Add OpenTelemetry Package

NATS.Net.slnx

@@ -64,6 +64,7 @@
     <Project Path="src/NATS.Client.JetStream/NATS.Client.JetStream.csproj" />
     <Project Path="src/NATS.Client.KeyValueStore/NATS.Client.KeyValueStore.csproj" />
     <Project Path="src/NATS.Client.ObjectStore/NATS.Client.ObjectStore.csproj" />
+    <Project Path="src/NATS.Client.OpenTelemetry/NATS.Client.OpenTelemetry.csproj" />
     <Project Path="src/NATS.Client.Serializers.Json/NATS.Client.Serializers.Json.csproj" />
     <Project Path="src/NATS.Client.Services/NATS.Client.Services.csproj" />
     <Project Path="src/NATS.Client.Simplified/NATS.Client.Simplified.csproj" />

src/NATS.Client.Core/NatsTelemetry.cs

@@ -0,0 +1,12 @@
+namespace NATS.Client.Core;
+
+/// <summary>
+/// Telemetry identifiers for NATS .NET. Use these when configuring OpenTelemetry
+/// or any other listener directly. The same name is used for both the
+/// <see cref="System.Diagnostics.ActivitySource"/> and the
+/// <see cref="System.Diagnostics.Metrics.Meter"/>.
+/// </summary>
+public static class NatsTelemetry
+{
+    public const string SourceName = "NATS.Net";
+}

src/NATS.Client.OpenTelemetry/NATS.Client.OpenTelemetry.csproj

@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <!-- NuGet Packaging -->
+        <PackageTags>opentelemetry;tracing;metrics;observability;nats</PackageTags>
+        <Description>OpenTelemetry instrumentation for NATS .NET. Adds the ActivitySource and Meter for the client to a TracerProviderBuilder or MeterProviderBuilder.</Description>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="OpenTelemetry.Api" Version="1.15.3" />
+    </ItemGroup>
+
+    <ItemGroup>
+        <ProjectReference Include="..\NATS.Client.Core\NATS.Client.Core.csproj" />
+    </ItemGroup>
+
+</Project>

src/NATS.Client.OpenTelemetry/NatsInstrumentationExtensions.cs

@@ -0,0 +1,22 @@
+using NATS.Client.Core;
+using OpenTelemetry.Metrics;
+using OpenTelemetry.Trace;
+
+namespace NATS.Client.OpenTelemetry;
+
+public static class NatsInstrumentationExtensions
+{
+    /// <summary>
+    /// Adds the NATS .NET client <see cref="System.Diagnostics.ActivitySource"/> to the tracer provider,
+    /// enabling distributed tracing for publish, subscribe, and request/reply operations.
+    /// </summary>
+    public static TracerProviderBuilder AddNatsClientInstrumentation(this TracerProviderBuilder builder) =>
+        builder.AddSource(NatsTelemetry.SourceName);
+
+    /// <summary>
+    /// Adds the NATS .NET client <see cref="System.Diagnostics.Metrics.Meter"/> to the meter provider,
+    /// enabling messaging metrics (published/consumed counters, operation duration, and more).
+    /// </summary>
+    public static MeterProviderBuilder AddNatsClientInstrumentation(this MeterProviderBuilder builder) =>
+        builder.AddMeter(NatsTelemetry.SourceName);
+}

tests/NATS.Net.OpenTelemetry.Tests/NATS.Net.OpenTelemetry.Tests.csproj

@@ -11,6 +11,7 @@
 
     <ItemGroup>
         <PackageReference Include="FluentAssertions" Version="[7,8)" />
+        <PackageReference Include="OpenTelemetry" Version="1.15.3" />
         <PackageReference Include="ProcessX" Version="1.5.6" />
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
         <PackageReference Include="xunit.v3" Version="1.0.1" />
@@ -34,6 +35,7 @@
 
     <ItemGroup>
         <ProjectReference Include="..\..\src\NATS.Client.JetStream\NATS.Client.JetStream.csproj" />
+        <ProjectReference Include="..\..\src\NATS.Client.OpenTelemetry\NATS.Client.OpenTelemetry.csproj" />
         <ProjectReference Include="..\..\src\NATS.Client.Serializers.Json\NATS.Client.Serializers.Json.csproj" />
         <ProjectReference Include="..\NATS.Client.TestUtilities\NATS.Client.TestUtilities.csproj" />
         <ProjectReference Include="..\..\src\NATS.Client.Core\NATS.Client.Core.csproj" />

tests/NATS.Net.OpenTelemetry.Tests/NatsInstrumentationExtensionsTest.cs

@@ -0,0 +1,35 @@
+using NATS.Client.OpenTelemetry;
+using OpenTelemetry;
+using OpenTelemetry.Metrics;
+using OpenTelemetry.Trace;
+
+namespace NATS.Client.Core.Tests;
+
+public class NatsInstrumentationExtensionsTest
+{
+    [Fact]
+    public void AddNatsClientInstrumentation_builds_tracer_provider()
+    {
+        using var provider = Sdk.CreateTracerProviderBuilder()
+            .AddNatsClientInstrumentation()
+            .Build();
+
+        provider.Should().NotBeNull();
+    }
+
+    [Fact]
+    public void AddNatsClientInstrumentation_builds_meter_provider()
+    {
+        using var provider = Sdk.CreateMeterProviderBuilder()
+            .AddNatsClientInstrumentation()
+            .Build();
+
+        provider.Should().NotBeNull();
+    }
+
+    [Fact]
+    public void SourceName_is_NATS_Net()
+    {
+        NatsTelemetry.SourceName.Should().Be("NATS.Net");
+    }
+}