OpenFeature provider for .NET (server-side) SDK

This topic documents how to get started with the LaunchDarkly OpenFeature provider for the .NET (server-side) SDK.

Overview

This topic documents how to get started with the LaunchDarkly OpenFeature provider for the .NET (server-side) SDK.

LaunchDarkly’s OpenFeature providers are open source. In addition to this reference guide, we provide source, API reference documentation, and a sample application:

Resource	Location
OpenFeature Provider API documentation	Provider API docs
GitHub repository	openfeature-dotnet-server
Sample application	Sample OpenFeature .NET provider application
Published module	NuGet

Get started

The LaunchDarkly OpenFeature provider for the .NET (server-side) SDK is intended for use in multi-user systems such as web servers and application. It is not intended for use in desktop and embedded systems applications.

Follow these instructions to start using the LaunchDarkly OpenFeature provider for the .NET (server-side) SDK in your application.

Version compatibility

The LaunchDarkly OpenFeature provider for the .NET (server-side) SDK is compatible with the OpenFeature .NET SDK v2.0.

The provider is compatible with .NET 6.0+, .NET Framework 4.7.1+, and .NET Standard 2.0+.

Install the provider

First, add the LaunchDarkly and OpenFeature packages:

Shell

    dotnet add package LaunchDarkly.ServerSdk
    dotnet add package LaunchDarkly.OpenFeature.ServerProvider
    dotnet add package OpenFeature

Next, import the OpenFeature and LaunchDarkly namespaces in your application code:

LaunchDarkly .NET (server-side) provider

    using LaunchDarkly.OpenFeature.ServerProvider;
    using LaunchDarkly.Sdk.Server;

Initialize the provider

After you install and import the provider, create a single, shared instance of Provider. Specify your SDK key here to authorize your application to connect to a particular environment within LaunchDarkly.

Here’s how:

C#

    var config = Configuration.Builder("YOUR_SDK_KEY")
        .StartWaitTime(TimeSpan.FromSeconds(10))
        .Build();

    var provider = new Provider(config);

    await OpenFeature.Api.Instance.SetProviderAsync(provider);

    var client = OpenFeature.Api.Instance.GetClient();

The configuration options are from the LaunchDarkly .NET (server-side) SDK. To learn more about the configuration options available, read Configuration.

The LaunchDarkly .NET (server-side) provider uses an SDK key. Keys are specific to each project and environment. They are available from Project settings, on the Environments list. To learn more about key types, read Keys.

Construct a context

A context is a generalized way of referring to the people, services, machines, or other resources that encounter feature flags in your product. The OpenFeature specification calls these evaluation contexts.

In the LaunchDarkly provider, contexts:

• always have a particular context kind. If you do not specify a kind, the provider treats the context as having a “user” kind. To specify a different kind, including a multi-context, you must include a kind attribute.
• must have a targeting key. This is optional in the OpenFeature specification, but LaunchDarkly requires a key for evaluation. You can specify this using targetingKey, as in the OpenFeature specification, or key, which is the typical LaunchDarkly identifier for the targeting key.

Here are examples of a context:

Example user context

    var context = EvaluationContext.Builder()
      .Set("targetingKey", "example-user-key") // Could also use "key" instead of "targetingKey".
      .Build();

For additional examples, read OpenFeature specific considerations in the provider GitHub repository.

Evaluate a context

To evaluate feature flags for a context, use the OpenFeature Evaluation API. For example:

Evaluate a context

    var flagValue = await client.GetBooleanValue("example-flag-key", false, context);

Access the Launch

Darkly client

You may need access to the LdClient from within the LaunchDarkly .NET (server-side) SDK if you are working on use cases not supported by OpenFeature, such as migration flags or sending custom events.

To access the LdClient, use GetClient():

C#

    var ldClient = provider.GetClient()