Flagception Bundle for Symfony

When multiple parameters are provided for a feature, Flagception follows a specific evaluation chain to determine if a feature is active:

1. default: The default value is checked first.
2. env: If the default value is false, the value from the environment variable specified in env is checked.
3. constraint: If both default and env return false, the constraint logic is evaluated.

If any step in this chain results in a true status, the feature is considered active.

# config.yml

flagception:
    features:      
        feature_123:
            default: false
            env: FEATURE_NAME_FROM_ENV  
            constraint: 'user_role == ROLE_ADMIN'

Activators are responsible for resolving the state of a feature. When checking if a feature is active, the Feature Manager iterates through all registered activators and calls their isActive method.

The Short-Circuit Rule: The manager stops at the first activator that returns true. If an activator returns true, no further activators in the chain will be queried. If an activator returns false, the manager proceeds to the next one.

By default, the bundle includes a ConfigActivator which reads feature states from config.yml. You can implement custom activators to fetch feature states from external sources like remote servers or user roles.

// The manager iterates through activators until one returns true
if ($activator->isActive($featureName, $context)) {
    // Stop here, feature is active
}

The bundle includes a Symfony Profiler tab that allows you to inspect feature toggle behavior during a request. The profiler displays:

• How often a feature was requested.
• The result returned (active or inactive).
• The context provided during the evaluation.

By default, the cookie activator operates in whitelist mode, meaning only features defined in your config.yml can be enabled via cookies.

If you set mode: 'blacklist' in your cookie configuration, the behavior changes: every feature can be enabled via the cookie unless it has been explicitly disabled in the feature configuration using cookie: false. This allows you to activate features that are not even defined in your current config.yml via the cookie.

# config.yml

flagception:
    features:      
        feature_123:
            default: false
            
        feature_456:
            default: false
            cookie: false
   
    activators:
        cookie:
            enable: true
            mode: 'blacklist'

If you are not using Symfony autoconfiguration, you must manually register your activator in your service configuration (e.g., services.yml) using the flagception.activator tag. You can optionally specify a priority to determine its position in the execution chain.

flagception.activator.config_activator:
    class: Flagception\Bundle\FlagceptionBundle\Activator\ConfigActivator
    arguments:
        - '@flagception.constraint.constraint_resolver'
    tags:
        - { name: flagception.activator, priority: 100 }

Upgrading from version 2.x to 3.0 involves a complete rework of the bundle. The underlying engine has changed to the Flagception library.

Key breaking changes include:

• Package Name: The composer package has changed from bestit/feature-toggle-bundle to flagception/flagception-bundle.
• Namespaces: All namespaces and service IDs have been renamed to use the Flagception\ or Flagception\Bundle\FlagceptionBundle prefix.
• Events: All previous events have been removed.

The DatabaseActivator is not included in the core bundle by default. To manage feature toggles via a database, you must install it as a dependency using Composer.

$ composer require flagception/database-activator

To restrict access to a specific controller action based on a single feature flag, add the _feature key to the route's defaults. You can do this using PHP annotations, YAML configuration, or XML configuration.

/**
 * @Route("/blog/{page}", defaults={"_feature": "feature_123"})
 */
public function listAction($page)
{
    // ...
}

# app/config/routing.yml
blog_list:
    path:      /blog/{page}
    defaults:  { _controller: AppBundle:Blog:list, _feature: 'feature_789' }

<!-- app/config/routing.xml -->
<route id="blog_list" path="/blog/{page}">
    <default key="_controller">AppBundle:Blog:list</default>
    <default key="_feature">feature_123</default>
</route>

To require multiple feature flags to be active for a route to be accessible, pass an array of feature names to the _feature key in the route defaults. The route will only be accessible if all specified features are active.

/**
 * @Route("/blog/{page}", defaults={"_feature": {"feature_123", "feature_456"}})
 */
public function listAction($page)
{
    // ...
}

# app/config/routing.yml
blog_list:
    path:      /blog/{page}
    defaults:  { _controller: AppBundle:Blog:list, _feature: ['feature_456', 'feature_789'] }

<!-- app/config/routing.xml -->
<route id="blog_list" path="/blog/{page}">
    <default key="_controller">AppBundle:Blog:list</default>
    <default key="_feature">
        <list>
            <string>feature_123</string>
            <string>feature_456</string>
        </list>
    </default>
</route>