[discourse] Flipt Cloud + OpenFeature + Go: internal error: proto: (line 1:205): unknown field "error"

[markphelps]

Originally posted by murph on Discourse

I’ve tried setting up Flipt Cloud + OpenFeature via go.

On my first flag evaluation, I get:

openfeature: GENERAL: internal error: proto: (line 1:205): unknown field “error”

I configured the client like so:

	fliptProvider := flipt.NewProvider(
		flipt.ForNamespace("features"),
		flipt.WithAddress("https://features-blahblah.flipt.cloud"),
		flipt.WithClientTokenProvider(sdk.StaticClientTokenProvider("this-is-my-api-key")),
	)
	lo.Must0(openfeature.SetProvider(fliptProvider))
	flagClient := openfeature.NewClient("this-is-my-service-name")

And i try to evaluate the flag like this:

color, err := s.flagClient.StringValue(ctx, "prototype-color", "orange", openfeature.NewEvaluationContext(
		"test-user-id",
		map[string]interface{}{},
	))

Any idea what I’ve done wrong? It looks like there’s some error that the SDk isn’t handling or propogating?

[dosubot[bot]]

The error unknown field "error" happens because the Flipt proto definitions for evaluation responses do not include an error field—error information is returned in an error_response field as part of a oneof in the EvaluationResponse message. If your client expects or tries to parse an error field, or if the server sends one, you'll get this deserialization error. This usually means there's a mismatch between the client and server proto definitions, or the client is using a stale or incompatible SDK or generated code. Make sure your client and any generated proto code are up to date and match the Flipt Cloud API schema, and that you are not expecting or sending an error field in evaluation messages—only error_response is valid for errors in this context. See the proto definitions for details on the expected structure and error handling approach (source).

If you are using a custom or older SDK, or have hand-written proto handling, double-check that your code aligns with the official proto schema. This kind of error is common when codegen or dependencies are out of sync with the server (source).

To reply, just mention @dosu.

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[markphelps]

Reply from mark on Discourse:

Hey @murph !

Thanks for detailed info and for trying out Flipt Cloud!!

Flipt Cloud currently works with our client-side evaluation SDKs only out of the box.

  <a href="https://docs.flipt.io/cloud/architecture#evaluation" target="_blank" rel="noopener">Flipt</a>

Architecture - Flipt

Learn about the architecture of Flipt Cloud and how it scales to meet your needs

The OpenFeature provider for Go only works for server-side evaluation, and uses our Go server-side SDK under the hood, so this won’t work with Flipt Cloud.

You could however use Flipt Cloud and Flipt Open Source in combination, which would give you ‘the best of both worlds’. Flipt Cloud can be used for creating/updating/deleting flags/segments/etc in the UI, that gets synced to your Git repository, then Flipt Open Source can be run and pointed at the same Git repository as it’s data source.

Then you could use any of our SDKs including the OpenFeature ones for evaluations against the open source Flipt that runs in your infrastructure.

We have a bit of detail on this pattern in our docs: Architecture - Flipt

Hope this helps!

Mark