# Flags SDK - LaunchDarkly Provider

The [LaunchDarkly provider](https://flags-sdk.dev/docs/api-reference/adapters/launchdarkly) for the [Flags SDK](https://flags-sdk.dev/) contains support for LaunchDarkly's Feature Flags.

## Setup

The Statsig provider is available in the `@flags-sdk/statsig` module. You can install it with

```bash
npm i @flags-sdk/launchdarkly
```

## Provider Instance

**NOTE:** The [LaunchDarkly Vercel integration](https://vercel.com/integrations/launchdarkly) must be installed on your account, as this adapter loads LaunchDarkly from Global Config. The adapter can not be used without Global Config.

Import the default adapter instance `ldAdapter` from `@flags-sdk/launchdarkly`:

```ts
import { ldAdapter } from "@flags-sdk/launchdarkly";
```

The default adapter uses the following environment variables to configure itself:

```sh
export LAUNCHDARKLY_CLIENT_SIDE_ID="612376f91b8f5713a58777a1"
export LAUNCHDARKLY_PROJECT_SLUG="my-project"
# Provided by the LaunchDarkly Marketplace integration when Global Config is
# enabled for the collection.
export EXPERIMENTATION_CONFIG="https://global-config.vercel.com/ecfg_abdc1234?token=xxx-xxx-xxx"
```

> **Using the legacy LaunchDarkly Vercel integration?** The default adapter reads
> the Global Config connection string from `EXPERIMENTATION_CONFIG` only. If your
> project provides the connection string as `GLOBAL_CONFIG`, set
> `EXPERIMENTATION_CONFIG` to the same value, or pass it explicitly with
> [`createLaunchDarklyAdapter`](#custom-adapter).

## Example

```ts
import { flag, dedupe } from "flags/next";
import { ldAdapter, type LDContext } from "@flags-sdk/launchdarkly";

const identify = dedupe(async (): Promise<LDContext> => {
  return {
    key: "user_123",
  };
});

export const showBanner = flag<boolean, LDContext>({
  key: "show-banner",
  identify,
  adapter: ldAdapter.variation(),
});
```

## Custom Adapter

Create an adapter by using the `createLaunchDarklyAdapter` function:

```ts
import { createLaunchDarklyAdapter } from "@flags-sdk/launchdarkly";

const adapter = createLaunchDarklyAdapter({
  projectSlug: "my-project",
  clientSideId: "612376f91b8f5713a58777a1",
  // Legacy integrations that provide the connection string as `GLOBAL_CONFIG`
  // can pass it explicitly here.
  globalConfigConnectionString:
    process.env.EXPERIMENTATION_CONFIG ?? process.env.GLOBAL_CONFIG,
});
```

## Documentation

Please check out the [LaunchDarkly provider documentation](https://flags-sdk.dev/docs/api-reference/adapters/launchdarkly) for more information.