OpenFeature Ruby SDK

Quick start

Requirements

Supported Ruby Version	OS
Ruby 3.1.4	Windows, MacOS, Linux
Ruby 3.2.3	Windows, MacOS, Linux
Ruby 3.3.0	Windows, MacOS, Linux

Install

Install the gem and add to the application's Gemfile by executing:

bundle add openfeature-sdk

If bundler is not being used to manage dependencies, install the gem by executing:

gem install openfeature-sdk

Usage

require 'open_feature/sdk'
require 'json' # For JSON.dump

# API Initialization and configuration

OpenFeature::SDK.configure do |config|
  # your provider of choice, which will be used as the default provider
  config.set_provider(OpenFeature::SDK::Provider::InMemoryProvider.new(
    {
      "flag1" => true,
      "flag2" => 1
    }
  ))
end

# Create a client
client = OpenFeature::SDK.build_client

# fetching boolean value feature flag
bool_value = client.fetch_boolean_value(flag_key: 'boolean_flag', default_value: false)

# a details method is also available for more information about the flag evaluation
# see `ResolutionDetails` for more info
bool_details = client.fetch_boolean_details(flag_key: 'boolean_flag', default_value: false) ==

# fetching string value feature flag
string_value = client.fetch_string_value(flag_key: 'string_flag', default_value: false)

# fetching number value feature flag
float_value = client.fetch_number_value(flag_key: 'number_value', default_value: 1.0)
integer_value = client.fetch_number_value(flag_key: 'number_value', default_value: 1)

# get an object value
object = client.fetch_object_value(flag_key: 'object_value', default_value: JSON.dump({ name: 'object'}))

Features

Status	Features	Description
✅	Providers	Integrate with a commercial, open source, or in-house feature management tool.
✅	Targeting	Contextually-aware flag evaluation using evaluation context.
⚠️	Hooks	Add functionality to various stages of the flag evaluation life-cycle.
❌	Logging	Integrate with popular logging packages.
✅	Domains	Logically bind clients with providers.
❌	Eventing	React to state changes in the provider or flag management system.
⚠️	Shutdown	Gracefully clean up a provider during application shutdown.
❌	Transaction Context Propagation	Set a specific evaluation context for a transaction (e.g. an HTTP request or a thread)
⚠️	Extending	Extend OpenFeature with custom providers and hooks.

_{Implemented: ✅ | In-progress: ⚠️ | Not implemented yet: ❌}

Providers

Providers are an abstraction between a flag management system and the OpenFeature SDK. Look here for a complete list of available providers. If the provider you're looking for hasn't been created yet, see the develop a provider section to learn how to build it yourself.

Once you've added a provider as a dependency, it can be registered with OpenFeature like this:

OpenFeature::SDK.configure do |config|
  # your provider of choice, which will be used as the default provider
  config.set_provider(OpenFeature::SDK::Provider::InMemoryProvider.new(
    {
      "v2_enabled" => true,
    }
  ))
end

In some situations, it may be beneficial to register multiple providers in the same application. This is possible using domains, which is covered in more detail below.

Targeting

Sometimes, the value of a flag must consider some dynamic criteria about the application or user, such as the user's location, IP, email address, or the server's location. In OpenFeature, we refer to this as targeting. If the flag management system you're using supports targeting, you can provide the input data using the evaluation context.

OpenFeature::SDK.configure do |config|
  # you can set a global evaluation context here
  config.evaluation_context = OpenFeature::SDK::EvaluationContext.new("host" => "myhost.com")
end

# Evaluation context can be set on a client as well
client_with_context = OpenFeature::SDK.build_client(
  evaluation_context: OpenFeature::SDK::EvaluationContext.new("controller_name" => "admin")
)

# Invocation evaluation context can also be passed in during flag evaluation.
# During flag evaluation, invocation context takes precedence over client context
# which takes precedence over API (aka global) context.
bool_value = client.fetch_boolean_value(
  flag_key: 'boolean_flag',
  default_value: false,
  evaluation_context: OpenFeature::SDK::EvaluationContext.new("is_friday" => true)
)

Hooks

Coming Soon! Issue available to be worked on.

Logging

Coming Soon! Issue available to work on.

Domains

Clients can be assigned to a domain. A domain is a logical identifier which can be used to associate clients with a particular provider. If a domain has no associated provider, the default provider is used.

OpenFeature::SDK.configure do |config|
  config.set_provider(OpenFeature::SDK::Provider::NoOpProvider.new, domain: "legacy_flags")
end

# Create a client for a different domain, this will use the provider assigned to that domain
legacy_flag_client = OpenFeature::SDK.build_client(domain: "legacy_flags")

Eventing

Coming Soon! Issue available to be worked on.

Shutdown

Coming Soon! Issue available to be worked on.

Transaction Context Propagation

Coming Soon! Issue available to be worked on.

Extending

Develop a provider

To develop a provider, you need to create a new project and include the OpenFeature SDK as a dependency. This can be a new repository or included in the existing contrib repository available under the OpenFeature organization. You’ll then need to write the provider by implementing the Provider duck.

class MyProvider
  def init
    # Perform any initialization steps with flag management system here
    # Return value is ignored
    # **Note** The OpenFeature spec defines a lifecycle method called `initialize` to be called when a new provider is set.
    # To avoid conflicting with the Ruby `initialize` method, this method should be named `init` when creating a provider.
  end

  def shutdown
    # Perform any shutdown/reclamation steps with flag management system here
    # Return value is ignored
  end

  def fetch_boolean_value(flag_key:, default_value:, evaluation_context: nil)
    # Retrieve a boolean value from provider source
  end

  def fetch_string_value(flag_key:, default_value:, evaluation_context: nil)
    # Retrieve a string value from provider source
  end

  def fetch_number_value(flag_key:, default_value:, evaluation_context: nil)
    # Retrieve a numeric value from provider source
  end

  def fetch_integer_value(flag_key:, default_value:, evaluation_context: nil)
    # Retrieve a integer value from provider source
  end

  def fetch_float_value(flag_key:, default_value:, evaluation_context: nil)
    # Retrieve a float value from provider source
  end

  def fetch_object_value(flag_key:, default_value:, evaluation_context: nil)
    # Retrieve a hash value from provider source
  end
end

Built a new provider? Let us know so we can add it to the docs!

Develop a hook

Coming Soon! Issue available to be worked on.