.NET (server-side) SDK observability reference

This topic documents how to get started with the LaunchDarkly observability plugin for the .NET (server-side) SDK. The .NET (server-side) SDK supports the observability plugin for error monitoring, logging, and tracing.

SDK quick linksLaunchDarkly’s SDKs are open source. In addition to this reference guide, we provide source, API reference documentation, and a sample application:

Resource	Location
SDK API documentation	Observability plugin API docs
GitHub repository	@launchdarkly/observability-dotnet
Published module	NuGet

Prerequisites and dependencies

This reference guide assumes that you are somewhat familiar with the LaunchDarkly .NET (server-side) SDK. The observability plugin is compatible with the .NET (server-side) SDK, version 8.10 and later. This plugin is designed for use with ASP.Net Core or ASP.Net:

When using .NET or netstandard2.0, the plugin works with ASP.Net Core
When using .NET Framework, the plugin works with ASP.Net

Get started

Follow these steps to get started:

Install the plugin
Initialize the .NET (server-side) SDK client
Configure the plugin options
Explore supported features
Review observability data in LaunchDarkly

Install the plugin

LaunchDarkly uses a plugin to the .NET (server-side) SDK to provide observability. The first step is to make both the SDK and the observability plugin available as dependencies. Here’s how:

  dotnet add package LaunchDarkly.ServerSdk
  dotnet add package LaunchDarkly.Observability

Then, import the LaunchDarkly SDK’s namespaces in your application code. The namespace is not the same as the package name:

using LaunchDarkly.Sdk;
using LaunchDarkly.Sdk.Server;
using LaunchDarkly.Observability;

Initialize the client

Next, initialize the SDK and the plugin. To initialize, you need your LaunchDarkly environment’s SDK key. This authorizes your application to connect to a particular environment within LaunchDarkly. To learn more, read Initialize the client in the .NET (server-side) SDK reference guide. Here’s how to initialize the SDK and plugin:

var builder = WebApplication.CreateBuilder(args);

var config = Configuration.Builder("YOUR_SDK_KEY")
  .StartWaitTime(TimeSpan.FromSeconds(5))
  .Plugins(new PluginConfigurationBuilder()
      .Add(ObservabilityPlugin.Builder(builder.Services)
          .WithServiceName("your-service-name")
          .WithServiceVersion("example-sha")
          .Build()
      )
  ).Build();

var client = new LdClient(config);

// Client must be constructed before the web application.
var app = builder.Build();

// In Global.asax.cs
protected void Application_Start()
{
  // Other application specific code.
  var client = new LdClient(Configuration.Builder("YOUR_SDK_KEY")
      .StartWaitTime(TimeSpan.FromSeconds(5))
      .Plugins(new PluginConfigurationBuilder().Add(ObservabilityPlugin.Builder()
          .WithServiceName("your-service-name")
          .WithServiceVersion("example-sha")
          .Build()))
      .Build());
}

protected void Application_End() {
  Observe.Shutdown();
}

// <!-- 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>

Network requirementsThe observability plugin sends data to LaunchDarkly using port 4318 by default. If your network restricts outbound traffic to port 443, read Network requirements to override the OTLP endpoint.

Configure the plugin options

You can configure options for the observability plugin when you initialize the SDK. The plugin constructor takes an optional object with the configuration details. Here is an example:

var plugin = ObservabilityPlugin.Builder()
  .WithServiceName("example-service")
  .WithServiceVersion("example-sha")
  .Build("YOUR_SDK_KEY");

For more information on plugin options, as well as how they interact with environment variables and existing OpenTelemetry configuration, read Configuration for server-side observability.

Explore supported features

The observability plugin supports the following features. After the SDK and plugins are initialized, you can access these from within your application:

Review observability data in LaunchDarkly

After you initialize the SDK and observability plugin, your application automatically starts sending observability data back to LaunchDarkly in the form of custom events. You can review this information in the LaunchDarkly user interface. To learn how, read Observability and OpenTelemetry autogenerated metrics.

​Prerequisites and dependencies

​Get started

​Install the plugin

​Initialize the client

​Configure the plugin options

​Explore supported features

​Review observability data in LaunchDarkly

Prerequisites and dependencies

Get started

Install the plugin

Initialize the client

Configure the plugin options

Explore supported features

Review observability data in LaunchDarkly