---
sidebar_position: 20
title: GO
description: How to use the OpenFeature GO SDK
---

# GO SDK usage

## Install dependencies

The first things we will do is install the **Open Feature SDK** and the **GO Feature Flag provider**.

```shell
go get github.com/open-feature/go-sdk
go get github.com/open-feature/go-sdk-contrib/providers/go-feature-flag
```

## Initialize your Open Feature provider

Despite other providers, this GO provider can be used with the **relay proxy** or standalone
using the **GO Feature Flag module**.

### Using the relay proxy

If you want to use the provider with the **relay proxy** you should set the field `Endpoint` in the options.
By default it will use a default `HTTPClient` with a **timeout** configured at **10000** milliseconds. You can change
this configuration by providing your own configuration of the `HTTPClient`.

#### Example
```go
options := gofeatureflag.ProviderOptions{
  Endpoint: "http://localhost:1031",
  HTTPClient: &http.Client{
    Timeout:   1 * time.Second,
  },
}
provider, _ := gofeatureflag.NewProvider(options)
```

### Using the GO module _(standalone version)_
If you want to use the provider in standalone mode using the GO module, you should set the field `GOFeatureFlagConfig`
in the options.

You can check the [GO Feature Flag documentation website](https://docs.gofeatureflag.org) to look how to configure the
GO module.

#### Example
```go
options := gofeatureflag.ProviderOptions{
  GOFeatureFlagConfig: &ffclient.Config{
      PollingInterval: 10 * time.Second,
      Context:         context.Background(),
      Retriever: &fileretriever.Retriever{
        Path: "../testutils/module/flags.yaml",
      },
    },
}
provider, _ := gofeatureflag.NewProvider(options)
```

## Initialize your Open Feature client

To evaluate the flags you need to have an Open Feature configured in you app.
This code block shows you how you can create a client that you can use in your application.

```go
import (
  // ...
  gofeatureflag "github.com/open-feature/go-sdk-contrib/providers/go-feature-flag/pkg"
  of "github.com/open-feature/go-sdk/pkg/openfeature"
)

// ...

options := gofeatureflag.ProviderOptions{
    Endpoint: "http://localhost:1031",
}
provider, err := gofeatureflag.NewProvider(options)
of.SetProvider(provider)
client := of.NewClient("my-app")
```

## Evaluate your flag

This code block explain how you can create an `EvaluationContext` and use it to evaluate your flag.


> In this example we are evaluating a `boolean` flag, but other types are also available.
>
> **Refer to the [Open Feature documentation](https://docs.openfeature.dev/docs/reference/concepts/evaluation-api#basic-evaluation) to know more about it.**

```go
evaluationCtx := of.NewEvaluationContext(
    "1d1b9238-2591-4a47-94cf-d2bc080892f1",
    map[string]interface{}{
      "firstname", "john",
      "lastname", "doe",
      "email", "john.doe@gofeatureflag.org",
      "admin", true,
      "anonymous", false,
    })
adminFlag, _ := client.BoolValue(context.TODO(), "flag-only-for-admin", false, evaluationCtx)
if adminFlag {
   // flag "flag-only-for-admin" is true for the user
} else {
  // flag "flag-only-for-admin" is false for the user
}
```

## Contribute to the provider
You can find the source of the provider in the [`open-feature/go-sdk-contrib`](https://github.com/open-feature/go-sdk-contrib/tree/main/providers/go-feature-flag) repository.