Feature Flag

This is a simple library to enable/disable features based on a set of rules.

Installation

composer require xepozz/feature-flag

Configuration

Choose the driver you want to use. Currently, the library supports the following drivers:

• InMemory - stores data in memory. This driver is used by default.
• Redis - stores data in Redis. Uses phpredis extension

InMemory

Configure the driver in the dependency injection container configuration file:

di.php

\Xepozz\FeatureFlag\Driver\InMemoryDriver::class => [
    '__construct()' => [
        'flags' => [
            155 => false,
            'feature_name' => true,
            FeaturesEnum::FEATURE_NAME => true,
        ],
    ],
],

Or with params.php:

'xepozz/feature-flag' => [
    'flags' => [
        155 => false,
        'feature_name' => true,
        FeaturesEnum::FEATURE_NAME => true,
    ],
],

Configuring the driver with params.php is only available for the InMemoryDriver.

Redis

Configure the driver in the dependency injection container configuration file:

di.php

\Xepozz\FeatureFlag\Driver\RedisDriver::class => function () {
    $redis = new Redis();
    $redis->pconnect(
        host: '127.0.0.1',
        port: 6379,
        timeout: 2.5,
    );

    return new \Xepozz\FeatureFlag\Driver\RedisDriver(redis: $redis, hashTableKey: 'ab');
},

The driver uses a hash table functions to store and retrieve data. Read more about the hash table functions here.

Choose a driver

After you have chosen a driver, you need to configure the dependency injection container:

di.php

use Xepozz\FeatureFlag\FlagStorageInterface;
use \Xepozz\FeatureFlag\Driver\RedisDriver;

return [
    // ...
    FlagStorageInterface::class => RedisDriver::class,
    // ...
]

Usage

Pull \Xepozz\FeatureFlag\FlagStorageInterface from the dependency injection container and use it:

isActive(string|int|BackedEnum $flag): bool

use Xepozz\FeatureFlag\FlagStorageInterface;

class Controller
{
    public function index(FlagStorageInterface $flagStorage)
    {
        if ($flagStorage->isActive('feature_name')) {
            // feature is enabled
        } else {
            // feature is disabled
        }
    }
}

setFlag(string|int|BackedEnum $flag, bool $active): void

Be careful, in case of using not the InMemoryDriver, the flag will be stored permanently.

In case of using the InMemoryDriver, the flag will be stored only for the current request. So you can switch the flag depending on the conditions in your code. For instance, you can enable the feature only for trusted IP addresses.

use Xepozz\FeatureFlag\FlagStorageInterface;

class Controller
{
    public function index(FlagStorageInterface $flagStorage)
    {
        if ($condition) {
            $flagStorage->setFlag('feature_name', true);
        }
    }
}

getAll(): array

Returns all flags as an associative array array<string, bool>.

The only InMemoryDriver supports returning BackendEnum as a key, because it does not need to serialize the key.

The key is the flag name, the value is the flag state.

use Xepozz\FeatureFlag\FlagStorageInterface;

class Controller
{
    public function index(FlagStorageInterface $flagStorage)
    {
        $flags = $flagStorage->getAll();
        // ...
    }
}

Testing

Redis

Redis driver requires phpredis extension and a running Redis server.

You can use the following command to start a Redis server in a Docker container:

docker run --rm -p 6379:6379 redis

Or use docker-compose:

docker-compose up -d

Run tests:

composer test

Or

./vendor/bin/phpunit

Looking for more modules?

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