Add support for .NET8.0 HttpClient metrics

src/OpenTelemetry.Instrumentation.Http/CHANGELOG.md

@@ -34,6 +34,23 @@
   `http.client.request.duration` metrics on .NET Framework for `HttpWebRequest`.
   ([#4870](https://github.com/open-telemetry/opentelemetry-dotnet/pull/4870))
 
+* Following `HttpClient` metrics will now be enabled by default when targeting
+  `.NET8.0` framework.
+
+  * **Meter** : `System.Net.Http`
+    * `http.client.request.duration`
+    * `http.client.active_requests`
+    * `http.client.open_connections`
+    * `http.client.connection.duration`
+    * `http.client.request.time_in_queue`
+
+  * **Meter** : `System.Net.NameResolution`
+    * `dns.lookup.duration`
+
+  **NOTE**: Users can opt-out of metrics that are not required using
+  [views](https://github.com/open-telemetry/opentelemetry-dotnet/tree/main/docs/metrics/customizing-the-sdk#view).
+  [#4931](https://github.com/open-telemetry/opentelemetry-dotnet/pull/4931)
+
 ## 1.5.1-beta.1
 
 Released 2023-Jul-20

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

@@ -31,6 +31,7 @@ namespace OpenTelemetry.Instrumentation.Http.Implementation;
 internal sealed class HttpHandlerMetricsDiagnosticListener : ListenerHandler
 {
     internal const string OnStopEvent = "System.Net.Http.HttpRequestOut.Stop";
+    internal static readonly bool IsNet8OrGreater;
 
     internal static readonly AssemblyName AssemblyName = typeof(HttpClientMetrics).Assembly.GetName();
     internal static readonly string MeterName = AssemblyName.Name;
@@ -45,6 +46,18 @@ internal sealed class HttpHandlerMetricsDiagnosticListener : ListenerHandler
     private readonly bool emitOldAttributes;
     private readonly bool emitNewAttributes;
 
+    static HttpHandlerMetricsDiagnosticListener()
+    {
+        try
+        {
+            IsNet8OrGreater = typeof(HttpClient).Assembly.GetName().Version.Major >= 8;
+        }
+        catch (Exception)
+        {
+            IsNet8OrGreater = false;
+        }
+    }
+
     public HttpHandlerMetricsDiagnosticListener(string name, HttpClientMetricInstrumentationOptions options)
         : base(name)
     {

src/OpenTelemetry.Instrumentation.Http/MeterProviderBuilderExtensions.cs

@@ -64,10 +64,18 @@ public static MeterProviderBuilder AddHttpClientInstrumentation(
             });
         }
 #else
-        builder.AddMeter(HttpHandlerMetricsDiagnosticListener.MeterName);
+        if (HttpHandlerMetricsDiagnosticListener.IsNet8OrGreater)
+        {
+            builder.AddMeter("System.Net.Http");
+            builder.AddMeter("System.Net.NameResolution");
+        }
+        else
+        {
+            builder.AddMeter(HttpHandlerMetricsDiagnosticListener.MeterName);
 
-        builder.AddInstrumentation(sp => new HttpClientMetrics(
-            sp.GetRequiredService<IOptionsMonitor<HttpClientMetricInstrumentationOptions>>().Get(Options.DefaultName)));
+            builder.AddInstrumentation(sp => new HttpClientMetrics(
+                sp.GetRequiredService<IOptionsMonitor<HttpClientMetricInstrumentationOptions>>().Get(Options.DefaultName)));
+        }
 #endif
         return builder;
     }