LaunchDarkly Developer Documentation

Get started in under 30 minutes.
LaunchDarkly provides feature flags as a service for Java · Python · Ruby · Go · Node.js · PHP · .NET. Control feature launches -- who sees what and when -- without multiple code deploys. Easy dashboard for phased rollouts, targeting and segmenting.
Need more help? write us at

Get Started    Documentation

Roku SDK Reference

This reference guide documents basic usage of our Roku SDK, and explains in detail how features work. If you want to dig even deeper, our SDKs are open source-- head to our Roku Client Github repository to look under the hood. The complete API reference is available here. Additionally you can clone and run a sample application using this SDK.

The Roku SDK is written in BrightScript.

Getting started

Building on top of our Quickstart guide, the following steps will get you started with using the LaunchDarkly SDK in your Roku Application.

We provide releases on GitHub. Download the latest release and extract the provided files into your source tree. You may need to rename the paths inside LaunchDarklyTask.xml depending on your project structure.

For SceneGraph usage add a LaunchDarklyTask node to your scene and then:

REM get a reference to to task
launchDarklyNode ="my-node-name")
REM create configuration
config = LaunchDarklyConfig("MY_MOBILE_KEY", launchDarklyNode)
REM create a user
user = LaunchDarklyUser("user-key")
REM initialize the client
LaunchDarklySGInit(config, user)

For each SceneGraph component you want to use the SDK in you need to initialize an interface to talk to the SceneGraph. This interface provides all the expected client functionality such as evaluation.

REM create the scenegraph communication wrapper
launchDarkly = LaunchDarklySG(launchDarklyNode)
REM use the client
value = launchDarkly.boolVariation("MY_FLAG_KEY", false)

Creating a client outside of the SceneGraph API is similar. In the legacy API you do not need LaunchDarklySGInit or the LaunchDarklySG functions.

REM get a reference to the task
launchDarklyNode ="MY_NODE_NAME")
REM create configuration
config = LaunchDarklyConfig("MY_MOBILE_KEY", launchDarklyNode)
REM create a user
user = LaunchDarklyUser("user-key")

REM create message port
messagePort = createObject("roMessagePort")
REM initialize the client
launchDarkly = LaunchDarkly(config, user, messagePort)

REM use the client
value = launchDarkly.boolVariation("MY_FLAG_KEY", false)

If not using the SceneGraph you need to poll events to drive the client in your standard event loop.

while (true)
    REM do not wait forever or timers will break
    msg = wait(3000, messagePort)
    if launchDarkly.handleMessage(msg) then
        REM this message was for the client
        REM handle non client messages
    end if
end while


The *variation methods determine which variation of a feature flag a user receives.

REM typed variations
myInt = launchDarkly.intVariation("MY_FLAG_KEY", 123)
myBool = launchDarkly.boolVariation("MY_FLAG_KEY", false)
myString = launchDarkly.stringVariation("MY_FLAG_KEY", "hello world!")
myObjectOrArray = launchDarkly.jsonVariation("MY_FLAG_KEY", {"value": 123})
REM generic variation
myValue = launchDarkly.variation("MY_FLAG_KEY", false)

*variation calls take a feature flag key and a default value.

The default value will only be returned if an error is encountered—for example, if the feature flag key doesn't exist or the user doesn't have a key specified.

Evaluation explanations

For each variation type there is also an associated version that returns the reason a particular value was returned. For example:

details = launchDarkly.intVariationDetail("MY_FLAG_KEY", 123)

These variation methods return an object containing the keys value, reason, and variationIndex. The value field is the result of the evaluation. The reason field is an object that explains why the result happened, for example details about a rule match. The reason object will always contain a kind field. Lastly the (potentially null) variationIndex field contains the id of the particular value returned.

Customizing your client

You can create a client configuration object with:

REM for a legacy Roku application
config = LaunchDarklyConfig("YOUR_MOBILE_KEY")
REM for a SceneGraph Roku Application

We support the following configuration options for both SceneGraph and non SceneGraph usage:






Log levels

You can configure the SDK log level. For example to set the level to info:


The SDK supports the following Levels:


A custom logging backend can be provided. This will be different depending on if you are using the SceneGraph API or the Legacy API.

Legacy API Custom Logger

function CustomLogger() as Object
    return {
        log: function(level as Integer, message as String)
            print level message
        end function
end function


SceneGraph API Custom Logger

<!-- /components/CustomLogger.xml -->

<component name="CustomLogger" extends="Task">
        <field id="log" type="assocarray" alwaysNotify="true"/>
    <script type="text/brightscript" uri="pkg:/components/CustomLogger.brs"/>
REM /components/CustomLogger.brs

function init()
    m.messagePort = createObject("roMessagePort")"log", m.messagePort)
end function

function mainThread() as Void
    while (true)
        msg = wait(0, m.messagePort)

        if type(msg) = "roSGNodeEvent" then
            if field = "log" then
                value = msg.getData()
                print value.level value.message
            end if
        end if
    end while
end function

To use the logger create the SceneGraph logger node and then:



You can create a user object with:

user = LaunchDarklyUser("my-user-key")

User objects can be customized with:


A user can be marked as anonymous with:


Users can have specific fields marked as private with:



The track method allows you to record custom events in your application with LaunchDarkly:

REM without optional data
REM with optional data
launchDarkly.track("YOUR_EVENT_KEY", {"customField": 123})
REM with optional numeric metric
launchDarkly.track("YOUR_EVENT_KEY", invalid, 52.3)


Internally, the LaunchDarkly SDK keeps an event buffer for analytics events. These are flushed periodically in a background thread. In some situations (for example, if you're testing out the SDK in a simulator), you may want to manually call flush to process events immediately.


Changing the user context

If your app is used by multiple users on a single device, you may want to change users and have separate flag settings for each user. To achieve this, the SDK supports switching between different user contexts.

user = LaunchDarklyUser("abc")

The identify call will load any saved flag values for the new user and immediately trigger an update of the latest flags from LaunchDarkly. Since this method re-fetches flag settings for the new user, it should not be called at high frequency. The intended use case for switching user contexts is the login / logout flow.

Getting all flags

You can get an associative array of flagKey -> flagValue for all flags from the client with:

allFlags = launchDarkly.allFlags()

Roku SDK Reference

Suggested Edits are limited on API Reference Pages

You can only suggest edits to Markdown body content, but not to the API spec.