Go SDK - OpenFeature integration

The openfeature/ sub-module wraps an initialized *nexus.Client in an OpenFeature provider. It is published as a separate Go module so you only pull in the OpenFeature SDK dependency if you need it.

Installation

Install both the core SDK and the provider sub-module:

go get gitlab.com/westyx/nexus/sdk/go@v0.10.1
go get gitlab.com/westyx/nexus/sdk/go/openfeature@v0.8.0

Usage

import (
    "context"
    "log"

    nexus "gitlab.com/westyx/nexus/sdk/go"
    nexusof "gitlab.com/westyx/nexus/sdk/go/openfeature"
    "github.com/open-feature/go-sdk/openfeature"
)

func main() {
    ctx, cancel := context.WithCancel(context.Background())
    defer cancel()

    // Initialize the Nexus client (performs a blocking sync on startup)
    client, err := nexus.NewClient(ctx, nexus.Config{
        BaseURL: "https://blue-ocean-a5rx7.westyx.dev",
        APIKey:  "wxs_...",
    })
    if err != nil {
        log.Fatal(err)
    }
    defer client.Close()

    // Register the Nexus provider with OpenFeature globally
    openfeature.SetProvider(nexusof.New(client))

    // Use the standard OpenFeature client
    ofClient := openfeature.NewClient("my-service")

    enabled, _ := ofClient.BooleanValue(ctx, "dark-mode", false, openfeature.EvaluationContext{})
    region, _  := ofClient.StringValue(ctx, "aws.region", "eu-west-1", openfeature.EvaluationContext{})
    limit, _   := ofClient.FloatValue(ctx, "rate.limit", 100.0, openfeature.EvaluationContext{})
    pageSize, _ := ofClient.IntValue(ctx, "page.size", 50, openfeature.EvaluationContext{})
    dbConf, _  := ofClient.ObjectValue(ctx, "db.config", nil, openfeature.EvaluationContext{})
}

Evaluation mapping

OpenFeature method	Nexus call	Miss behavior
`BooleanValue` / `BooleanEvaluation`	`client.GetFlag(key, default)`	returns default with `STATIC` reason
`StringValue` / `StringEvaluation`	`client.GetConfig(key)` cast to `string`	`FLAG_NOT_FOUND` if missing, `TYPE_MISMATCH` if wrong type
`FloatValue` / `FloatEvaluation`	`client.GetConfig(key)` cast to `float64`	`FLAG_NOT_FOUND` if missing, `TYPE_MISMATCH` if wrong type
`IntValue` / `IntEvaluation`	`client.GetConfig(key)` cast to `int64`	`FLAG_NOT_FOUND` if missing, `TYPE_MISMATCH` if wrong type
`ObjectValue` / `ObjectEvaluation`	`client.GetConfig(key)` returned as-is	`FLAG_NOT_FOUND` if missing

EvaluationContext is ignored. Nexus does not support per-user flag targeting. All successful evaluations return STATIC reason. The context parameter is accepted to satisfy the OpenFeature interface but has no effect.

Behavior notes

Boolean flags use GetFlag. All other types use GetConfig. GetFlag always returns a value (default on miss), so boolean evaluations never produce FLAG_NOT_FOUND.
JSON number types. Config values decoded from JSON are float64 by default (encoding/json behavior). IntEvaluation accepts both float64 (JSON numbers) and int64. FloatEvaluation accepts both float64 and float32.
No I/O in the provider. The provider is a thin delegation layer. All network activity (initial sync, background refresh, SSE stream) is handled by the *nexus.Client. The OpenFeature evaluation calls never block on network.
Provider metadata name is "Nexus".

Module path

gitlab.com/westyx/nexus/sdk/go/openfeature

Latest release: v0.8.0 (2026-06-16)

Overview

Backend SDKs

Browser SDKs

OpenFeature Providers

Go SDK - OpenFeature integration

Installation

Usage

Evaluation mapping

Behavior notes

Module path

​Installation

​Usage

​Evaluation mapping

​Behavior notes

​Module path

Installation

Usage

Evaluation mapping

Behavior notes

Module path