flagbearer for PHP

The PHP SDK for Flagbearer. Requires PHP 8.1 or later with the curl, json and mbstring extensions.

Install

composer require flagbearer/flagbearer

Keys

Use a server key, which starts with fbs_. Server keys are secret: read them from the environment, such as FLAGBEARER_SERVER_KEY, and never put them in browser code or in the repository. Browsers use client keys, which start with fbc_, through @flagbearer/web.

Pick a cache

Pass a cache shared between requests with the cache option. It accepts any PSR-16 cache:

• APCu or Redis in production, through any PSR-16 adapter, such as symfony/cache (Psr16Cache around ApcuAdapter or RedisAdapter) or Laravel's cache store.
• Flagbearer\Cache\FileCache when neither is available.
• Flagbearer\Cache\MemoryCache, the default, only for long-running workers such as RoadRunner, Swoole or FrankenPHP's worker mode. Under PHP-FPM, always pass a shared cache.

Check per request

Create the client once per request, or once per worker, and check flags with the user and a default:

use Flagbearer\Cache\FileCache;
use Flagbearer\Client;
use Flagbearer\Options;

$flags = Client::create(getenv('FLAGBEARER_SERVER_KEY'), new Options(
    cache: new FileCache(sys_get_temp_dir() . '/flagbearer'),
));

$user = ['key' => $currentUser->id, 'email' => $currentUser->email];
if ($flags->isEnabled('advanced-search', $user, false)) {
    // …
}

The default is used until the client has synced, and when the flag doesn't exist. The user can also be a Flagbearer\User. The email is optional. Include it to turn flags on for testers by email.

Long-running workers that keep one client across requests should call $flags->flush() after each request.

Laravel

Register the client as a singleton in a service provider, using Laravel's cache (Redis, Memcached or APCu are best):

namespace App\Providers;

use Flagbearer\Client;
use Flagbearer\Options;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\ServiceProvider;

class FlagbearerServiceProvider extends ServiceProvider
{
    public function register(): void
    {
        $this->app->singleton(Client::class, fn () => Client::create(
            config('services.flagbearer.key'),
            new Options(cache: Cache::store()),
        ));
    }
}

public function search(Request $request, Client $flags)
{
    $user = ['key' => (string) $request->user()->id, 'email' => $request->user()->email];
    $advanced = $flags->isEnabled('advanced-search', $user, false);
    // …
}

Laravel's cache store implements PSR-16, so it can be passed directly. Add 'flagbearer' => ['key' => env('FLAGBEARER_SERVER_KEY')] to config/services.php.