Issue #3047812 by bircher, Krzysztof Domański, alexpott, ricardoamaro,...

Issue #3047812 by bircher, Krzysztof Domański, alexpott, ricardoamaro, larowlan, borisson_, mpotter: Add a Config Transformation event dispatching during config import and export

core/modules/config_environment/config_environment.module

@@ -5,6 +5,15 @@
  * Allows site administrators to modify environment configuration.
  */
 
+// Set class aliases for the classes that will go into core when we are in beta.
+// See the experimental modules policy https://www.drupal.org/core/experimental
+// @todo: remove class aliases in #2991683
+@class_alias('Drupal\config_environment\Core\Config\StorageTransformEvent', 'Drupal\Core\Config\StorageTransformEvent');
+@class_alias('Drupal\config_environment\Core\Config\ManagedStorage', 'Drupal\Core\Config\ManagedStorage');
+@class_alias('Drupal\config_environment\Core\Config\StorageManagerInterface', 'Drupal\Core\Config\StorageManagerInterface');
+@class_alias('Drupal\config_environment\Core\Config\ExportStorageManager', 'Drupal\Core\Config\ExportStorageManager');
+@class_alias('Drupal\config_environment\Core\Config\ImportStorageTransformer', 'Drupal\Core\Config\ImportStorageTransformer');
+
 use Drupal\Core\Routing\RouteMatchInterface;
 
 /**

core/modules/config_environment/config_environment.routing.yml

+# @todo: Stop taking over config module routes in #2991683
+config.sync:
+  path: '/admin/config/development/configuration'
+  defaults:
+    _form: '\Drupal\config_environment\Form\ConfigSync'
+    _title: 'Synchronize'
+  requirements:
+    _permission: 'synchronize configuration'
+
+config.diff:
+  path: '/admin/config/development/configuration/sync/diff/{source_name}/{target_name}'
+  defaults:
+    _controller: '\Drupal\config_environment\Controller\ConfigController::diff'
+    target_name: NULL
+  requirements:
+    _permission: 'synchronize configuration'
+
+config.diff_collection:
+  path: '/admin/config/development/configuration/sync/diff_collection/{collection}/{source_name}/{target_name}'
+  defaults:
+    _controller: '\Drupal\config_environment\Controller\ConfigController::diff'
+    target_name: NULL
+  requirements:
+    _permission: 'synchronize configuration'
+
+config.export_download:
+  path: '/admin/config/development/configuration/full/export-download'
+  defaults:
+    _controller: '\Drupal\config_environment\Controller\ConfigController::downloadExport'
+  requirements:
+    _permission: 'export configuration'

core/modules/config_environment/config_environment.services.yml

+services:
+  # @todo: Move this back to core services in #2991683
+  config.import_transformer:
+    class: Drupal\config_environment\Core\Config\ImportStorageTransformer
+    arguments: ['@event_dispatcher', '@database']
+  config.storage.export:
+    class: Drupal\config_environment\Core\Config\ManagedStorage
+    arguments: ['@config.storage.export.manager']
+  config.storage.export.manager:
+    class: Drupal\config_environment\Core\Config\ExportStorageManager
+    arguments: ['@config.storage', '@state', '@database', '@event_dispatcher']
+    tags:
+      - { name: event_subscriber }

core/modules/config_environment/src/Controller/ConfigController.php

+<?php
+
+namespace Drupal\config_environment\Controller;
+
+use Drupal\config\Controller\ConfigController as OriginalConfigController;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Returns responses for config module routes.
+ */
+class ConfigController extends OriginalConfigController {
+
+  /**
+   * The import transformer service.
+   *
+   * @var \Drupal\Core\Config\ImportStorageTransformer
+   */
+  protected $importTransformer;
+
+  /**
+   * The sync storage.
+   *
+   * @var \Drupal\Core\Config\StorageInterface
+   */
+  protected $syncStorage;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    $controller = parent::create($container);
+    $controller->importTransformer = $container->get('config.import_transformer');
+    $controller->syncStorage = $container->get('config.storage.sync');
+
+    return $controller;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function diff($source_name, $target_name = NULL, $collection = NULL) {
+    $this->sourceStorage = $this->importTransformer->transform($this->syncStorage);
+
+    return parent::diff($source_name, $target_name, $collection);
+  }
+
+}

core/modules/config_environment/src/Core/Config/ConfigEvents.php

+<?php
+
+// @codingStandardsIgnoreStart
+// @todo: Move this back to \Drupal\Core\Config\ConfigEvents in #2991683.
+// @codingStandardsIgnoreEnd
+namespace Drupal\config_environment\Core\Config;
+
+/**
+ * Defines events for the configuration transform system.
+ *
+ * The constants in this class will be moved back into ConfigEvents.
+ * But due to the fact that the config_environment is not in beta we save their
+ * definitions here and use the literal strings in the mean time.
+ *
+ * @internal
+ *
+ * @deprecated The class will be merged with Drupal\Core\Config\ConfigEvents.
+ */
+final class ConfigEvents {
+
+  /**
+   * Name of the event fired just before importing configuration.
+   *
+   * This event allows subscribers to modify the configuration which is about to
+   * be imported. The event listener method receives a
+   * \Drupal\Core\Config\StorageTransformEvent instance. This event contains a
+   * config storage which subscribers can interact with and which will finally
+   * be used to import the configuration from.
+   * Together with \Drupal\Core\Config\ConfigEvents::STORAGE_TRANSFORM_EXPORT
+   * subscribers can alter the active configuration in a config sync workflow
+   * instead of just overriding at runtime via the config-override system.
+   * This allows a complete customisation of the workflow including additional
+   * modules and editable configuration in different environments.
+   *
+   * @code
+   *   $storage = $event->getStorage();
+   * @endcode
+   *
+   * This event is also fired when just viewing the difference of configuration
+   * to be imported independently of whether the import takes place or not.
+   * Use the \Drupal\Core\Config\ConfigEvents::IMPORT event to subscribe to the
+   * import having taken place.
+   *
+   * @Event
+   *
+   * @see \Drupal\Core\Config\StorageTransformEvent
+   * @see \Drupal\Core\Config\ConfigEvents::STORAGE_TRANSFORM_EXPORT
+   *
+   * @var string
+   */
+  const STORAGE_TRANSFORM_IMPORT = 'config.transform.import';
+
+  /**
+   * Name of the event fired when the export storage is used.
+   *
+   * This event allows subscribers to modify the configuration which is about to
+   * be exported. The event listener method receives a
+   * \Drupal\Core\Config\StorageTransformEvent instance. This event contains a
+   * config storage which subscribers can interact with and which will finally
+   * be used to export the configuration from.
+   *
+   * @code
+   *   $storage = $event->getStorage();
+   * @endcode
+   *
+   * Typically subscribers will want to perform the reverse operation on the
+   * storage than for \Drupal\Core\Config\ConfigEvents::STORAGE_TRANSFORM_IMPORT
+   * to make sure successive exports and imports yield no difference.
+   *
+   * @Event
+   *
+   * @see \Drupal\Core\Config\StorageTransformEvent
+   * @see \Drupal\Core\Config\ConfigEvents::STORAGE_TRANSFORM_IMPORT
+   *
+   * @var string
+   */
+  const STORAGE_TRANSFORM_EXPORT = 'config.transform.export';
+
+}

core/modules/config_environment/src/Core/Config/ExportStorageManager.php

+<?php
+
+// @codingStandardsIgnoreStart
+// @todo: Move this back to \Drupal\Core\Config in #2991683.
+// Use this class with its class alias Drupal\Core\Config\ExportStorageManager
+// @codingStandardsIgnoreEnd
+namespace Drupal\config_environment\Core\Config;
+
+use Drupal\Core\Config\ConfigEvents;
+use Drupal\Core\Config\DatabaseStorage;
+use Drupal\Core\Config\ReadOnlyStorage;
+use Drupal\Core\Config\StorageCopyTrait;
+use Drupal\Core\Config\StorageInterface;
+use Drupal\Core\Database\Connection;
+use Drupal\Core\State\StateInterface;
+use Symfony\Component\EventDispatcher\EventDispatcherInterface;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * The export storage manager dispatches an event for the export storage.
+ *
+ * @internal
+ */
+class ExportStorageManager implements StorageManagerInterface, EventSubscriberInterface {
+
+  use StorageCopyTrait;
+
+  /**
+   * The state key indicating that the export storage needs to be rebuilt.
+   */
+  const NEEDS_REBUILD_KEY = 'config_export_needs_rebuild';
+
+  /**
+   * The active configuration storage.
+   *
+   * @var \Drupal\Core\Config\StorageInterface
+   */
+  protected $active;
+
+  /**
+   * The drupal state.
+   *
+   * @var \Drupal\Core\State\StateInterface
+   */
+  protected $state;
+
+  /**
+   * The database storage.
+   *
+   * @var \Drupal\Core\Config\DatabaseStorage
+   */
+  protected $storage;
+
+  /**
+   * The event dispatcher.
+   *
+   * @var \Symfony\Component\EventDispatcher\EventDispatcherInterface
+   */
+  protected $eventDispatcher;
+
+  /**
+   * ExportStorageManager constructor.
+   *
+   * @param \Drupal\Core\Config\StorageInterface $active
+   *   The active config storage to prime the export storage.
+   * @param \Drupal\Core\State\StateInterface $state
+   *   The drupal state.
+   * @param \Drupal\Core\Database\Connection $connection
+   *   The database connection.
+   * @param \Symfony\Component\EventDispatcher\EventDispatcherInterface $event_dispatcher
+   *   The event dispatcher.
+   */
+  public function __construct(StorageInterface $active, StateInterface $state, Connection $connection, EventDispatcherInterface $event_dispatcher) {
+    $this->active = $active;
+    $this->state = $state;
+    $this->eventDispatcher = $event_dispatcher;
+    // The point of this service is to provide the storage and dispatch the
+    // event when needed, so the storage itself can not be a service.
+    $this->storage = new DatabaseStorage($connection, 'config_export');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getStorage() {
+    if ($this->state->get(self::NEEDS_REBUILD_KEY, TRUE)) {
+      self::replaceStorageContents($this->active, $this->storage);
+      // @todo: Use ConfigEvents::STORAGE_TRANSFORM_EXPORT in #2991683
+      $this->eventDispatcher->dispatch('config.transform.export', new StorageTransformEvent($this->storage));
+      $this->state->set(self::NEEDS_REBUILD_KEY, FALSE);
+    }
+
+    return new ReadOnlyStorage($this->storage);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents() {
+    $events[ConfigEvents::SAVE][] = ['onConfigChange', 0];
+    $events[ConfigEvents::DELETE][] = ['onConfigChange', 0];
+    $events[ConfigEvents::RENAME][] = ['onConfigChange', 0];
+    return $events;
+  }
+
+  /**
+   * Set the flag in state that the export storage is out of date.
+   */
+  public function onConfigChange() {
+    if (!$this->state->get(self::NEEDS_REBUILD_KEY, FALSE)) {
+      $this->state->set(self::NEEDS_REBUILD_KEY, TRUE);
+    }
+  }
+
+}

core/modules/config_environment/src/Core/Config/ImportStorageTransformer.php

+<?php
+
+// @codingStandardsIgnoreStart
+// @todo: Move this back to \Drupal\Core\Config in #2991683.
+// Use this class with its class alias Drupal\Core\Config\ImportStorageTransformer
+// @codingStandardsIgnoreEnd
+namespace Drupal\config_environment\Core\Config;
+
+use Drupal\Core\Database\Connection;
+use Symfony\Component\EventDispatcher\EventDispatcherInterface;
+use Drupal\Core\Config\DatabaseStorage;
+use Drupal\Core\Config\StorageCopyTrait;
+use Drupal\Core\Config\StorageInterface;
+
+/**
+ * Class ImportStorageTransformer.
+ *
+ * @internal
+ */
+class ImportStorageTransformer {
+
+  use StorageCopyTrait;
+
+  /**
+   * The event dispatcher to get changes to the configuration.
+   *
+   * @var \Symfony\Component\EventDispatcher\EventDispatcherInterface
+   */
+  protected $eventDispatcher;
+
+  /**
+   * The drupal database connection.
+   *
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $connection;
+
+  /**
+   * ImportStorageTransformer constructor.
+   *
+   * @param \Symfony\Component\EventDispatcher\EventDispatcherInterface $event_dispatcher
+   *   The event dispatcher.
+   * @param \Drupal\Core\Database\Connection $connection
+   *   The database connection.
+   */
+  public function __construct(EventDispatcherInterface $event_dispatcher, Connection $connection) {
+    $this->eventDispatcher = $event_dispatcher;
+    $this->connection = $connection;
+  }
+
+  /**
+   * Transform the storage to be imported from.
+   *
+   * An import transformation is done before the config importer uses the
+   * storage to synchronize the configuration. The transformation is also
+   * done for displaying differences to review imports.
+   * Importing in this context means the active drupal configuration is changed
+   * with the ConfigImporter which may or may not be as part of the config
+   * synchronization.
+   *
+   * @param \Drupal\Core\Config\StorageInterface $storage
+   *   The storage to transform for importing from it.
+   *
+   * @return \Drupal\Core\Config\StorageInterface
+   *   The transformed storage ready to be imported from.
+   */
+  public function transform(StorageInterface $storage) {
+    // We use a database storage to reduce the memory requirement.
+    $mutable = new DatabaseStorage($this->connection, 'config_import');
+
+    // Copy the sync configuration to the created mutable storage.
+    self::replaceStorageContents($storage, $mutable);
+
+    // Dispatch the event so that event listeners can alter the configuration.
+    // @todo: Use ConfigEvents::STORAGE_TRANSFORM_IMPORT in #2991683
+    $this->eventDispatcher->dispatch('config.transform.import', new StorageTransformEvent($mutable));
+
+    // Return the storage with the altered configuration.
+    return $mutable;
+  }
+
+}

core/modules/config_environment/src/Core/Config/ManagedStorage.php

+<?php
+
+// @codingStandardsIgnoreStart
+// @todo: Move this back to \Drupal\Core\Config in #2991683.
+// Use this class with its class alias Drupal\Core\Config\ManagedStorage
+// @codingStandardsIgnoreEnd
+namespace Drupal\config_environment\Core\Config;
+
+use Drupal\Core\Config\StorageInterface;
+
+/**
+ * The managed storage defers all the storage method calls to the manager.
+ *
+ * The reason for deferring all the method calls is that the storage interface
+ * is the API but we potentially need to do an expensive transformation before
+ * the storage can be used so we can't do it in the constructor but we also
+ * don't know which method is called first.
+ *
+ * @internal
+ */
+class ManagedStorage implements StorageInterface {
+
+  /**
+   * The decorated storage.
+   *
+   * @var \Drupal\Core\Config\StorageInterface
+   */
+  protected $storage;
+
+  /**
+   * The storage manager to get the storage to decorate.
+   *
+   * @var \Drupal\Core\Config\StorageManagerInterface
+   */
+  protected $manager;
+
+  /**
+   * ManagedStorage constructor.
+   *
+   * @param \Drupal\Core\Config\StorageManagerInterface $manager
+   *   The storage manager.
+   */
+  public function __construct(StorageManagerInterface $manager) {
+    $this->manager = $manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function exists($name) {
+    return $this->getStorage()->exists($name);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function read($name) {
+    return $this->getStorage()->read($name);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function readMultiple(array $names) {
+    return $this->getStorage()->readMultiple($names);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function write($name, array $data) {
+    return $this->getStorage()->write($name, $data);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function delete($name) {
+    return $this->getStorage()->delete($name);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function rename($name, $new_name) {
+    return $this->getStorage()->rename($name, $new_name);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function encode($data) {
+    return $this->getStorage()->encode($data);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function decode($raw) {
+    return $this->getStorage()->decode($raw);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function listAll($prefix = '') {
+    return $this->getStorage()->listAll($prefix);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function deleteAll($prefix = '') {
+    return $this->getStorage()->deleteAll($prefix);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function createCollection($collection) {
+    // We return the collection directly.
+    // This means that the collection will not be an instance of ManagedStorage
+    // But this doesn't matter because the storage is retrieved from the
+    // manager only the first time it is accessed.
+    return $this->getStorage()->createCollection($collection);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getAllCollectionNames() {
+    return $this->getStorage()->getAllCollectionNames();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCollectionName() {
+    return $this->getStorage()->getCollectionName();
+  }
+
+  /**
+   * Get the decorated storage from the manager if necessary.
+   *
+   * @return \Drupal\Core\Config\StorageInterface
+   *   The config storage.
+   */
+  protected function getStorage() {
+    // Get the storage from the manager the first time it is needed.
+    if (!isset($this->storage)) {
+      $this->storage = $this->manager->getStorage();
+    }
+
+    return $this->storage;
+  }
+
+}

core/modules/config_environment/src/Core/Config/StorageManagerInterface.php

+<?php
+
+// @codingStandardsIgnoreStart
+// @todo: Move this back to \Drupal\Core\Config in #2991683.
+// Use this class with its class alias Drupal\Core\Config\StorageManagerInterface
+// @codingStandardsIgnoreEnd
+namespace Drupal\config_environment\Core\Config;
+
+/**
+ * Interface for a storage manager.
+ *
+ * @internal
+ */
+interface StorageManagerInterface {
+
+  /**
+   * Get the config storage.
+   *
+   * @return \Drupal\Core\Config\StorageInterface
+   *   The config storage.
+   */
+  public function getStorage();
+
+}

core/modules/config_environment/src/Core/Config/StorageTransformEvent.php

+<?php
+
+// @codingStandardsIgnoreStart
+// @todo: Move this back to \Drupal\Core\Config in #2991683.
+// Use this class with its class alias Drupal\Core\Config\StorageTransformEvent
+// @codingStandardsIgnoreEnd
+namespace Drupal\config_environment\Core\Config;
+
+use Symfony\Component\EventDispatcher\Event;
+// @todo: below removed when namespace is \Drupal\Core\Config in 2991683.
+use Drupal\Core\Config\StorageInterface;
+
+/**
+ * Class StorageTransformEvent.
+ *
+ * This event allows subscribers to alter the configuration of the storage that
+ * is being transformed.
+ */
+class StorageTransformEvent extends Event {
+
+  /**
+   * The configuration storage which is transformed.
+   *