FeatureFlagBundle

This bundle builds on Symfony's sophisticated security system and provides the means to assign features to roles. It helps you to:

Change your way of thinking: Do not define who can access some functionality, but what functionality is available.
Assign any feature (or role) to guests that are not logged in.
Make use of your existing Symfony knowledge: Access control works in the same way as in plain Symfony.

Installation

Install the bundle via Composer:

php composer.phar require matthimatiker/feature-flag-bundle

Enable the bundle in your kernel:

<?php
// app/AppKernel.php

public function registerBundles()
{
    $bundles = array(
        // ...
        new Matthimatiker\FeatureFlagBundle\MatthimatikerFeatureFlagBundle(),
        // ...
    );
    // ...
}

Usage

Configure Features

Features are assigned to roles. You connect features and roles in your security.yml via Symfony's well known hierarchical roles:

security:
    # ...
    
    role_hierarchy:
        # Start with a role and assign the accessible features.
        ROLE_USER:
            - FEATURE_BLOG
            
        # You can organize your features in groups and assign sub-features.
        # These are inherited just like roles.
        FEATURE_BLOG:
            - FEATURE_BLOG_WRITE
            - FEATURE_BLOG_READ
            
        # Features may depend on IS_AUTHENTICATED_* permissions.
        # That is useful to assign features to all visitors (logged in or not):
        IS_AUTHENTICATED_ANONYMOUSLY:
            - FEATURE_NEWSLETTER_REGISTRATION
            
        # The role ROLE_ANONYMOUS is used to assign features to visitors that are not logged in.
        ROLE_ANONYMOUS:
            - FEATURE_LOGIN

The security.yml is the central place to map features to roles. To distinguish features from roles, they are prefixed with FEATURE_*.

Grouping Features

Like normal roles in the hierarchy, features can be grouped. This allows you to compose new features from sub-features:

FEATURE_BLOG_USER:
    - FEATURE_BLOG_READ
    - FEATURE_BLOG_WRITE

FEATURE_BLOG_ADMIN:
    - FEATURE_BLOG_USER
    - FEATURE_BLOG_DELETE

In the example above, any user that has the permission FEATURE_BLOG_ADMIN will also inherit the permissions FEATURE_BLOG_WRITE, FEATURE_BLOG_WRITE and FEATURE_BLOG_DELETE. Composing features in this way guarantees fine-grained permission control. Want to prevent the deletion of blog posts? Just remove FEATURE_BLOG_DELETE from the hierarchy.

Features For All Users

In plain Symfony, you cannot assign roles to anonymous users. This bundle overcomes that limitation by allowing the assignment of roles and features to Symfony's IS_AUTHENTICATED_* permissions in the hierarchy.

Be aware that the existing rules for the IS_AUTHENTICATED_* permissions apply. For example IS_AUTHENTICATED_ANONYMOUSLY is available to all visitors, guests as well as logged in users. This means that any feature assigned to IS_AUTHENTICATED_ANONYMOUSLY will be available to everyone.

Features Only For Guests

With standard Symfony it is not possible to assign roles to users that are not logged in. This bundle removes that limitation by introducing the special role ROLE_ANONYMOUS. ROLE_ANONYMOUS is only assigned to anonymous users. Once a user logs in, she will lose that role.

ROLE_ANONYMOUS can be used in the role hierarchy configuration to assign features to guests:

ROLE_ANONYMOUS:
    - FEATURE_LOGIN

Managing guest features in the role hierarchy allows you to enable and disable these features via simple configuration change.

Access Control

Access should be checked against the features using the existing mechanisms in Symfony. Of course you can also still check access against roles, although it should not be necessary.

Controller Actions

You can check access to contoller actions in the same way as with roles:

/**
 * @Security("has_role('FEATURE_NEWSLETTER_REGISTRATION')")
 */
public function myAction($name)
{
    // ...
}

Twig Templates

Within your Twig templates, you can use the is_granted() function:

{% if is_granted('FEATURE_NEWSLETTER_REGISTRATION') %}
    <a href="...">Register now</a>
{% endif %}

Other Areas

You can check against features anywhere you used roles before, for example in the access_control section of your security.yml, together with Symfony's controller helper methods or directly with the security.authorization_checker service.

Known Issues and Limitations

This bundle deals with managing access to features via security configuration, so a permission change also requires a configuration change. It does not provide means to enable and disable features on the fly, although that should be possible via dynamic roles (just to mention one approach). However, on-the-fly feature management is currently out of scope for this bundle as it is a very application specific topic.

Matthimatiker/FeatureFlagBundle