feat: Add initial plugin for dotnet.

sdk/@launchdarkly/observability-dotnet/AspSampleApp/AspSampleApp.csproj

@@ -7,6 +7,7 @@
     </PropertyGroup>
 
     <ItemGroup>
+        <PackageReference Include="LaunchDarkly.ServerSdk" Version="8.10.0" />
         <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.19"/>
         <PackageReference Include="Swashbuckle.AspNetCore" Version="6.6.2"/>
     </ItemGroup>

sdk/@launchdarkly/observability-dotnet/AspSampleApp/Program.cs

@@ -1,20 +1,24 @@
 using LaunchDarkly.Observability;
+using LaunchDarkly.Sdk;
+using LaunchDarkly.Sdk.Server;
+using LaunchDarkly.Sdk.Server.Integrations;
 
 var builder = WebApplication.CreateBuilder(args);
 
-// Add services to the container.
-// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
 builder.Services.AddEndpointsApiExplorer();
 builder.Services.AddSwaggerGen();
-builder.Services.AddLaunchDarklyObservability(
-    Environment.GetEnvironmentVariable("LAUNCHDARKLY_SDK_KEY"),
-    ldBuilder =>
-    {
-        ldBuilder.WithServiceName("ryan-test-service");
-    }
-);
 
+var config = Configuration.Builder(Environment.GetEnvironmentVariable("LAUNCHDARKLY_SDK_KEY"))
+    .Plugins(new PluginConfigurationBuilder()
+        .Add(ObservabilityPlugin.Builder(builder.Services)
+            .WithServiceName("ryan-test-service")
+            .WithServiceVersion("0.0.0")
+            .Build())).Build();
+
+// Building the LdClient with the Observability plugin. This line will add services to the web application.
+var client = new LdClient(config);
 
+// Client must be built before this line.
 var app = builder.Build();
 
 // Configure the HTTP request pipeline.
@@ -33,11 +37,13 @@
 
 app.MapGet("/weatherforecast", () =>
     {
+        var isMercury =
+            client.BoolVariation("isMercury", Context.New(ContextKind.Of("request"), Guid.NewGuid().ToString()));
         var forecast = Enumerable.Range(1, 5).Select(index =>
                 new WeatherForecast
                 (
                     DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
-                    Random.Shared.Next(-20, 55),
+                    Random.Shared.Next(isMercury ? -170 : -20, isMercury ? 400 : 55),
                     summaries[Random.Shared.Next(summaries.Length)]
                 ))
             .ToArray();

sdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/BaseBuilder.cs

@@ -0,0 +1,116 @@
+using System;
+
+namespace LaunchDarkly.Observability
+{
+    /// <summary>
+    /// Base builder which allows for methods to be shared between building a config directly and building a plugin.
+    /// <remarks>
+    /// This uses the CRTP pattern to allow the individual builder methods to return instances of the derived builder
+    /// type.
+    /// </remarks>
+    /// </summary>
+    public class BaseBuilder<TBuilder> where TBuilder : BaseBuilder<TBuilder>
+    {
+        private const string DefaultOtlpEndpoint = "https://otel.observability.app.launchdarkly.com:4318";
+        private const string DefaultBackendUrl = "https://pub.observability.app.launchdarkly.com";
+        private string _otlpEndpoint = DefaultOtlpEndpoint;
+        private string _backendUrl = DefaultBackendUrl;
+        private string _serviceName = string.Empty;
+        private string _environment = string.Empty;
+        private string _serviceVersion = string.Empty;
+
+        protected BaseBuilder()
+        {
+        }
+
+        /// <summary>
+        /// Set the OTLP endpoint.
+        /// <para>
+        /// For most configurations, the OTLP endpoint will not need to be set.
+        /// </para>
+        /// <para>
+        /// Setting the endpoint to null will reset the builder value to the default.
+        /// </para>
+        /// </summary>
+        /// <param name="otlpEndpoint">The OTLP exporter endpoint URL.</param>
+        /// <returns>A reference to this builder.</returns>
+        public TBuilder WithOtlpEndpoint(string otlpEndpoint)
+        {
+            _otlpEndpoint = otlpEndpoint ?? DefaultOtlpEndpoint;
+            return (TBuilder)this;
+        }
+
+        /// <summary>
+        /// Set the back-end URL for non-telemetry operations.
+        /// <para>
+        /// For most configurations, the backend url will not need to be set.
+        /// </para>
+        /// <para>
+        /// Setting the url to null will reset the builder value to the default.
+        /// </para>
+        /// </summary>
+        /// <param name="backendUrl">The back-end URL used for non-telemetry operations.</param>
+        /// <returns>A reference to this builder.</returns>
+        public TBuilder WithBackendUrl(string backendUrl)
+        {
+            _backendUrl = backendUrl ?? DefaultBackendUrl;
+            return (TBuilder)this;
+        }
+
+        /// <summary>
+        /// Set the service name.
+        /// </summary>
+        /// <param name="serviceName">The logical service name used in telemetry resource attributes.</param>
+        /// <returns>A reference to this builder.</returns>
+        public TBuilder WithServiceName(string serviceName)
+        {
+            _serviceName = serviceName ?? string.Empty;
+            return (TBuilder)this;
+        }
+
+        /// <summary>
+        /// Set the service version.
+        /// </summary>
+        /// <param name="serviceVersion">
+        /// The version of the service that will be added to resource attributes when a service name is provided.
+        /// </param>
+        /// <returns>A reference to this builder.</returns>
+        public TBuilder WithServiceVersion(string serviceVersion)
+        {
+            _serviceVersion = serviceVersion ?? string.Empty;
+            return (TBuilder)this;
+        }
+
+        /// <summary>
+        /// Set the environment name.
+        /// </summary>
+        /// <param name="environment">The environment name (for example, "prod" or "staging").</param>
+        /// <returns>A reference to this builder.</returns>
+        public TBuilder WithEnvironment(string environment)
+        {
+            _environment = environment ?? string.Empty;
+            return (TBuilder)this;
+        }
+
+        /// <summary>
+        /// Build an immutable <see cref="ObservabilityConfig"/> instance.
+        /// </summary>
+        /// <returns>The constructed <see cref="ObservabilityConfig"/>.</returns>
+        internal ObservabilityConfig BuildConfig(string sdkKey)
+        {
+            if (sdkKey == null)
+            {
+                throw new ArgumentNullException(nameof(sdkKey),
+                    "SDK key cannot be null when creating an ObservabilityConfig builder.");
+            }
+
+            return new ObservabilityConfig(
+                _otlpEndpoint,
+                _backendUrl,
+                _serviceName,
+                _environment,
+                _serviceVersion,
+                sdkKey);
+        }
+    }
+}

sdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/LaunchDarkly.Observability.csproj

@@ -54,7 +54,7 @@
   <ItemGroup>
     <!-- LaunchDarkly Dependencies -->
     <PackageReference Include="LaunchDarkly.ServerSdk" Version="[8.10.0,9.0.0)" />
-    <PackageReference Include="LaunchDarkly.ServerSdk.Telemetry" Version="[1.2.0,2.0.0)" />
+    <PackageReference Include="LaunchDarkly.ServerSdk.Telemetry" Version="[1.3.0,2.0.0)" />
   </ItemGroup>
 
   <ItemGroup>

sdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/ObservabilityConfig.cs

@@ -8,14 +8,15 @@ public struct ObservabilityConfig
         /// The configured OTLP endpoint.
         /// </summary>
         public string OtlpEndpoint { get; }
-        
+
         /// <summary>
         /// The configured back-end URL.
         /// <para>
         /// This is used for non-telemetry operations such as accessing the sampling configuration.
         /// </para>
         /// </summary>
         public string BackendUrl { get; }
+
         /// <summary>
         /// The name of the service.
         /// <para>
@@ -24,20 +25,23 @@ public struct ObservabilityConfig
         /// </para>
         /// </summary>
         public string ServiceName { get; }
+
         /// <summary>
         /// The version of the service.
         /// </summary>
         public string ServiceVersion { get; }
+
         /// <summary>
         /// The environment for the service.
         /// </summary>
         public string Environment { get; }
+
         /// <summary>
         /// The LaunchDarkly SDK key.
         /// </summary>
         public string SdkKey { get; }
 
-        private ObservabilityConfig(
+        internal ObservabilityConfig(
             string otlpEndpoint,
             string backendUrl,
             string serviceName,
@@ -56,111 +60,21 @@ private ObservabilityConfig(
         /// <summary>
         /// Create a new builder for <see cref="ObservabilityConfig"/>.
         /// </summary>
-        /// <param name="sdkKey">The LaunchDarkly SDK key used for authentication and resource attributes.</param>
-        /// <returns>A new <see cref="Builder"/> instance for configuring observability.</returns>
-        internal static Builder CreateBuilder(string sdkKey) => new Builder(sdkKey);
+        /// <returns>A new <see cref="ObservabilityConfigBuilder"/> instance for configuring observability.</returns>
+        internal static ObservabilityConfigBuilder Builder() => new ObservabilityConfigBuilder();
 
         /// <summary>
-        /// Fluent builder for <see cref="ObservabilityConfig"/>.
+        /// Builder for building an observability configuration.
         /// </summary>
-        public sealed class Builder
+        public class ObservabilityConfigBuilder : BaseBuilder<ObservabilityConfigBuilder>
         {
-            private const string DefaultOtlpEndpoint = "https://otel.observability.app.launchdarkly.com:4318";
-            private const string DefaultBackendUrl = "https://pub.observability.app.launchdarkly.com";
-            private string _otlpEndpoint = DefaultOtlpEndpoint;
-            private string _backendUrl = DefaultBackendUrl;
-            private string _serviceName = string.Empty;
-            private string _environment = string.Empty;
-            private string _serviceVersion = string.Empty;
-            private readonly string _sdkKey;
-
-            internal Builder(string sdkKey)
-            {
-                _sdkKey = sdkKey ?? throw new ArgumentNullException(nameof(sdkKey), "SDK key cannot be null when creating an ObservabilityConfig builder.");   
-            }
-
-            /// <summary>
-            /// Set the OTLP endpoint.
-            /// <para>
-            /// For most configurations, the OTLP endpoint will not need to be set.
-            /// </para>
-            /// <para>
-            /// Setting the endpoint to null will reset the builder value to the default.
-            /// </para>
-            /// </summary>
-            /// <param name="otlpEndpoint">The OTLP exporter endpoint URL.</param>
-            /// <returns>A reference to this builder.</returns>
-            public Builder WithOtlpEndpoint(string otlpEndpoint)
-            {
-                _otlpEndpoint = otlpEndpoint ?? DefaultOtlpEndpoint;
-                return this;
-            }
-
-            /// <summary>
-            /// Set the back-end URL for non-telemetry operations.
-            /// <para>
-            /// For most configurations, the backend url will not need to be set.
-            /// </para>
-            /// <para>
-            /// Setting the url to null will reset the builder value to the default.
-            /// </para>
-            /// </summary>
-            /// <param name="backendUrl">The back-end URL used for non-telemetry operations.</param>
-            /// <returns>A reference to this builder.</returns>
-            public Builder WithBackendUrl(string backendUrl)
-            {
-                _backendUrl = backendUrl ?? DefaultBackendUrl;
-                return this;
-            }
-
-            /// <summary>
-            /// Set the service name.
-            /// </summary>
-            /// <param name="serviceName">The logical service name used in telemetry resource attributes.</param>
-            /// <returns>A reference to this builder.</returns>
-            public Builder WithServiceName(string serviceName)
-            {
-                _serviceName = serviceName ?? string.Empty;
-                return this;
-            }
-
-            /// <summary>
-            /// Set the service version.
-            /// </summary>
-            /// <param name="serviceVersion">
-            /// The version of the service that will be added to resource attributes when a service name is provided.
-            /// </param>
-            /// <returns>A reference to this builder.</returns>
-            public Builder WithServiceVersion(string serviceVersion)
-            {
-                _serviceVersion =  serviceVersion ?? string.Empty;
-                return this;
-            }
-
-            /// <summary>
-            /// Set the environment name.
-            /// </summary>
-            /// <param name="environment">The environment name (for example, "prod" or "staging").</param>
-            /// <returns>A reference to this builder.</returns>
-            public Builder WithEnvironment(string environment)
+            internal ObservabilityConfigBuilder()
             {
-                _environment = environment ?? string.Empty;
-                return this;
             }
 
-            /// <summary>
-            /// Build an immutable <see cref="ObservabilityConfig"/> instance.
-            /// </summary>
-            /// <returns>The constructed <see cref="ObservabilityConfig"/>.</returns>
-            public ObservabilityConfig Build()
+            internal ObservabilityConfig Build(string sdkKey)
             {
-                return new ObservabilityConfig(
-                    _otlpEndpoint,
-                    _backendUrl,
-                    _serviceName,
-                    _environment,
-                    _serviceVersion,
-                    _sdkKey);
+                return BuildConfig(sdkKey);
             }
         }
     }