[Instrumentation.AspNetCore] metrics - cleanup code after dropping support for .NET6 (#2360)

Author: Kielek

src/OpenTelemetry.Instrumentation.AspNetCore/AspNetCoreInstrumentationMeterProviderBuilderExtensions.cs

@@ -1,10 +1,6 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
-#if !NET
-using OpenTelemetry.Instrumentation.AspNetCore;
-using OpenTelemetry.Instrumentation.AspNetCore.Implementation;
-#endif
 using OpenTelemetry.Internal;
 
 namespace OpenTelemetry.Metrics;
@@ -22,27 +18,15 @@ public static class AspNetCoreInstrumentationMeterProviderBuilderExtensions
     public static MeterProviderBuilder AddAspNetCoreInstrumentation(
         this MeterProviderBuilder builder)
     {
-        Guard.ThrowIfNull(builder);
-
-#if NET
-        return builder.ConfigureMeters();
-#else
-        // Note: Warm-up the status code and method mapping.
-        _ = TelemetryHelper.BoxedStatusCodes;
-        _ = TelemetryHelper.RequestDataHelper;
-
-        builder.AddMeter(HttpInMetricsListener.InstrumentationName);
+#if NETSTANDARD2_0_OR_GREATER
+        if (Environment.Version.Major < 8)
+        {
+            throw new PlatformNotSupportedException("Metrics instrumentation is not supported when executing on .NET 7 and lower.");
+        }
 
-#pragma warning disable CA2000
-        builder.AddInstrumentation(new AspNetCoreMetrics());
-#pragma warning restore CA2000
-
-        return builder;
 #endif
-    }
+        Guard.ThrowIfNull(builder);
 
-    internal static MeterProviderBuilder ConfigureMeters(this MeterProviderBuilder builder)
-    {
         return builder
              .AddMeter("Microsoft.AspNetCore.Hosting")
              .AddMeter("Microsoft.AspNetCore.Server.Kestrel")

src/OpenTelemetry.Instrumentation.AspNetCore/AspNetCoreMetrics.cs

@@ -3,7 +3,8 @@
 ## Unreleased
 
 * Drop support for .NET 6 as this target is no longer supported.
-  ([#2138](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/2138))
+  ([#2138](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/2138),
+  ([#2360](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/2360))
 
 * Updated OpenTelemetry core component version(s) to `1.10.0`.
   ([#2317](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/2317))

src/OpenTelemetry.Instrumentation.AspNetCore/CHANGELOG.md

@@ -113,29 +113,8 @@ public void ConfigureServices(IServiceCollection services)
 }
 ```
 
-Following list of attributes are added by default on
-`http.server.request.duration` metric. See
-[http-metrics](https://github.com/open-telemetry/semantic-conventions/tree/v1.23.0/docs/http/http-metrics.md)
-for more details about each individual attribute. `.NET8.0` and above supports
-additional metrics, see [list of metrics produced](#list-of-metrics-produced) for
-more details.
-
-* `error.type`
-* `http.response.status_code`
-* `http.request.method`
-* `http.route`
-* `network.protocol.version`
-* `url.scheme`
-
 #### List of metrics produced
 
-When the application targets `.NET6.0` or `.NET7.0`, the instrumentation emits
-the following metric:
-
-| Name                              | Details                                                                                                                                                 |
-|-----------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------|
-| `http.server.request.duration`    | [Specification](https://github.com/open-telemetry/semantic-conventions/blob/release/v1.23.x/docs/http/http-metrics.md#metric-httpserverrequestduration) |
-
 Starting from `.NET8.0`, metrics instrumentation is natively implemented, and
 the ASP.NET Core library has incorporated support for [built-in
 metrics](https://learn.microsoft.com/dotnet/core/diagnostics/built-in-metrics-aspnetcore)
@@ -164,16 +143,6 @@ to achieve this.
 > There is no difference in features or emitted metrics when enabling metrics
 using `AddMeter()` or `AddAspNetCoreInstrumentation()` on `.NET8.0` and newer
 versions.
-<!-- This comment is to make sure the two notes above and below are not merged -->
-> [!NOTE]
-> The `http.server.request.duration` metric is emitted in `seconds` as per the
-semantic convention. While the convention [recommends using custom histogram
-buckets](https://github.com/open-telemetry/semantic-conventions/blob/release/v1.23.x/docs/http/http-metrics.md)
-, this feature is not yet available via .NET Metrics API. A
-[workaround](https://github.com/open-telemetry/opentelemetry-dotnet/pull/4820)
-has been included in OTel SDK starting version `1.6.0` which applies recommended
-buckets by default for `http.server.request.duration`. This applies to all
-targeted frameworks.
 
 ## Advanced configuration
 

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

@@ -1,22 +1,13 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
-#if NET
 using System.Threading.RateLimiting;
 using Microsoft.AspNetCore.Builder;
-#endif
 using Microsoft.AspNetCore.Hosting;
-#if NET
 using Microsoft.AspNetCore.Http;
-#endif
 using Microsoft.AspNetCore.Mvc.Testing;
-#if NET
 using Microsoft.AspNetCore.RateLimiting;
-#endif
-#if NET
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.Hosting;
-#endif
 using Microsoft.Extensions.Logging;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.Trace;
@@ -38,7 +29,6 @@ public void AddAspNetCoreInstrumentation_BadArgs()
         Assert.Throws<ArgumentNullException>(builder!.AddAspNetCoreInstrumentation);
     }
 
-#if NET
     [Fact]
     public async Task ValidateNet8MetricsAsync()
     {
@@ -178,7 +168,6 @@ static string GetTicks()
 
         await app.DisposeAsync();
     }
-#endif
 
     [Theory]
     [InlineData("/api/values/2", "api/Values/{id}", null, 200)]