README

This bundle adds feature toggle functionality to your Symfony project.

Requirements

In order to install ECNFeatureToggleBundle, you need at least

• PHP 8.0 or greater
• Symfony 5.4 or greater

Installation

Step 1: Install via composer

$ composer require ecn/featuretoggle-bundle

Functionality of twig is only optional. Require it to your composer if you need it to use it.

$ composer require twig/twig

Step 2: Activate the bundle

Add the bundle to the AppKernel.php:

<?php

// in AppKernel::registerBundles()
$bundles = array(
    // ...
    new Ecn\FeatureToggleBundle\EcnFeatureToggleBundle(),
    // ...
);

Configuration

The idea behind Feature Toggle development is that features are defined on a local basis. Because of this it is a good idea to have your feature definitions in a separate config file, which shouldn't be under version control:

Create a new yml file, e.g. features.yml and make your SCM ignore this file.

Then add the following configuration to your features.yml:

ecn_feature_toggle:
    features:

Import the features.yml file into your configuration:

imports:
    - { resource: features.yml, ignore_errors: true }

Usage

Step 1: Add a feature toggle

Define a new feature toggle inside your feature configuration:

ecn_feature_toggle:
    features:
        MyNewFeature:

Step 2: Check for a feature toggle inside the code

Now you can check inside your code, if this feature is defined.

Inside a twig template:

{% if feature('MyNewFeature') %}
    <p>Here is my new feature!</p>
{% endif %}

Or using the tag:

{% feature MyNewFeature %}
    <p>Here is my new feature!</p>
{% endfeature %}

Inside an action:

if ($this->get('feature')->has('MyNewFeature')) {
    // Your new feature here
}

Voters

In order to decide if a feature is available or not, voters are being used. Currently, there are five voters included.

AlwaysTrueVoter

This is the default voter, and it will always pass. So if you have a feature defined, it will always be displayed.

The full configuration for using this voter looks like this:

ecn_feature_toggle:
    features:
        MyNewFeature:
            voter: AlwaysTrueVoter

Because this is the default voter, the voter part in the configuration can be omitted.

AlwaysFalseVoter

This voter will always fail. If you have a feature defined that uses this voter, it will never be displayed.

The full configuration for using this voter looks like this:

ecn_feature_toggle:
    features:
        MyNewFeature:
            voter: AlwaysFalseVoter

RatioVoter

This voter passes on a given ratio between 0 and 1, which makes it suitable for A/B testing. The default ratio is 0.5.

The higher the ratio, the more likely the voter will pass. A value of 1 will make it pass every time, 0 will make it never pass.

Additionally, the result of the first check can be bound to the users' session. This is useful if you need a feature to be persistent across multiple requests. To enable this, just set sticky to true.

If you want to use this voter, this is the full configuration:

ecn_feature_toggle:
    features:
        MyNewFeature:
            voter: RatioVoter
            params: { ratio: 0.5, sticky: false }

ScheduleVoter

This voter passes on a given schedule being after now.

If you want to use this voter, this is the full configuration:

ecn_feature_toggle:
    features:
        MyNewFeature:
            voter: ScheduleVoter
            params: { schedule: '2015-10-23' }

RequestHeaderVoter

The name of the request header itself is by design case-insensitive.

Request header values are always treated as strings, so equal (==) checks are used and not identical matching (===).

Request header keys are by design case-insensitive.

The Voter does not pass if the request stack contains no current requests.

a. Specify key/value pairs

This voter passes, when all of the specified headers and their corresponding values are found and equal to that of the current request headers.

Example for key/value config:

ecn_feature_toggle:
    features:
        FooRequestFeature:
            voter: RequestHeaderVoter
            params: { headers: { foo: bar, x-cdn: 'akamai', x-location: 'cn' } }

b. specify request header keys only

You can also specify a list of request header keys without values.

In this case, only the existence of all of the specified request headers is checked.

All request header names are by the standard case-insensitive.

Example:

ecn_feature_toggle:
    features:
        FooRequestFeature:
            voter: RequestHeaderVoter
            params: { headers: { x-mobile, x-foo-debug-header } }

Mixing the two configurations is discouraged as it will lead to unexpected results by treating the config as key/value pairs, and will most likely cause the Voter to not pass.

Overriding the default voter

You can override the default voter like this:

ecn_feature_toggle:
    default:
        voter: RatioVoter
        params: { ratio: 0.1, sticky: true }

Adding your own voters

Adding voters is straight forward. First make sure, that your voter implements \Ecn\FeatureToggleBundle\Voters\VoterInterface.

Then define your voter as service, tag it as ecn_featuretoggle.voter and give it an alias:

<!-- Example Voter -->
<service id="ecn_featuretoggle.voter_example" class="My\Example\Voter">
    <tag name="ecn_featuretoggle.voter" alias="ExampleVoter" />
</service>

Testing

$ composer test

License

The MIT License (MIT). Please see License File for more information.