Feature Switches

This library provides the most basic implementation of so called feature switches(aka feature toggles/feature flags).

Setup:

Install the library

composer require dorumd/feature-switches

Configure your feature switches(example):

# config/feature-switches.yaml
feature_switches:
  SEND_ORDER_EMAILS:
     enabled: true
  SEND_MERCHANT_NOTIFICATIONS:
     enabled: false

Basic usage:

<?php
// index.php

use Dorumd\FeatureSwitches\Domain\BasicFeatureSwitches;
use Dorumd\FeatureSwitches\Infrastructure\FileFeatureSwitchesStorage;

$configPath = __DIR__ . '/config/feature-switches.yaml';
$featureSwitchesStorage = new FileFeatureSwitchesStorage($configPath);

$featureSwitches = new BasicFeatureSwitches($featureSwitchesStorage);

echo $featureSwitches->featureIsEnabled('SEND_MERCHANT_NOTIFICATIONS');
echo $featureSwitches->featureIsEnabled('SEND_ORDER_EMAILS');

Supported feature switches:

• Basic(default type)

  Basic feature switch solely relies on enabled flag. Configuration reference:

  feature_switches:
    # By default, it will set type to basic:
    SEND_ORDER_EMAILS:
       enabled: true
    # Explicit configuration:
    SEND_NOTIFICATIONS:
       enabled: true
       type: \Dorumd\FeatureSwitches\Domain\BasicFeatureSwitch 

• Percentage split

  Percentage split feature switch can be used for the gradual rollout, or A/B tests. Configuration reference:

  feature_switches:
    SPLIT_TEST_1:
      enabled: true
      type: \Dorumd\FeatureSwitches\Domain\PercentageSplitFeatureSwitch
      configuration:
        percentage: 50 

  Note: The accuracy of its percentage split is limited by randomness of php rand(1, 100). With smaller samples(N < 1000), higher deviation is expected.

• More to come soon...

Storage

This library comes with 3 storage mechanisms embedded:

• file(yaml format)

  // config/feature_switches.yaml
  feature_switches:
    SEND_ORDER_EMAILS:
      enabled: true

  <?php
  // index.php
  use Dorumd\FeatureSwitches\Domain\BasicFeatureSwitches;
  use Dorumd\FeatureSwitches\Infrastructure\FileFeatureSwitchesStorage;
  
  $configPath = __DIR__ . '/config/feature-switches.yaml';
  $featureSwitchesStorage = new FileFeatureSwitchesStorage($configPath);
  
  $featureSwitches = new BasicFeatureSwitches($featureSwitchesStorage);
  echo $featureSwitches->featureIsEnabled('SEND_ORDER_EMAILS');

• in memory

  <?php
  // index.php
  use Dorumd\FeatureSwitches\Domain\BasicFeatureSwitches;
  use Dorumd\FeatureSwitches\Domain\BasicFeatureSwitch;
  use Dorumd\FeatureSwitches\Domain\PercentageSplitFeatureSwitch;
  use Dorumd\FeatureSwitches\Infrastructure\InMemoryFeatureSwitchesStorage;
  
  $featureSwitchesStorage = new InMemoryFeatureSwitchesStorage();
  $featureSwitchesStorage->store(new BasicFeatureSwitch('SEND_ORDER_EMAILS', false));
  $featureSwitchesStorage->store(new BasicFeatureSwitch('SEND_NOTIFICATION', true));
  $featureSwitchesStorage->store(
      new PercentageSplitFeatureSwitch('DISPLAY_SURVEY', true, ['percentage' => 50])
  );
  
  $featureSwitches = new BasicFeatureSwitches($featureSwitchesStorage);
  echo $featureSwitches->featureIsEnabled('SEND_ORDER_EMAILS');
  echo $featureSwitches->featureIsEnabled('DISPLAY_SURVEY');

• composite: use case - file storage for defaults and database storage in admin which overrides it

  // config/feature_switches.yaml
  feature_switches:
    SEND_ORDER_EMAILS:
      enabled: true

  <?php
  // index.php
  use Dorumd\FeatureSwitches\Domain\BasicFeatureSwitches;
  use Dorumd\FeatureSwitches\Domain\BasicFeatureSwitch;
  use Dorumd\FeatureSwitches\Domain\PercentageSplitFeatureSwitch;
  use Dorumd\FeatureSwitches\Infrastructure\FileFeatureSwitchesStorage;
  use Dorumd\FeatureSwitches\Infrastructure\CompositeStorage;
  use Dorumd\FeatureSwitches\Infrastructure\InMemoryFeatureSwitchesStorage;
  
  $configPath = __DIR__ . '/config/feature-switches.yaml';
  $fileFeatureSwitchesStorage = new FileFeatureSwitchesStorage($configPath);
  
  $featureSwitchesStorage = new InMemoryFeatureSwitchesStorage();
  $featureSwitchesStorage->store(new BasicFeatureSwitch('SEND_ORDER_EMAILS', false));
  $featureSwitchesStorage->store(new BasicFeatureSwitch('SEND_NOTIFICATION', true));
  $featureSwitchesStorage->store(
      new PercentageSplitFeatureSwitch('DISPLAY_SURVEY', true, ['percentage' => 50])
  );
  
  $featureSwitches = new BasicFeatureSwitches(
      // ordered ASC, last one overrides first one.
      new CompositeStorage([$fileFeatureSwitchesStorage, $featureSwitchesStorage])
  );
  echo $featureSwitches->featureIsEnabled('SEND_ORDER_EMAILS'); // false, in memory storage is overriding file.
  echo $featureSwitches->featureIsEnabled('DISPLAY_SURVEY');

Development:

Dependencies: Docker

# Build the docker image with all deps., run tests and validate code format
make build

To fix code formatting errors:

make fix-code-format