Go - Fireweave

The Go module is github.com/FireWeave-HQ/fireweave-sdk/sdks/go/v2. It evaluates control points through client.ControlPoints() and registers targets through client.RegisterTarget. Those are the two v1 capabilities. The wire protocol uses flagKey. The /v2 suffix is required in both go get and import paths. sdks/go/v2.2.0 does not resolve — pin v2.3.0 or later.

Supported versions

From go.mod:

	Value
Module	`github.com/FireWeave-HQ/fireweave-sdk/sdks/go/v2`
Published	v2.3.0
`go` directive	`1.25.13`
Runtime dependencies	none (standard library only)

Install

go get github.com/FireWeave-HQ/fireweave-sdk/sdks/go/v2@v2.3.0

import "github.com/FireWeave-HQ/fireweave-sdk/sdks/go/v2/fireweave"

Callers import the fireweave façade only. Init is the composition root.

Initialize

fireweave.Init is the single entry point. Mode is required and never inferred. Init returns a non-nil error (kind Configuration) when mode is missing, remote credentials are blank, APIURL fails the host allowlist, or local mode is combined with credentials.

package main

import (
	"context"
	"fmt"

	"github.com/FireWeave-HQ/fireweave-sdk/sdks/go/v2/fireweave"
)

func main() {
	client, err := fireweave.Init(fireweave.Options{
		Mode: fireweave.ModeLocal,
		Local: &fireweave.LocalOptions{
			ControlPoints: map[string]bool{"new-checkout": true},
		},
	})
	if err != nil {
		panic(err)
	}

	evalCtx := fireweave.NewEvaluationContext("user_42", nil)
	enabled := client.ControlPoints().GetBooleanValue("new-checkout", false, &evalCtx)
	fmt.Println("new-checkout:", enabled)

	_ = client.Runtime().Shutdown(context.Background())
}

Production:

client, err := fireweave.Init(fireweave.Options{
	Mode:   fireweave.ModeRemote,
	APIKey: os.Getenv("FW_PROJECT_API_KEY"),
	APIURL: os.Getenv("FW_API_URL"),
})

The SDK reads no environment variables. os.Getenv in the snippet is your app, not the SDK. Public ControlPoints() methods and RegisterTarget do not take context.Context. They call the runtime with context.Background(). The remote adapter’s configured request timeout bounds the HTTP call. Runtime and Client are safe for concurrent use.

Configuration and authentication

Options on Init:

Field	Mode	Description
`Mode`	both	`ModeLocal` or `ModeRemote` (required)
`APIURL`	`remote`	fw-server base URL (required)
`APIKey`	`remote`	Fireweave project key (required)
`AllowedHosts`	`remote`	SSRF allowlist override
`Local.ControlPoints`	`local`	Seeded boolean map
`Local.Log`	`local`	Sink for the `[fireweave:local]` trace

Default allowlist (infrastructure/adapters/remote.DefaultAllowedHosts) is Fireweave production/staging hosts plus loopback. It is not derived from your APIURL hostname. A self-hosted fw-server must list its own host, or pass AllowedHosts: []string{"*"}. Auth: Authorization: Bearer <key>. Paths: POST /v1/flags/evaluate, POST /v1/targets/register. See Configuration and auth.

Targets

RegisterTarget is on the client.

registered := client.RegisterTarget("user_42", &fireweave.RegisterTargetOptions{
	Kind:       fireweave.TargetKindUser,
	Properties: map[string]any{"plan": "pro", "region": "eu-west"},
})
if !registered.OK {
	fmt.Println("registerTarget failed", registered.Error)
}

opts may be nil. The call never panics. In local mode the adapter records the target in-process and traces [fireweave:local]. See Targeting and targets.

Control points

client.ControlPoints() is the documented namespace. client.Flags() is the same object (deprecated alias, silent at runtime). FlagType: FlagTypeBoolean, FlagTypeString, FlagTypeNumber, FlagTypeObject. There is no separate integer/float type in v1.

evalCtx := fireweave.NewEvaluationContext("user_42", map[string]any{"tier": "pro"})

on := client.ControlPoints().GetBooleanValue("new-checkout", false, &evalCtx)
theme := client.ControlPoints().GetStringValue("theme", "light", &evalCtx)

details := client.ControlPoints().GetBooleanDetails("new-checkout", false, &evalCtx)
if details.Error != nil {
	fmt.Printf("default %v (%s)\n", details.Value, details.Error.Kind)
}

decision := client.ControlPoints().Evaluate(
	"new-checkout",
	fireweave.FlagTypeBoolean,
	false,
	&evalCtx,
	nil,
)

Nine methods: GetBooleanValue, GetStringValue, GetNumberValue, GetObjectValue, GetBooleanDetails, GetStringDetails, GetNumberDetails, GetObjectDetails, Evaluate. Evaluation never returns an error and never panics — failures are Decision{Reason: ERROR}. EvaluateOptions has one real field: IncludePayload. See Control points.

Adapters

Package	Use
`…/v2/infrastructure/adapters/remote`	Production fw-server
`…/v2/infrastructure/adapters/local`	Dev boolean seed (`Init` `Mode: local`)
`…/v2/infrastructure/adapters/inmemory`	Tests / conformance fixtures

Prefer fireweave.Init. Construct adapters directly only for custom wiring. See Adapters.

Errors

fireweave.Error with ErrorKind constants — the same 15 kinds. Implements error. Evaluation still returns a Decision; Init and Runtime.Shutdown return error. See Errors.

Testing

Local mode for an offline boolean seed. infrastructure/adapters/inmemory with WithFlags for fixture-driven tests. The test-server stub does not implement target registration. See Testing.

Shutdown

There is no Client.Shutdown. Shut down the runtime:

shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
_ = client.Runtime().Shutdown(shutdownCtx)

See Initialize, ready, shutdown.

Not in this SDK

An unsuffixed …/sdks/go module path
FireweaveProvider / any OpenFeature package
Releases(), Exposures(), Signals(), Capabilities(), Guardrails()
Environment-variable auto-read
context.Context on ControlPoints() / RegisterTarget

Quickstart

Offline evaluate in every language.

Compatibility

Seven-language surface and the 65×7 aggregate.

Get Started

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Reference

Go

Supported versions

Install

Initialize

Configuration and authentication

Targets

Control points

Adapters

Errors

Testing

Shutdown

Not in this SDK

Next

Quickstart

Compatibility

​Supported versions

​Install

​Initialize

​Configuration and authentication

​Targets

​Control points

​Adapters

​Errors

​Testing

​Shutdown

​Not in this SDK

​Next

Quickstart

Compatibility

Supported versions

Install

Initialize

Configuration and authentication

Targets

Control points

Adapters

Errors

Testing

Shutdown

Not in this SDK

Next