Experiment Go SDK

Official documentation for Amplitude Experiment's server-side Go SDK implementation.

This documentation is split into two sections for remote and local evaluation:

• Remote evaluation
• Local evaluation

Remote evaluation¶

Implements fetching variants for a user via remote evaluation.

Install¶

Install the Go Server SDK using go get.

go get github.com/amplitude/experiment-go-server

// (1) Initialize the local evaluation client with a server deployment key.
client := remote.Initialize("<DEPLOYMENT_KEY>", nil)

// (2) Fetch variants for a user
user := &experiment.User{
  UserId:   "user@company.com",
  DeviceId: "abcdefg",
  UserProperties: map[string]interface{}{
    "premium": true,
  },
}
variants, err := client.Fetch(user)
if err != nil {
  // Handle error
}

// (3) Access a flag's variant
variant := variants["<FLAG_KEY>"]
if variant.Value == "on" {
    // Flag is on
} else {
    // Flag is off
}

Initialize¶

The SDK client should be initialized in your server on startup. The deployment key argument passed into the apiKey parameter must live within the same project that you are sending analytics events to.

func Initialize(apiKey string, config *Config) *Client

client := remote.Initialize("<DEPLOYMENT_KEY>", nil)

Configuration¶

The SDK client can be configured on initialization.

Fetch¶

Fetches variants for a user and returns the results. This function remote evaluates the user for flags associated with the deployment used to initialize the SDK client.

func (c *Client) Fetch(user *experiment.User) (map[string]experiment.Variant, error)

user := &experiment.User{
    UserId:   "user@company.com",
    DeviceId: "abcdefg",
    UserProperties: map[string]interface{}{
        "premium": true,
    },
}
variants, err := client.Fetch(user)
if err != nil {
    // Handle error
}

After fetching variants for a user, you may to access the variant for a specific flag.

variant := variants["<FLAG_KEY>"]
if variant.Value == "on" {
    // Flag is on
} else {
    // Flag is off
}

Local evaluation¶

Implements evaluating variants for a user via local evaluation. If you plan on using local evaluation, you should understand the tradeoffs.

Install¶

Install the Go Server SDK using go get.

go get github.com/amplitude/experiment-go-server

// (1) Initialize the local evaluation client with a server deployment key.
client := local.Initialize("<DEPLOYMENT_KEY>", nil)

// (2) Start the local evaluation client.
err := client.Start()
if err != nil {
  panic(err)
}

  // (3) Evaluate a user.
user := &experiment.User{DeviceId: "abcdefg"}
variants, err := client.EvaluateV2(user, nil)
if err != nil {
  panic(err)
}

Initialize¶

Initializes a local evaluation client.

func Initialize(apiKey string, config *Config) *Client

Configuration¶

The SDK client can be configured on initialization.

Start¶

Start the local evaluation client, pre-fetching local evaluation mode flag configs for evaluation and starting the flag config poller at the configured interval.

func (c *Client) Start() error

You should await the result of Start() to ensure that flag configs are ready to be used before calling Evaluate()

err := client.Start()
if err != nil {
    panic(err)
}

Evaluate¶

Executes the evaluation logic using the flags pre-fetched on Start(). Evaluate must be given a user object argument and can optionally be passed an array of flag keys if only a specific subset of required flag variants are required.

func (c *Client) EvaluateV2(user *experiment.User, flagKeys []string) (map[string]experiment.Variant, error)

// The user to evaluate
user := &experiment.User{DeviceId: "abcdefg"}

// Evaluate all flag variants
allVariants, err := client.EvaluateV2(user, nil)
if err != nil {
    // Handle Error
}

// Evaluate a specific subset of flag variants
specificVariants, err := client.EvaluateV2(user, []string{
    "<FLAG_KEY_1>",
    "<FLAG_KEY_2>",
})

// Access a variant
variant := allVariants["<FLAG_KEY>"]
if variant.Value == "on" {
    // Flag is on
} else {
    // Flag is off
}