OpenFeature 1.5.1

The ID prefix of this package has been reserved for one of the owners of this package by NuGet.org. Prefix Reserved
dotnet add package OpenFeature --version 1.5.1
NuGet\Install-Package OpenFeature -Version 1.5.1
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="OpenFeature" Version="1.5.1" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add OpenFeature --version 1.5.1
#r "nuget: OpenFeature, 1.5.1"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install OpenFeature as a Cake Addin
#addin nuget:?package=OpenFeature&version=1.5.1

// Install OpenFeature as a Cake Tool
#tool nuget:?package=OpenFeature&version=1.5.1

OpenFeature Dark Logo

.NET SDK

Specification Release

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OpenFeature is an open specification that provides a vendor-agnostic, community-driven API for feature flagging that works with your favorite feature flag management tool or in-house solution.

🚀 Quick start

Requirements

  • .NET 6+
  • .NET Core 6+
  • .NET Framework 4.6.2+

Note that the packages will aim to support all current .NET versions. Refer to the currently supported versions .NET and .NET Framework excluding .NET Framework 3.5

Install

Use the following to initialize your project:

dotnet new console

and install OpenFeature:

dotnet add package OpenFeature

Usage

public async Task Example()
{
    // Register your feature flag provider
    await Api.Instance.SetProvider(new InMemoryProvider());

    // Create a new client
    FeatureClient client = Api.Instance.GetClient();

    // Evaluate your feature flag
    bool v2Enabled = await client.GetBooleanValue("v2_enabled", false);

    if ( v2Enabled )
    {
        //Do some work
    }
}

🌟 Features

Status Features Description
✅ Providers Integrate with a commercial, open source, or in-house feature management tool.
✅ Targeting Contextually-aware flag evaluation using evaluation context.
✅ Hooks Add functionality to various stages of the flag evaluation life-cycle.
✅ Logging Integrate with popular logging packages.
✅ Named clients Utilize multiple providers in a single application.
✅ Eventing React to state changes in the provider or flag management system.
✅ Shutdown Gracefully clean up a provider during application shutdown.
✅ Extending Extend OpenFeature with custom providers and hooks.

Implemented: ✅ | In-progress: ⚠️ | Not implemented yet: ❌

Providers

Providers are an abstraction between a flag management system and the OpenFeature SDK. Here is a complete list of available providers.

If the provider you're looking for hasn't been created yet, see the develop a provider section to learn how to build it yourself.

Once you've added a provider as a dependency, it can be registered with OpenFeature like this:

await Api.Instance.SetProvider(new MyProvider());

In some situations, it may be beneficial to register multiple providers in the same application. This is possible using named clients, which is covered in more detail below.

Targeting

Sometimes, the value of a flag must consider some dynamic criteria about the application or user such as the user's location, IP, email address, or the server's location. In OpenFeature, we refer to this as targeting. If the flag management system you're using supports targeting, you can provide the input data using the evaluation context.

// set a value to the global context
EvaluationContextBuilder builder = EvaluationContext.Builder();
builder.Set("region", "us-east-1");
EvaluationContext apiCtx = builder.Build();
Api.Instance.SetContext(apiCtx);

// set a value to the client context
builder = EvaluationContext.Builder();
builder.Set("region", "us-east-1");
EvaluationContext clientCtx = builder.Build();
var client = Api.Instance.GetClient();
client.SetContext(clientCtx);

// set a value to the invocation context
builder = EvaluationContext.Builder();
builder.Set("region", "us-east-1");
EvaluationContext reqCtx = builder.Build();

bool flagValue = await client.GetBooleanValue("some-flag", false, reqCtx);

Hooks

Hooks allow for custom logic to be added at well-defined points of the flag evaluation life-cycle. Look here for a complete list of available hooks. If the hook you're looking for hasn't been created yet, see the develop a hook section to learn how to build it yourself.

Once you've added a hook as a dependency, it can be registered at the global, client, or flag invocation level.

// add a hook globally, to run on all evaluations
Api.Instance.AddHooks(new ExampleGlobalHook());

// add a hook on this client, to run on all evaluations made by this client
var client = Api.Instance.GetClient();
client.AddHooks(new ExampleClientHook());

// add a hook for this evaluation only
var value = await client.GetBooleanValue("boolFlag", false, context, new FlagEvaluationOptions(new ExampleInvocationHook()));

Logging

The .NET SDK uses Microsoft.Extensions.Logging. See the manual for complete documentation.

Named clients

Clients can be given a name. A name is a logical identifier that can be used to associate clients with a particular provider. If a name has no associated provider, the global provider is used.

// registering the default provider
await Api.Instance.SetProvider(new LocalProvider());

// registering a named provider
await Api.Instance.SetProvider("clientForCache", new CachedProvider());

// a client backed by default provider
FeatureClient clientDefault = Api.Instance.GetClient();

// a client backed by CachedProvider
FeatureClient clientNamed = Api.Instance.GetClient("clientForCache");

Eventing

Events allow you to react to state changes in the provider or underlying flag management system, such as flag definition changes, provider readiness, or error conditions. Initialization events (PROVIDER_READY on success, PROVIDER_ERROR on failure) are dispatched for every provider. Some providers support additional events, such as PROVIDER_CONFIGURATION_CHANGED.

Please refer to the documentation of the provider you're using to see what events are supported.

Example usage of an Event handler:

public static void EventHandler(ProviderEventPayload eventDetails)
{
    Console.WriteLine(eventDetails.Type);
}
EventHandlerDelegate callback = EventHandler;
// add an implementation of the EventHandlerDelegate for the PROVIDER_READY event
Api.Instance.AddHandler(ProviderEventTypes.ProviderReady, callback);

It is also possible to register an event handler for a specific client, as in the following example:

EventHandlerDelegate callback = EventHandler;

var myClient = Api.Instance.GetClient("my-client");

var provider = new ExampleProvider();
await Api.Instance.SetProvider(myClient.GetMetadata().Name, provider);

myClient.AddHandler(ProviderEventTypes.ProviderReady, callback);

Shutdown

The OpenFeature API provides a close function to perform a cleanup of all registered providers. This should only be called when your application is in the process of shutting down.

// Shut down all providers
await Api.Instance.Shutdown();

Extending

Develop a provider

To develop a provider, you need to create a new project and include the OpenFeature SDK as a dependency. This can be a new repository or included in the existing contrib repository available under the OpenFeature organization. You’ll then need to write the provider by implementing the FeatureProvider interface exported by the OpenFeature SDK.

public class MyProvider : FeatureProvider
{
    public override Metadata GetMetadata()
    {
        return new Metadata("My Provider");
    }

    public override Task<ResolutionDetails<bool>> ResolveBooleanValue(string flagKey, bool defaultValue, EvaluationContext context = null)
    {
        // resolve a boolean flag value
    }

    public override Task<ResolutionDetails<double>> ResolveDoubleValue(string flagKey, double defaultValue, EvaluationContext context = null)
    {
        // resolve a double flag value
    }

    public override Task<ResolutionDetails<int>> ResolveIntegerValue(string flagKey, int defaultValue, EvaluationContext context = null)
    {
        // resolve an int flag value
    }

    public override Task<ResolutionDetails<string>> ResolveStringValue(string flagKey, string defaultValue, EvaluationContext context = null)
    {
        // resolve a string flag value
    }

    public override Task<ResolutionDetails<Value>> ResolveStructureValue(string flagKey, Value defaultValue, EvaluationContext context = null)
    {
        // resolve an object flag value
    }
}

Develop a hook

To develop a hook, you need to create a new project and include the OpenFeature SDK as a dependency. This can be a new repository or included in the existing contrib repository available under the OpenFeature organization. Implement your own hook by conforming to the Hook interface. To satisfy the interface, all methods (Before/After/Finally/Error) need to be defined.

public class MyHook : Hook
{
  public Task<EvaluationContext> Before<T>(HookContext<T> context,
      IReadOnlyDictionary<string, object> hints = null)
  {
    // code to run before flag evaluation
  }

  public virtual Task After<T>(HookContext<T> context, FlagEvaluationDetails<T> details,
      IReadOnlyDictionary<string, object> hints = null)
  {
    // code to run after successful flag evaluation
  }

  public virtual Task Error<T>(HookContext<T> context, Exception error,
      IReadOnlyDictionary<string, object> hints = null)
  {
    // code to run if there's an error during before hooks or during flag evaluation
  }

  public virtual Task Finally<T>(HookContext<T> context, IReadOnlyDictionary<string, object> hints = null)
  {
    // code to run after all other stages, regardless of success/failure
  }
}

Built a new hook? Let us know so we can add it to the docs!

⭐️ Support the project

🤝 Contributing

Interested in contributing? Great, we'd love your help! To get started, take a look at the CONTRIBUTING guide.

Thanks to everyone who has already contributed

Contrib Rocks

Made with contrib.rocks.

Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 is compatible.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 is compatible.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 is compatible.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 was computed. 
.NET Framework net461 was computed.  net462 is compatible.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
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NuGet packages (16)

Showing the top 5 NuGet packages that depend on OpenFeature:

Package Downloads
DevCycle.SDK.Server.Common

Package Description

CloudBees.OpenFeature.Provider

An OpenFeature provider for CloudBees Feature Management

LaunchDarkly.OpenFeature.ServerProvider

LaunchDarkly OpenFeature Provider for the Server-Side SDK for .NET

OpenFeature.Contrib.Providers.Flagd The ID prefix of this package has been reserved for one of the owners of this package by NuGet.org.

flagd provider for .NET

OpenFeature.Contrib.Hooks.Otel The ID prefix of this package has been reserved for one of the owners of this package by NuGet.org.

Open Telemetry Hook for .NET

GitHub repositories

This package is not used by any popular GitHub repositories.

Version Downloads Last updated
1.5.1 3,460 4/9/2024
1.5.0 3,751 3/12/2024
1.4.1 25,149 1/23/2024
1.4.0 4,500 1/23/2024
1.3.1 273,659 9/19/2023
1.3.0 19,345 7/14/2023
1.2.0 97,381 2/14/2023
1.1.0 2,188 1/18/2023
1.0.1 9,239 10/28/2022
1.0.0 3,380 10/26/2022
0.5.0 5,765 10/16/2022
0.4.0 695 10/12/2022
0.3.0 1,201 9/29/2022
0.2.3 448 9/22/2022
0.1.5 524 9/19/2022
0.1.4 407 9/8/2022
0.1.3 401 8/25/2022
0.1.2 407 8/10/2022
0.1.1 428 7/18/2022
0.1.0 452 7/14/2022