feat(Unleash): add Unleash provider by PSanetra · Pull Request #652 · open-feature/dotnet-sdk-contrib

PSanetra · 2026-05-19T08:59:06Z

This PR

Adds a new OpenFeature provider for Unleash using the Unleash .NET SDK v6 and OpenFeature SDK v2
The provider creates and owns its own DefaultUnleash client instance (no external IUnleash accepted) to properly participate in the OpenFeature initialization lifecycle via Unleash's ReadyEvent/ErrorEvent callbacks
Supports file bootstrap for offline usage (ToggleBootstrapProvider), skipping HTTP initialization when configured
Emits ProviderConfigurationChanged events when Unleash fires TogglesUpdatedEvent
Maps OpenFeature EvaluationContext to Unleash context (TargetingKey → UserId, well-known keys like sessionId, remoteAddress, environment, appName, currentTime, and custom properties)
Boolean evaluation uses IsEnabled; string/int/double/structure use GetVariant with payload parsing
Exposes the Unleash variant payload-type as flag metadata in ResolutionDetails, matching the Java provider pattern

Related Issues

None

Notes

The provider does not accept an external IUnleash instance because the Unleash SDK only allows subscribing to lifecycle events (ReadyEvent, ErrorEvent, TogglesUpdatedEvent) during client construction. Without these events, the provider cannot properly signal readiness or configuration changes to the OpenFeature SDK.
The variant payload Type field (e.g., "string", "number", "json", "csv") is exposed as payload-type flag metadata for consumers to inspect. The provider does not alter parsing behavior based on the type — it always treats the value as a raw string and attempts parsing based on the OpenFeature evaluation method called (matching the Java provider behavior).
Tests use file bootstrap

gemini-code-assist

Code Review

This pull request introduces a new Unleash provider for the OpenFeature .NET SDK, including a context transformer to map evaluation contexts to Unleash contexts and a provider implementation for resolving various flag types. The feedback focuses on aligning the implementation with the PR description by capturing and exposing the Unleash variant payload-type as metadata within the resolution details. This involves updating the internal VariantResolution struct and the evaluation methods to ensure the payload type is correctly propagated.

Signed-off-by: PSanetra <code@psanetra.de>

…d events - Remove external IUnleash constructor; only UnleashSettings is supported since lifecycle events are only available during client construction - Skip waiting for ReadyEvent when ToggleBootstrapProvider is configured (bootstrap loads synchronously) - Emit ProviderConfigurationChanged when Unleash fires TogglesUpdatedEvent - Rewrite tests to use real DefaultUnleash with file bootstrap - Split test classes into separate files Signed-off-by: PSanetra <code@psanetra.de>

…ails Match the Java provider pattern: include the Unleash variant payload type as 'payload-type' in ImmutableMetadata on all variant-based evaluations. Also fix bootstrap.json to use 'number' type for numeric payloads per Unleash conventions. Signed-off-by: PSanetra <code@psanetra.de>

Signed-off-by: PSanetra <code@psanetra.de>

askpt · 2026-05-19T15:25:58Z

@PSanetra Thank you so much for your contribution. Please note the package name should be OpenFeature.Providers.Unleash. Would you mind doing the renaming to fix it?

PSanetra · 2026-05-19T15:32:33Z

@askpt I can do that, but it seems like there is already some inconsistency between the provider package names. E.g. the Flipt provider is called OpenFeature.Contrib.Providers.Flipt and the Flagd provider is called OpenFeature.Providers.Flagd. Is there a reason for the different names?

Unleash/unleash-dotnet-sdk#141 was fixed in Unleash.Client 6.2.1 Signed-off-by: PSanetra <code@psanetra.de>

askpt · 2026-05-19T15:48:04Z

@askpt I can do that, but it seems like there is already some inconsistency between the provider package names. E.g. the Flipt provider is called OpenFeature.Contrib.Providers.Flipt and the Flagd provider is called OpenFeature.Providers.Flagd. Is there a reason for the different names?

@PSanetra We decided to go OpenFeature.Providers.* have a look at this issue: #154 or #195. I am trying to rename a few to follow the latest pattern but it takes time. The new providers should follow the latest guidelines.

…enFeature.Providers.Unleash Signed-off-by: PSanetra <code@psanetra.de>

PSanetra · 2026-05-19T16:09:18Z

@askpt Alright, I have renamed the packages and namespaces 🙂

askpt

Did a quick assessment and it seems a very good quality PR. Thanks for your contribution!

Added some small comments.

askpt · 2026-05-19T17:53:45Z

+        string flagKey, bool defaultValue, EvaluationContext context = null, CancellationToken cancellationToken = default)
+    {
+        var unleashContext = ContextTransformer.Transform(context);
+        var result = this._unleash.IsEnabled(flagKey, unleashContext, defaultValue);


I am not familiar with Unleash but, does it return a Evaluation Details? I am asking because you are assuming all with be static evaluations and in case flag_not_found for example, we should populate the ResolutionDetails correctly.

This applies to all evaluations.

If I have not missed something, I think it is not easily possible to distinguish between disabled and non existing flags. In the non-boolean cases I now return Reason.Disabled if the unleash.GetVariant(...) call returns Variant.DISABLED_VARIANT. But I think this is also returned when the flag does not exist.

I think in theory we could also check if the flag is returned from unleash.ListKnownToggles(). But I am not sure if it really returns a flag if it is disabled.

…ion lifecycle - Rename ContextTransformer to EvaluationContextExtensions with extension method context.ToUnleashContext() - Add GetAppName() extension method for safe appName extraction - Use string.IsNullOrWhiteSpace for TargetingKey check - Enable nullable reference types on both projects - Emit PROVIDER_ERROR event when Unleash fires ErrorEvent - Replace direct IUnleash field with TaskCompletionSource<IUnleash>: InitializeAsync awaits the TCS which resolves eventually once ReadyEvent, ErrorEvent, or cancellation occurs. The client instance is always provided as the result (Unleash SDK handles its own defaults when not yet ready). - Evaluation methods return ProviderNotReady only when InitializeAsync has not been called at all (_clientTcs is null) - ShutdownAsync awaits the client task before disposing - Store initialization EvaluationContext as baseline and merge it with per-call context using EvaluationContextBuilder.Merge (per-call wins) - Apply appName from initialization context to UnleashSettings - Add tests for: EmitProviderError, ProviderNotReady before init, whitespace targeting key, cancellation, error completion, SetReady Signed-off-by: PSanetra <code@psanetra.de>

…d of throwing Replace TypeMismatchException throws with ResolutionDetails containing ErrorType.TypeMismatch and Reason.Error when variant payloads cannot be parsed as the requested numeric type. This returns the default value along with error metadata rather than raising an exception. Signed-off-by: PSanetra <code@psanetra.de>

When GetVariant returns DISABLED_VARIANT (toggle disabled or not found), return ResolutionDetails with Reason.Disabled instead of Reason.Default. This more accurately reflects the Unleash SDK semantics. Signed-off-by: PSanetra <code@psanetra.de>

PSanetra · 2026-05-20T12:47:38Z

@askpt I think your comments can now be resolved, but please have a second look.

OpenFeature SDK already merges the initialization context with per-call context before passing it to the provider, so storing and merging it ourselves is redundant. Signed-off-by: PSanetra <code@psanetra.de>

Signed-off-by: PSanetra <code@psanetra.de>

askpt · 2026-05-22T10:54:09Z

@PSanetra Could you please add yourself as a component owner? https://github.com/open-feature/dotnet-sdk-contrib/blob/main/.github/component_owners.yml

Sorry if I am slowly reviewing this PR. The initialisation and lifecycle are quite complex 😄

PSanetra · 2026-05-22T11:06:42Z

No worries, I have added myself 🙂

Signed-off-by: PSanetra <code@psanetra.de>

kylejuliandev · 2026-05-22T18:49:47Z

+        {
+            var client = await clientTask.ConfigureAwait(false);
+            client?.Dispose();
+        }


suggestion(non-blocking): should the field this._clientTcs be set to null after we have disposed of it? This would prevent subsequent calls to resolve a flag from throwing a Disposed exception, and instead get a ProviderNotReady error

kylejuliandev · 2026-05-22T19:00:55Z

+        await provider.InitializeAsync(EvaluationContext.Empty, cts.Token);
+
+        // Evaluations still work (client was created, just not ready)
+        var result = await provider.ResolveBooleanValueAsync("flag", true);


thought: looking at the method I don't think the CancellationToken is passed to the Unleash task & client, so if a user needed to cancel during flag evaluation this wouldn't be possible?

@kylejuliandev good catch! I have added WaitAsync(cancellationToken) to those places where the client is awaited.

…-dispose Nulling _clientTcs in ShutdownAsync ensures post-shutdown evaluations return ProviderNotReady instead of calling into the disposed client. Signed-off-by: PSanetra <code@psanetra.de>

Use WaitAsync(cancellationToken) so awaiting the client task can be cancelled. Also target net8.0;net10.0 for both src and test projects. Signed-off-by: PSanetra <code@psanetra.de>

…ider

PSanetra requested review from a team as code owners May 19, 2026 08:59

gemini-code-assist Bot reviewed May 19, 2026

View reviewed changes

Comment thread src/OpenFeature.Providers.Unleash/UnleashProvider.cs

Comment thread src/OpenFeature.Providers.Unleash/UnleashProvider.cs

Comment thread src/OpenFeature.Providers.Unleash/UnleashProvider.cs

Comment thread src/OpenFeature.Providers.Unleash/UnleashProvider.cs

PSanetra added 5 commits May 19, 2026 11:21

feat(Unleash): add Unleash provider

514798a

Signed-off-by: PSanetra <code@psanetra.de>

ci: add Unleash provider to release-please configuration

9bca632

Signed-off-by: PSanetra <code@psanetra.de>

docs(Unleash): add version.txt and README.md

b2a625b

Signed-off-by: PSanetra <code@psanetra.de>

PSanetra force-pushed the feat/add-unleash-provider branch from 7665972 to b2a625b Compare May 19, 2026 09:21

test(Unleash): remove workaround

1de0631

Unleash/unleash-dotnet-sdk#141 was fixed in Unleash.Client 6.2.1 Signed-off-by: PSanetra <code@psanetra.de>

PSanetra force-pushed the feat/add-unleash-provider branch from 8f1620d to 1de0631 Compare May 19, 2026 15:36

PSanetra force-pushed the feat/add-unleash-provider branch from a05abb9 to 1de0631 Compare May 19, 2026 16:04

refactor(Unleash): rename OpenFeature.Contrib.Providers.Unleash to Op…

ee1618b

…enFeature.Providers.Unleash Signed-off-by: PSanetra <code@psanetra.de>

github-actions Bot assigned askpt, ericpattison, jenshenneberg, markphelps, matthewelwell, toddbaert and vpetrusevici May 19, 2026

Merge branch 'main' into feat/add-unleash-provider

a9f8674

askpt reviewed May 19, 2026

View reviewed changes

askpt requested review from beeme1mr, kylejuliandev, lukas-reining and toddbaert May 19, 2026 17:59

askpt requested a review from arttonoyan May 19, 2026 18:00

PSanetra added 3 commits May 20, 2026 14:19

PSanetra added 2 commits May 21, 2026 11:38

refactor(Unleash): remove baseline context storage and merge logic

72bbfe7

OpenFeature SDK already merges the initialization context with per-call context before passing it to the provider, so storing and merging it ourselves is redundant. Signed-off-by: PSanetra <code@psanetra.de>

docs(Unleash): add README.md to OpenFeature.Providers.Unleash.csproj

8d3b727

Signed-off-by: PSanetra <code@psanetra.de>

github-actions Bot assigned PSanetra May 22, 2026

chore(Unleash): add psanetra as component owner

a69c1b6

Signed-off-by: PSanetra <code@psanetra.de>

PSanetra force-pushed the feat/add-unleash-provider branch from f716f07 to a69c1b6 Compare May 22, 2026 11:08

kylejuliandev reviewed May 22, 2026

View reviewed changes

PSanetra added 3 commits May 26, 2026 16:47

fix(Unleash): clear client reference on shutdown to prevent use-after…

f90a1db

…-dispose Nulling _clientTcs in ShutdownAsync ensures post-shutdown evaluations return ProviderNotReady instead of calling into the disposed client. Signed-off-by: PSanetra <code@psanetra.de>

feat(Unleash): honor cancellation tokens in resolve and shutdown methods

0ab267a

Use WaitAsync(cancellationToken) so awaiting the client task can be cancelled. Also target net8.0;net10.0 for both src and test projects. Signed-off-by: PSanetra <code@psanetra.de>

Merge remote-tracking branch 'origin/main' into feat/add-unleash-prov…

9765d96

…ider

PSanetra requested review from askpt and kylejuliandev May 29, 2026 08:36

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