LaunchDarkly OpenFeature provider for the Server-Side SDK for Ruby

Gem Version

Run CI RubyDoc GitHub Pages

This provider allows for using LaunchDarkly with the OpenFeature SDK for Ruby.

This provider is designed primarily for use in multi-user systems such as web servers and applications. It follows the server-side LaunchDarkly model for multi-user contexts. It is not intended for use in desktop and embedded systems applications.

[!WARNING] This is a beta version. The API is not stabilized and may introduce breaking changes.

[!NOTE] This OpenFeature provider uses production versions of the LaunchDarkly SDK, which adhere to our standard versioning policy.

LaunchDarkly overview

LaunchDarkly is a feature management platform that serves trillions of feature flags daily to help teams build better software, faster. Get started using LaunchDarkly today!

Twitter Follow

Supported Ruby versions

This version of the LaunchDarkly provider works with Ruby 3.4 and above.

Feature matrix

This matrix mirrors the feature matrix of the OpenFeature SDK for Ruby and describes what this provider supports. Rows which are not supported state whether the limitation comes from the OpenFeature Ruby SDK or from the provider.

Status Feature Notes
✅ Providers Evaluates boolean, string, integer, float, number, and object flags through the LaunchDarkly Ruby SDK.
✅ Targeting The EvaluationContext is converted to a LaunchDarkly single or multi-context. See OpenFeature Specific Considerations.
✅ Hooks Hooks are registered on the OpenFeature API and client; the provider requires no additional support and its results are visible to hooks, including flag metadata.
✅ Logging The provider logs through the logger of the LaunchDarkly::Config it is given.
✅ Domains Domains bind clients to providers in the OpenFeature SDK; a separate provider instance may be registered per domain.
✅ Eventing LaunchDarkly data source status changes are emitted as PROVIDER_READY, PROVIDER_STALE, and PROVIDER_ERROR. Flag changes are emitted as PROVIDER_CONFIGURATION_CHANGED with the changed flag key.
✅ Initialization init reports whether the LaunchDarkly client became ready within the configured wait time; a failure results in the ERROR state so that cached or fallback flag data is still evaluated.
✅ Shutdown shutdown closes the LaunchDarkly client. A closed client cannot be restarted, so a new provider instance is required afterward.
✅ Tracking track sends a LaunchDarkly custom event for the evaluation context, with the tracking event value and remaining details attached.
✅ Transaction Context Propagation Provided by the OpenFeature SDK, which merges the transaction context into the evaluation context before the provider is called; no provider support is required.
✅ Extending This provider is itself an extension of the OpenFeature SDK. The underlying LaunchDarkly client is available through provider.client for functionality with no OpenFeature equivalent.
✅ Flag metadata LaunchDarkly evaluation reason details are returned as OpenFeature flag metadata. See Flag Metadata.

Supported: ✅ | Partially supported: ⚠️ | Not supported: ❌

Getting started

Requisites

Install the library

$ gem install launchdarkly-openfeature-server-sdk

Usage

require 'open_feature/sdk'
require 'ldclient-rb'
require 'ldclient-openfeature'

provider = LaunchDarkly::OpenFeature::Provider.new(
  'sdk-key',
  LaunchDarkly::Config.new
)

OpenFeature::SDK.configure do |config|
  config.set_provider(provider)
end

# Refer to OpenFeature documentation for getting a client and performing evaluations.

Refer to the SDK reference guide for instructions on getting started with using the SDK.

For information on using the OpenFeature client please refer to the OpenFeature Documentation.

OpenFeature Specific Considerations

LaunchDarkly evaluates contexts, and it can either evaluate a single-context, or a multi-context. When using OpenFeature both single and multi-contexts must be encoded into a single EvaluationContext. This is accomplished by looking for an attribute named kind in the EvaluationContext.

There are 4 different scenarios related to the kind:

  1. There is no kind attribute. In this case the provider will treat the context as a single context containing a "user" kind.
  2. There is a kind attribute, and the value of that attribute is "multi". This will indicate to the provider that the context is a multi-context.
  3. There is a kind attribute, and the value of that attribute is a string other than "multi". This will indicate to the provider a single context of the kind specified.
  4. There is a kind attribute, and the attribute is not a string. In this case the value of the attribute will be discarded, and the context will be treated as a "user". An error message will be logged.

The kind attribute should be a string containing only contain ASCII letters, numbers, ., _ or -.

The OpenFeature specification allows for an optional targeting key, but LaunchDarkly requires a key for evaluation. A targeting key must be specified for each context being evaluated. It may be specified using either targeting_key, as it is in the OpenFeature specification, or key, which is the typical LaunchDarkly identifier for the targeting key. If a targeting_key and a key are specified, then the targeting_key will take precedence.

There are several other attributes which have special functionality within a single or multi-context.

  • A key of privateAttributes. Must be an array of string values.
  • A key of anonymous. Must be a boolean value.
  • A key of name. Must be a string.

Examples

A single user context

context = EvaluationContext(key: "the-key")

A single context of kind "organization"

context = EvaluationContext(key: "org-key", kind: "organization")

A multi-context containing a "user" and an "organization"

attributes = {
    kind: "multi",
    organization: {
        name: "the-org-name",
        key, "my-org-key",
        myCustomAttribute, "myAttributeValue"
    },
    user: {
        key: "my-user-key",
        anonymous, true
    }
}
context = EvaluationContext(**attributes)

Setting private attributes in a single context

attributes = {
    key: "org-key",
    kind: "organization",
    myCustomAttribute: "myAttributeValue",
    privateAttributes: ["myCustomAttribute"]
}

context = EvaluationContext(**attributes)

Setting private attributes in a multi-context

attributes = {
    kind: "organization",
    organization: {
        name: "the-org-name",
        key: "my-org-key",
        # This will ONLY apply to the "organization" attributes.
        privateAttributes: ["myCustomAttribute"],
        # This attribute will be private.
        myCustomAttribute: "myAttributeValue",
    },
    user: [
        key: "my-user-key",
        anonymous = > true,
        # This attribute will not be private.
        myCustomAttribute: "myAttributeValue",
    ]
}

context = EvaluationContext(**attributes)

Flag Metadata

Evaluations include flag metadata for the LaunchDarkly specific parts of the evaluation result which have no OpenFeature equivalent. Each entry is absent when it does not apply to the evaluation.

Key Type Description
variationIndex integer The index of the returned variation. Absent for default values.
inExperiment boolean Present, and true, when the evaluation was part of an experiment.
ruleIndex integer The index of the rule that matched.
ruleId string The identifier of the rule that matched.
prerequisiteKey string The key of the prerequisite flag that failed.
bigSegmentsStatus string The status of the Big Segments query made during the evaluation. 
details = client.fetch_boolean_details(flag_key: "my-flag", default_value: false)
in_experiment = details.flag_metadata.fetch("inExperiment", false)

Learn more

Check out our documentation for in-depth instructions on configuring and using LaunchDarkly. You can also head straight to the complete reference guide for this SDK.

The authoritative description of all properties and methods is in the ruby documentation.

Contributing

We encourage pull requests and other contributions from the community. Check out our contributing guidelines for instructions on how to contribute to this SDK.

About LaunchDarkly

  • LaunchDarkly is a continuous delivery platform that provides feature flags as a service and allows developers to iterate quickly and safely. We allow you to easily flag your features and manage them from the LaunchDarkly dashboard. With LaunchDarkly, you can: 
    * Roll out a new feature to a subset of your users (like a group of users who opt-in to a beta tester group), gathering feedback and bug reports from real-world use cases.
* Gradually roll out a feature to an increasing percentage of users, and track the effect that the feature has on key metrics (for instance, how likely is a user to complete a purchase if they have feature A versus feature B?).
* Turn off a feature that you realize is causing performance problems in production, without needing to re-deploy, or even restart the application with a changed configuration file.
* Grant access to certain features based on user attributes, like payment plan (eg: users on the ‘gold’ plan get access to more features than users in the ‘silver’ plan). Disable parts of your application to facilitate maintenance, without taking everything offline.
  • LaunchDarkly provides feature flag SDKs for a wide variety of languages and technologies. Check out our documentation for a complete list.
  • Explore LaunchDarkly