Example how to override configuration from custom module in Drupal 8

In this tuto, I'll show you how to override configuration from custom module in Drupal 8.

• Create a module (codimth_config_override used as an example)

name: Config Override Example
description: Provide a config override from custom module
package: CodimTh
type: module
core: 8.x

• Create a codimth_config_override.services.yml, and put:

services:
  codimth_config_override.overrider:
    class: Drupal\codimth_config_override\Config\ConfigExampleOverrides
    tags:
      - {name: config.factory.override, priority: 5}

config.factory.override is the important thing here, others are up to you to change.

• Define the class which implements ConfigFactoryOverrideInterface:

<?php
namespace Drupal\codimth_config_override\Config;

use Drupal\Core\Cache\CacheableMetadata;
use Drupal\Core\Config\ConfigFactoryOverrideInterface;
use Drupal\Core\Config\StorageInterface;

/**
 * Example configuration override.
 */
class ConfigExampleOverrides implements ConfigFactoryOverrideInterface {

    /**
     * {@inheritdoc}
     */
    public function loadOverrides($names) {
        $overrides = array();
        if (in_array('system.site', $names)) {
            $overrides['system.site'] = ['name' => 'My site name!'];
        }
        return $overrides;
    }

    /**
     * {@inheritdoc}
     */
    public function getCacheSuffix() {
        return 'ConfigExampleOverrider';
    }

    /**
     * {@inheritdoc}
     */
    public function getCacheableMetadata($name) {
        return new CacheableMetadata();
    }

    /**
     * {@inheritdoc}
     */
    public function createConfigObject($name, $collection = StorageInterface::DEFAULT_COLLECTION) {
        return NULL;
    }

}

"system.site" which is the YML you wish to override. The value assigned to $overrides['system.site'] is changed to what you wish to be placed.

to get the original value juste use:

$name = \Drupal::config('system.site')->getOriginal('name', FALSE);

Next steps

• Clear your Drupal 8 caches. To do this I use this Drush command: drush cr if you don’t currently use Drush, I highly recommend using it, or the Drupal Console.
• Now, enable the module, and you should be able to see if your site name is overriden or not yet.
• I hope you found this article useful. let me know if you have any questions and I’ll be happy to answer them.
• This code can be found and downloaded from https://github.com/codimth/codimth_config_override.