feat: Add support for non-core ASP.Net. (#199)

## Summary

Adds support for ASP.Net on .Net Framework.
netstandard2.0 and dotnet 8.0 support ASP.Net core.

Code that is common between the two is shared, code and dependencies
that are not common are conditionally included.

## How did you test this change?

Manual testing.

## Are there any deployment considerations?

<!--
 Backend - Do we need to consider migrations or backfilling data?
-->

Author: kinyoklion

sdk/@launchdarkly/observability-dotnet/.gitignore

@@ -2,6 +2,8 @@
 **/obj
 LaunchDarkly.Observability.sln.DotSettings.user
 **/launchSettings.json
+**/.vs/**
+packages/
 docs/
 api/
 nupkgs/

sdk/@launchdarkly/observability-dotnet/README.md

@@ -9,7 +9,7 @@ LaunchDarkly Observability Plugin for .Net
 
 **NB: APIs are subject to change until a 1.x version is released.**
 
-## Install
+## Install for ASP.Net Core
 
 ```shell
 dotnet add package LaunchDarkly.Observability
@@ -18,7 +18,54 @@ dotnet add package LaunchDarkly.Observability
 Install the plugin when configuring your LaunchDarkly SDK.
 
 ```csharp
- // TODO: Add example.
+var builder = WebApplication.CreateBuilder(args);
+
+
+var config = Configuration.Builder("your-sdk-key")
+    .Plugins(new PluginConfigurationBuilder()
+        .Add(ObservabilityPlugin.Builder(builder.Services)
+            .WithServiceName("your-service-name")
+            .WithServiceVersion("example-sha")
+            .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();
+```
+
+## Install for an ASP.Net application with .Net Framework 
+
+```csharp
+// In Global.asax.cs
+protected void Application_Start()
+ {
+     // Other application specific code.
+     var client = new LdClient(Configuration.Builder("your-sdk-key")
+         .Plugins(new PluginConfigurationBuilder().Add(ObservabilityPlugin.Builder()
+             .WithServiceName("your-service-name")
+             .WithServiceVersion("example-sha")
+             .Build()))
+         .Build());
+ }
+ 
+ protected void Application_End() {
+     Observe.Shutdown();
+ }
+```
+
+```xml
+<!-- In Web.config -->
+<system.webServer>
+  // Any existing content should remain and the following should be added.
+  <modules>
+  <add name="TelemetryHttpModule" type="OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule,
+    OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule" preCondition="integratedMode,managedHandler" />
+  </modules>
+</system.webServer>
 ```
 
 LaunchDarkly overview
@@ -49,4 +96,4 @@ We encourage pull requests and other contributions from the community. Check out
 [dotnetplugin-sdk-ci]: https://github.com/launchdarkly/observability-sdk/actions/workflows/dotnet-plugin.yml
 [o11y-docs-link]: https://launchdarkly.github.io/observability-sdk/sdk/@launchdarkly/observability-dotnet/
 [dotnetplugin-nuget-badge]: https://img.shields.io/nuget/v/LaunchDarkly.Observability.svg?style=flat-square
-[dotnetplugin-nuget-link]: https://www.nuget.org/packages/LaunchDarkly.Observability/
+[dotnetplugin-nuget-link]: https://www.nuget.org/packages/LaunchDarkly.Observability/

sdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/Asp/Core/ObservabilityExtensions.cs

@@ -0,0 +1,105 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using LaunchDarkly.Observability.Otel;
+using LaunchDarkly.Logging;
+using LaunchDarkly.Observability.Logging;
+using LaunchDarkly.Observability.Sampling;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using OpenTelemetry;
+using OpenTelemetry.Resources;
+using OpenTelemetry.Trace;
+using OpenTelemetry.Exporter;
+using OpenTelemetry.Logs;
+using OpenTelemetry.Metrics;
+
+// ReSharper disable once CheckNamespace
+namespace LaunchDarkly.Observability
+{
+    /// <summary>
+    /// Static class containing extension methods for configuring observability
+    /// </summary>
+    public static class ObservabilityExtensions
+    {
+        private class LdObservabilityHostedService : IHostedService
+        {
+            private readonly ObservabilityConfig _config;
+            private readonly ILoggerProvider _loggerProvider;
+
+            public LdObservabilityHostedService(ObservabilityConfig config, IServiceProvider provider)
+            {
+                _loggerProvider = provider.GetService<ILoggerProvider>();
+                _config = config;
+            }
+
+            public Task StartAsync(CancellationToken cancellationToken)
+            {
+                Observe.Initialize(_config, _loggerProvider);
+                return Task.CompletedTask;
+            }
+
+            public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+        }
+
+        internal static void AddLaunchDarklyObservabilityWithConfig(this IServiceCollection services,
+            ObservabilityConfig config, Logger logger = null)
+        {
+            DebugLogger.SetLogger(logger);
+
+            var sampler = CommonOtelOptions.GetSampler(config);
+
+            var resourceBuilder = CommonOtelOptions.GetResourceBuilder(config);
+
+            services.AddOpenTelemetry().WithTracing(tracing =>
+            {
+                tracing
+                    .WithCommonLaunchDarklyConfig(config, resourceBuilder, sampler)
+                    .AddAspNetCoreInstrumentation(options => { options.RecordException = true; });
+            }).WithLogging(logging =>
+            {
+                logging.SetResourceBuilder(resourceBuilder)
+                    .AddProcessor(new SamplingLogProcessor(sampler))
+                    .AddOtlpExporter(options =>
+                    {
+                        options.WithCommonLaunchDarklyLoggingExport(config);
+                    });
+                config.ExtendedLoggerConfiguration?.Invoke(logging);
+            }).WithMetrics(metrics =>
+            {
+                metrics
+                    .WithCommonLaunchDarklyConfig(config, resourceBuilder)
+                    .AddAspNetCoreInstrumentation();
+            });
+
+            // Attach a hosted service which will allow us to get a logger provider instance from the built
+            // service collection.
+            services.AddHostedService((serviceProvider) =>
+                new LdObservabilityHostedService(config, serviceProvider));
+        }
+
+        /// <summary>
+        /// Add the LaunchDarkly Observability services. This function would typically be called by the LaunchDarkly
+        /// Observability plugin. This should only be called by the end user if the Observability plugin needs to be
+        /// initialized earlier than the LaunchDarkly client.
+        /// </summary>
+        /// <param name="services">The service collection</param>
+        /// <param name="sdkKey">The LaunchDarkly SDK</param>
+        /// <param name="configure">A method to configure the services</param>
+        /// <returns>The service collection</returns>
+        public static IServiceCollection AddLaunchDarklyObservability(
+            this IServiceCollection services,
+            string sdkKey,
+            Action<ObservabilityConfig.ObservabilityConfigBuilder> configure)
+        {
+            var builder = ObservabilityConfig.Builder();
+            configure(builder);
+
+            var config = builder.Build(sdkKey);
+            AddLaunchDarklyObservabilityWithConfig(services, config);
+            return services;
+        }
+    }
+}

…kly.Observability/ObservabilityPlugin.cs …vability/Asp/Core/ObservabilityPlugin.cssdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/ObservabilityPlugin.cs renamed to sdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/Asp/Core/ObservabilityPlugin.cs sdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/ObservabilityPlugin.cs renamed to sdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/Asp/Core/ObservabilityPlugin.cs

@@ -6,7 +6,9 @@
 using LaunchDarkly.Sdk.Server.Plugins;
 using LaunchDarkly.Sdk.Server.Telemetry;
 using Microsoft.Extensions.DependencyInjection;
+using OpenTelemetry.Logs;
 
+// ReSharper disable once CheckNamespace
 namespace LaunchDarkly.Observability
 {
     public class ObservabilityPlugin : Plugin
@@ -20,7 +22,7 @@ public class ObservabilityPlugin : Plugin
         /// In a typical configuration, this method will not need to be used.
         /// </para>
         /// <para>
-        /// This method only needs to be used when observability related functionality must be intialized before it
+        /// This method only needs to be used when observability related functionality must be initialized before it
         /// is possible to initialize the LaunchDarkly SDK.
         /// </para>
         /// </summary>
@@ -32,15 +34,16 @@ public class ObservabilityPlugin : Plugin
         /// <para>
         /// When using this builder, LaunchDarkly client must be constructed before your application is built.
         /// For example:
+        ///
         /// <code>
         /// var builder = WebApplication.CreateBuilder(args);
         ///
         ///
-        /// var config = Configuration.Builder(Environment.GetEnvironmentVariable("your-sdk-key")
+        /// var config = Configuration.Builder("your-sdk-key")
         ///     .Plugins(new PluginConfigurationBuilder()
         ///         .Add(ObservabilityPlugin.Builder(builder.Services)
         ///             .WithServiceName("ryan-test-service")
-        ///             .WithServiceVersion("0.0.0")
+        ///             .WithServiceVersion("example-sha")
         ///             .Build())).Build();
         /// // Building the LdClient with the Observability plugin. This line will add services to the web application.
         /// var client = new LdClient(config);

sdk/@launchdarkly/observability-dotnet/src/LaunchDarkly.Observability/Asp/Legacy/ObservabilityPlugin.cs

@@ -0,0 +1,113 @@
+using System.Collections.Generic;
+using LaunchDarkly.Sdk.Integrations.Plugins;
+using LaunchDarkly.Sdk.Server.Hooks;
+using LaunchDarkly.Sdk.Server.Interfaces;
+using LaunchDarkly.Sdk.Server.Plugins;
+using LaunchDarkly.Sdk.Server.Telemetry;
+
+// ReSharper disable once CheckNamespace
+namespace LaunchDarkly.Observability
+{
+    public class ObservabilityPlugin : Plugin
+    {
+        private readonly ObservabilityPluginBuilder _config;
+
+        /// <summary>
+        /// Create a new builder for <see cref="ObservabilityPlugin"/>.
+        /// <para>
+        /// When using this builder, LaunchDarkly client must be constructed during Application_Start of your
+        /// web application in Global.asax.cs.
+        /// For example:
+        ///
+        /// <code>
+        ///   protected void Application_Start()
+        ///  {
+        ///      // Other application specific code.
+        ///      var client = new LdClient(Configuration.Builder("your-sdk-key")
+        ///          .Plugins(new PluginConfigurationBuilder().Add(ObservabilityPlugin.Builder()
+        ///              .WithServiceName("classic-asp-application")
+        ///              .WithServiceVersion("example-sha")
+        ///              .Build()))
+        ///          .Build());
+        ///  }
+        ///
+        ///  protected void Application_End() {
+        ///      Observe.Shutdown();
+        ///  }
+        /// </code>
+        ///
+        /// Additionally the Web.config must include the following.
+        ///
+        /// <code>
+        ///  <system.webServer>
+        ///    // Any existing content should remain and the following should be added.
+        ///    <modules>
+        ///    <add name="TelemetryHttpModule" type="OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule,
+        ///      OpenTelemetry.Instrumentation.AspNet.TelemetryHttpModule" preCondition="integratedMode,managedHandler" />
+        ///    </modules>
+        ///  </system.webServer>
+        /// </code>
+        /// 
+        /// </para>
+        /// </summary>
+        /// <returns>A new <see cref="ObservabilityPluginBuilder"/> instance for configuring the observability plugin.</returns>
+        public static ObservabilityPluginBuilder Builder() =>
+            new ObservabilityPluginBuilder();
+
+        /// <summary>
+        /// Construct a plugin which is intended to be used with already configured observability services.
+        /// <para>
+        /// In a typical configuration, this method will not need to be used.
+        /// </para>
+        /// <para>
+        /// This method only needs to be used when observability related functionality must be initialized before it
+        /// is possible to initialize the LaunchDarkly SDK.
+        /// </para>
+        /// </summary>
+        /// <returns>an observability plugin instance</returns>
+        public static ObservabilityPlugin ForExistingServices() => new ObservabilityPlugin();
+
+        internal ObservabilityPlugin(ObservabilityPluginBuilder config) : base(
+            "LaunchDarkly.Observability")
+        {
+            _config = config;
+        }
+
+        internal ObservabilityPlugin() : base("LaunchDarkly.Observability")
+        {
+            _config = null;
+        }
+
+        /// <inheritdoc />
+        public override void Register(ILdClient client, EnvironmentMetadata metadata)
+        {
+            if (_config == null) return;
+            var config = _config.BuildConfig(metadata.Credential);
+            OpenTelemetry.Register(config);
+        }
+
+        /// <inheritdoc />
+        public override IList<Hook> GetHooks(EnvironmentMetadata metadata)
+        {
+            return new List<Hook>
+            {
+                TracingHook.Builder().IncludeValue().Build()
+            };
+        }
+
+        /// <summary>
+        /// Used to build an instance of the Observability Plugin.
+        /// </summary>
+        public sealed class ObservabilityPluginBuilder : BaseBuilder<ObservabilityPluginBuilder>
+        {
+            /// <summary>
+            /// Build an <see cref="ObservabilityPlugin"/> instance with the configured settings.
+            /// </summary>
+            /// <returns>The constructed <see cref="ObservabilityPlugin"/>.</returns>
+            public ObservabilityPlugin Build()
+            {
+                return new ObservabilityPlugin(this);
+            }
+        }
+    }
+}