventions.AttributeHttpStatusCode));