class DrupalKernel in Drupal 8

Same name and namespace in other branches

9 core/lib/Drupal/Core/DrupalKernel.php \Drupal\Core\DrupalKernel

The DrupalKernel class is the core of Drupal itself.

This class is responsible for building the Dependency Injection Container and also deals with the registration of service providers. It allows registered service providers to add their services to the container. Core provides the CoreServiceProvider, which, in addition to registering any core services that cannot be registered in the core.services.yaml file, adds any compiler passes needed by core, e.g. for processing tagged services. Each module can add its own service provider, i.e. a class implementing Drupal\Core\DependencyInjection\ServiceProvider, to register services to the container, or modify existing services.

Hierarchy

class \Drupal\Core\DrupalKernel implements \Symfony\Component\HttpKernel\TerminableInterface, DrupalKernelInterface uses InstallerRedirectTrait

Expanded class hierarchy of DrupalKernel

40 files declare their use of DrupalKernel

authorize.php in core/authorize.php: Administrative script for running authorized file operations.
db-tools.php in core/scripts/db-tools.php: A command line application to import a database generation script.
DiscoverServiceProvidersTest.php in core/tests/Drupal/Tests/Core/DrupalKernel/DiscoverServiceProvidersTest.php
DistributionProfileExistingSettingsTest.php in core/tests/Drupal/FunctionalTests/Installer/DistributionProfileExistingSettingsTest.php
DrupalKernelTest.php in core/tests/Drupal/Tests/Core/DrupalKernel/DrupalKernelTest.php

... See full list

File

core/lib/Drupal/Core/DrupalKernel.php, line 57

Namespace

Drupal\Core

View source

class DrupalKernel implements DrupalKernelInterface, TerminableInterface {
  use InstallerRedirectTrait;

  /**
   * Holds the class used for dumping the container to a PHP array.
   *
   * In combination with swapping the container class this is useful to e.g.
   * dump to the human-readable PHP array format to debug the container
   * definition in an easier way.
   *
   * @var string
   */
  protected $phpArrayDumperClass = '\\Drupal\\Component\\DependencyInjection\\Dumper\\OptimizedPhpArrayDumper';

  /**
   * Holds the default bootstrap container definition.
   *
   * @var array
   */
  protected $defaultBootstrapContainerDefinition = [
    'parameters' => [],
    'services' => [
      'database' => [
        'class' => 'Drupal\\Core\\Database\\Connection',
        'factory' => 'Drupal\\Core\\Database\\Database::getConnection',
        'arguments' => [
          'default',
        ],
      ],
      'cache.container' => [
        'class' => 'Drupal\\Core\\Cache\\DatabaseBackend',
        'arguments' => [
          '@database',
          '@cache_tags_provider.container',
          'container',
          DatabaseBackend::MAXIMUM_NONE,
        ],
      ],
      'cache_tags_provider.container' => [
        'class' => 'Drupal\\Core\\Cache\\DatabaseCacheTagsChecksum',
        'arguments' => [
          '@database',
        ],
      ],
    ],
  ];

  /**
   * Holds the class used for instantiating the bootstrap container.
   *
   * @var string
   */
  protected $bootstrapContainerClass = '\\Drupal\\Component\\DependencyInjection\\PhpArrayContainer';

  /**
   * Holds the bootstrap container.
   *
   * @var \Symfony\Component\DependencyInjection\ContainerInterface
   */
  protected $bootstrapContainer;

  /**
   * Holds the container instance.
   *
   * @var \Symfony\Component\DependencyInjection\ContainerInterface
   */
  protected $container;

  /**
   * The environment, e.g. 'testing', 'install'.
   *
   * @var string
   */
  protected $environment;

  /**
   * Whether the kernel has been booted.
   *
   * @var bool
   */
  protected $booted = FALSE;

  /**
   * Whether essential services have been set up properly by preHandle().
   *
   * @var bool
   */
  protected $prepared = FALSE;

  /**
   * Holds the list of enabled modules.
   *
   * @var array
   *   An associative array whose keys are module names and whose values are
   *   ignored.
   */
  protected $moduleList;

  /**
   * List of available modules and installation profiles.
   *
   * @var \Drupal\Core\Extension\Extension[]
   */
  protected $moduleData = [];

  /**
   * The class loader object.
   *
   * @var \Composer\Autoload\ClassLoader
   */
  protected $classLoader;

  /**
   * Config storage object used for reading enabled modules configuration.
   *
   * @var \Drupal\Core\Config\StorageInterface
   */
  protected $configStorage;

  /**
   * Whether the container can be dumped.
   *
   * @var bool
   */
  protected $allowDumping;

  /**
   * Whether the container needs to be rebuilt the next time it is initialized.
   *
   * @var bool
   */
  protected $containerNeedsRebuild = FALSE;

  /**
   * Whether the container needs to be dumped once booting is complete.
   *
   * @var bool
   */
  protected $containerNeedsDumping;

  /**
   * List of discovered services.yml pathnames.
   *
   * This is a nested array whose top-level keys are 'app' and 'site', denoting
   * the origin of a service provider. Site-specific providers have to be
   * collected separately, because they need to be processed last, so as to be
   * able to override services from application service providers.
   *
   * @var array
   */
  protected $serviceYamls;

  /**
   * List of discovered service provider class names or objects.
   *
   * This is a nested array whose top-level keys are 'app' and 'site', denoting
   * the origin of a service provider. Site-specific providers have to be
   * collected separately, because they need to be processed last, so as to be
   * able to override services from application service providers.
   *
   * Allowing objects is for example used to allow
   * \Drupal\KernelTests\KernelTestBase to register itself as service provider.
   *
   * @var array
   */
  protected $serviceProviderClasses;

  /**
   * List of instantiated service provider classes.
   *
   * @see \Drupal\Core\DrupalKernel::$serviceProviderClasses
   *
   * @var array
   */
  protected $serviceProviders;

  /**
   * Whether the PHP environment has been initialized.
   *
   * This legacy phase can only be booted once because it sets session INI
   * settings. If a session has already been started, re-generating these
   * settings would break the session.
   *
   * @var bool
   */
  protected static $isEnvironmentInitialized = FALSE;

  /**
   * The site directory.
   *
   * @var string
   */
  protected $sitePath;

  /**
   * The app root.
   *
   * @var string
   */
  protected $root;

  /**
   * Create a DrupalKernel object from a request.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The request.
   * @param $class_loader
   *   The class loader. Normally Composer's ClassLoader, as included by the
   *   front controller, but may also be decorated; e.g.,
   *   \Symfony\Component\ClassLoader\ApcClassLoader.
   * @param string $environment
   *   String indicating the environment, e.g. 'prod' or 'dev'.
   * @param bool $allow_dumping
   *   (optional) FALSE to stop the container from being written to or read
   *   from disk. Defaults to TRUE.
   * @param string $app_root
   *   (optional) The path to the application root as a string. If not supplied,
   *   the application root will be computed.
   *
   * @return static
   *
   * @throws \Symfony\Component\HttpKernel\Exception\BadRequestHttpException
   *   In case the host name in the request is not trusted.
   */
  public static function createFromRequest(Request $request, $class_loader, $environment, $allow_dumping = TRUE, $app_root = NULL) {
    $kernel = new static($environment, $class_loader, $allow_dumping, $app_root);
    static::bootEnvironment($app_root);
    $kernel
      ->initializeSettings($request);
    return $kernel;
  }

  /**
   * Constructs a DrupalKernel object.
   *
   * @param string $environment
   *   String indicating the environment, e.g. 'prod' or 'dev'.
   * @param $class_loader
   *   The class loader. Normally \Composer\Autoload\ClassLoader, as included by
   *   the front controller, but may also be decorated; e.g.,
   *   \Symfony\Component\ClassLoader\ApcClassLoader.
   * @param bool $allow_dumping
   *   (optional) FALSE to stop the container from being written to or read
   *   from disk. Defaults to TRUE.
   * @param string $app_root
   *   (optional) The path to the application root as a string. If not supplied,
   *   the application root will be computed.
   */
  public function __construct($environment, $class_loader, $allow_dumping = TRUE, $app_root = NULL) {
    $this->environment = $environment;
    $this->classLoader = $class_loader;
    $this->allowDumping = $allow_dumping;
    if ($app_root === NULL) {
      $app_root = static::guessApplicationRoot();
    }
    $this->root = $app_root;
  }

  /**
   * Determine the application root directory based on this file's location.
   *
   * @return string
   *   The application root.
   */
  protected static function guessApplicationRoot() {

    // Determine the application root by:
    // - Removing the namespace directories from the path.
    // - Getting the path to the directory two levels up from the path
    //   determined in the previous step.
    return dirname(dirname(substr(__DIR__, 0, -strlen(__NAMESPACE__))));
  }

  /**
   * Returns the appropriate site directory for a request.
   *
   * Once the kernel has been created DrupalKernelInterface::getSitePath() is
   * preferred since it gets the statically cached result of this method.
   *
   * Site directories contain all site specific code. This includes settings.php
   * for bootstrap level configuration, file configuration stores, public file
   * storage and site specific modules and themes.
   *
   * A file named sites.php must be present in the sites directory for
   * multisite. If it doesn't exist, then 'sites/default' will be used.
   *
   * Finds a matching site directory file by stripping the website's hostname
   * from left to right and pathname from right to left. By default, the
   * directory must contain a 'settings.php' file for it to match. If the
   * parameter $require_settings is set to FALSE, then a directory without a
   * 'settings.php' file will match as well. The first configuration file found
   * will be used and the remaining ones will be ignored. If no configuration
   * file is found, returns a default value 'sites/default'. See
   * default.settings.php for examples on how the URL is converted to a
   * directory.
   *
   * The sites.php file in the sites directory can define aliases in an
   * associative array named $sites. The array is written in the format
   * '<port>.<domain>.<path>' => 'directory'. As an example, to create a
   * directory alias for https://www.drupal.org:8080/mysite/test whose
   * configuration file is in sites/example.com, the array should be defined as:
   * @code
   * $sites = array(
   *   '8080.www.drupal.org.mysite.test' => 'example.com',
   * );
   * @endcode
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The current request.
   * @param bool $require_settings
   *   Only directories with an existing settings.php file will be recognized.
   *   Defaults to TRUE. During initial installation, this is set to FALSE so
   *   that Drupal can detect a matching directory, then create a new
   *   settings.php file in it.
   * @param string $app_root
   *   (optional) The path to the application root as a string. If not supplied,
   *   the application root will be computed.
   *
   * @return string
   *   The path of the matching directory.
   *
   * @throws \Symfony\Component\HttpKernel\Exception\BadRequestHttpException
   *   In case the host name in the request is invalid.
   *
   * @see \Drupal\Core\DrupalKernelInterface::getSitePath()
   * @see \Drupal\Core\DrupalKernelInterface::setSitePath()
   * @see default.settings.php
   * @see example.sites.php
   */
  public static function findSitePath(Request $request, $require_settings = TRUE, $app_root = NULL) {
    if (static::validateHostname($request) === FALSE) {
      throw new BadRequestHttpException();
    }
    if ($app_root === NULL) {
      $app_root = static::guessApplicationRoot();
    }

    // Check for a simpletest override.
    if ($test_prefix = drupal_valid_test_ua()) {
      $test_db = new TestDatabase($test_prefix);
      return $test_db
        ->getTestSitePath();
    }

    // Determine whether multi-site functionality is enabled.
    if (!file_exists($app_root . '/sites/sites.php')) {
      return 'sites/default';
    }

    // Otherwise, use find the site path using the request.
    $script_name = $request->server
      ->get('SCRIPT_NAME');
    if (!$script_name) {
      $script_name = $request->server
        ->get('SCRIPT_FILENAME');
    }
    $http_host = $request
      ->getHttpHost();
    $sites = [];
    include $app_root . '/sites/sites.php';
    $uri = explode('/', $script_name);
    $server = explode('.', implode('.', array_reverse(explode(':', rtrim($http_host, '.')))));
    for ($i = count($uri) - 1; $i > 0; $i--) {
      for ($j = count($server); $j > 0; $j--) {
        $dir = implode('.', array_slice($server, -$j)) . implode('.', array_slice($uri, 0, $i));
        if (isset($sites[$dir]) && file_exists($app_root . '/sites/' . $sites[$dir])) {
          $dir = $sites[$dir];
        }
        if (file_exists($app_root . '/sites/' . $dir . '/settings.php') || !$require_settings && file_exists($app_root . '/sites/' . $dir)) {
          return "sites/{$dir}";
        }
      }
    }
    return 'sites/default';
  }

  /**
   * {@inheritdoc}
   */
  public function setSitePath($path) {
    if ($this->booted && $path !== $this->sitePath) {
      throw new \LogicException('Site path cannot be changed after calling boot()');
    }
    $this->sitePath = $path;
  }

  /**
   * {@inheritdoc}
   */
  public function getSitePath() {
    return $this->sitePath;
  }

  /**
   * {@inheritdoc}
   */
  public function getAppRoot() {
    return $this->root;
  }

  /**
   * {@inheritdoc}
   */
  public function boot() {
    if ($this->booted) {
      return $this;
    }

    // Ensure that findSitePath is set.
    if (!$this->sitePath) {
      throw new \Exception('Kernel does not have site path set before calling boot()');
    }

    // Initialize the FileCacheFactory component. We have to do it here instead
    // of in \Drupal\Component\FileCache\FileCacheFactory because we can not use
    // the Settings object in a component.
    $configuration = Settings::get('file_cache');

    // Provide a default configuration, if not set.
    if (!isset($configuration['default'])) {

      // @todo Use extension_loaded('apcu') for non-testbot
      //  https://www.drupal.org/node/2447753.
      if (function_exists('apcu_fetch')) {
        $configuration['default']['cache_backend_class'] = '\\Drupal\\Component\\FileCache\\ApcuFileCacheBackend';
      }
    }
    FileCacheFactory::setConfiguration($configuration);
    FileCacheFactory::setPrefix(Settings::getApcuPrefix('file_cache', $this->root));
    $this->bootstrapContainer = new $this->bootstrapContainerClass(Settings::get('bootstrap_container_definition', $this->defaultBootstrapContainerDefinition));

    // Initialize the container.
    $this
      ->initializeContainer();
    if (in_array('phar', stream_get_wrappers(), TRUE)) {

      // Set up a stream wrapper to handle insecurities due to PHP's builtin
      // phar stream wrapper. This is not registered as a regular stream wrapper
      // to prevent \Drupal\Core\File\FileSystem::validScheme() treating "phar"
      // as a valid scheme.
      try {
        $behavior = new PharStreamWrapperBehavior();
        PharStreamWrapperManager::initialize($behavior
          ->withAssertion(new PharExtensionInterceptor()));
      } catch (\LogicException $e) {

        // Continue if the PharStreamWrapperManager is already initialized. For
        // example, this occurs during a module install.
        // @see \Drupal\Core\Extension\ModuleInstaller::install()
      }
      stream_wrapper_unregister('phar');
      stream_wrapper_register('phar', PharStreamWrapper::class);
    }
    $this->booted = TRUE;
    return $this;
  }

  /**
   * {@inheritdoc}
   */
  public function shutdown() {
    if (FALSE === $this->booted) {
      return;
    }
    $this->container
      ->get('stream_wrapper_manager')
      ->unregister();
    $this->booted = FALSE;
    $this->container = NULL;
    $this->moduleList = NULL;
    $this->moduleData = [];
  }

  /**
   * {@inheritdoc}
   */
  public function getContainer() {
    return $this->container;
  }

  /**
   * {@inheritdoc}
   */
  public function setContainer(ContainerInterface $container = NULL) {
    if (isset($this->container)) {
      throw new \Exception('The container should not override an existing container.');
    }
    if ($this->booted) {
      throw new \Exception('The container cannot be set after a booted kernel.');
    }
    $this->container = $container;
    return $this;
  }

  /**
   * {@inheritdoc}
   */
  public function getCachedContainerDefinition() {
    $cache = $this->bootstrapContainer
      ->get('cache.container')
      ->get($this
      ->getContainerCacheKey());
    if ($cache) {
      return $cache->data;
    }
    return NULL;
  }

  /**
   * {@inheritdoc}
   */
  public function loadLegacyIncludes() {
    require_once $this->root . '/core/includes/common.inc';
    require_once $this->root . '/core/includes/database.inc';
    require_once $this->root . '/core/includes/module.inc';
    require_once $this->root . '/core/includes/theme.inc';
    require_once $this->root . '/core/includes/pager.inc';
    require_once $this->root . '/core/includes/menu.inc';
    require_once $this->root . '/core/includes/tablesort.inc';
    require_once $this->root . '/core/includes/file.inc';
    require_once $this->root . '/core/includes/unicode.inc';
    require_once $this->root . '/core/includes/form.inc';
    require_once $this->root . '/core/includes/errors.inc';
    require_once $this->root . '/core/includes/schema.inc';
    require_once $this->root . '/core/includes/entity.inc';
  }

  /**
   * {@inheritdoc}
   */
  public function preHandle(Request $request) {

    // Sanitize the request.
    $request = RequestSanitizer::sanitize($request, (array) Settings::get(RequestSanitizer::SANITIZE_WHITELIST, []), (bool) Settings::get(RequestSanitizer::SANITIZE_LOG, FALSE));
    $this
      ->loadLegacyIncludes();

    // Load all enabled modules.
    $this->container
      ->get('module_handler')
      ->loadAll();

    // Register stream wrappers.
    $this->container
      ->get('stream_wrapper_manager')
      ->register();

    // Initialize legacy request globals.
    $this
      ->initializeRequestGlobals($request);

    // Put the request on the stack.
    $this->container
      ->get('request_stack')
      ->push($request);

    // Set the allowed protocols.
    UrlHelper::setAllowedProtocols($this->container
      ->getParameter('filter_protocols'));

    // Override of Symfony's MIME type guesser singleton.
    MimeTypeGuesser::registerWithSymfonyGuesser($this->container);
    $this->prepared = TRUE;
  }

  /**
   * {@inheritdoc}
   */
  public function discoverServiceProviders() {
    $this->serviceYamls = [
      'app' => [],
      'site' => [],
    ];
    $this->serviceProviderClasses = [
      'app' => [],
      'site' => [],
    ];
    $this->serviceYamls['app']['core'] = 'core/core.services.yml';
    $this->serviceProviderClasses['app']['core'] = 'Drupal\\Core\\CoreServiceProvider';

    // Retrieve enabled modules and register their namespaces.
    if (!isset($this->moduleList)) {
      $extensions = $this
        ->getConfigStorage()
        ->read('core.extension');

      // If core.extension configuration does not exist and we're not in the
      // installer itself, then we need to put the kernel into a pre-installer
      // mode. The container should not be dumped because Drupal is yet to be
      // installed. The installer service provider is registered to ensure that
      // cache and other automatically created tables are not created if
      // database settings are available. None of this is required when the
      // installer is running because the installer has its own kernel and
      // manages the addition of its own service providers.
      // @see install_begin_request()
      if ($extensions === FALSE && !InstallerKernel::installationAttempted()) {
        $this->allowDumping = FALSE;
        $this->containerNeedsDumping = FALSE;
        $GLOBALS['conf']['container_service_providers']['InstallerServiceProvider'] = 'Drupal\\Core\\Installer\\InstallerServiceProvider';
      }
      $this->moduleList = isset($extensions['module']) ? $extensions['module'] : [];
    }
    $module_filenames = $this
      ->getModuleFileNames();
    $this
      ->classLoaderAddMultiplePsr4($this
      ->getModuleNamespacesPsr4($module_filenames));

    // Load each module's serviceProvider class.
    foreach ($module_filenames as $module => $filename) {
      $camelized = ContainerBuilder::camelize($module);
      $name = "{$camelized}ServiceProvider";
      $class = "Drupal\\{$module}\\{$name}";
      if (class_exists($class)) {
        $this->serviceProviderClasses['app'][$module] = $class;
      }
      $filename = dirname($filename) . "/{$module}.services.yml";
      if (file_exists($filename)) {
        $this->serviceYamls['app'][$module] = $filename;
      }
    }

    // Add site-specific service providers.
    if (!empty($GLOBALS['conf']['container_service_providers'])) {
      foreach ($GLOBALS['conf']['container_service_providers'] as $class) {
        if (is_string($class) && class_exists($class) || is_object($class) && ($class instanceof ServiceProviderInterface || $class instanceof ServiceModifierInterface)) {
          $this->serviceProviderClasses['site'][] = $class;
        }
      }
    }
    $this
      ->addServiceFiles(Settings::get('container_yamls', []));
  }

  /**
   * {@inheritdoc}
   */
  public function getServiceProviders($origin) {
    return $this->serviceProviders[$origin];
  }

  /**
   * {@inheritdoc}
   */
  public function terminate(Request $request, Response $response) {

    // Only run terminate() when essential services have been set up properly
    // by preHandle() before.
    if (FALSE === $this->prepared) {
      return;
    }
    if ($this
      ->getHttpKernel() instanceof TerminableInterface) {
      $this
        ->getHttpKernel()
        ->terminate($request, $response);
    }
  }

  /**
   * {@inheritdoc}
   */
  public function handle(Request $request, $type = self::MASTER_REQUEST, $catch = TRUE) {

    // Ensure sane PHP environment variables.
    static::bootEnvironment();
    try {
      $this
        ->initializeSettings($request);

      // Redirect the user to the installation script if Drupal has not been
      // installed yet (i.e., if no $databases array has been defined in the
      // settings.php file) and we are not already installing.
      if (!Database::getConnectionInfo() && !InstallerKernel::installationAttempted() && PHP_SAPI !== 'cli') {
        $response = new RedirectResponse($request
          ->getBasePath() . '/core/install.php', 302, [
          'Cache-Control' => 'no-cache',
        ]);
      }
      else {
        $this
          ->boot();
        $response = $this
          ->getHttpKernel()
          ->handle($request, $type, $catch);
      }
    } catch (\Exception $e) {
      if ($catch === FALSE) {
        throw $e;
      }
      $response = $this
        ->handleException($e, $request, $type);
    }

    // Adapt response headers to the current request.
    $response
      ->prepare($request);
    return $response;
  }

  /**
   * Converts an exception into a response.
   *
   * @param \Exception $e
   *   An exception
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   A Request instance
   * @param int $type
   *   The type of the request (one of HttpKernelInterface::MASTER_REQUEST or
   *   HttpKernelInterface::SUB_REQUEST)
   *
   * @return \Symfony\Component\HttpFoundation\Response
   *   A Response instance
   *
   * @throws \Exception
   *   If the passed in exception cannot be turned into a response.
   */
  protected function handleException(\Exception $e, $request, $type) {
    if ($this
      ->shouldRedirectToInstaller($e, $this->container ? $this->container
      ->get('database') : NULL)) {
      return new RedirectResponse($request
        ->getBasePath() . '/core/install.php', 302, [
        'Cache-Control' => 'no-cache',
      ]);
    }
    if ($e instanceof HttpExceptionInterface) {
      $response = new Response($e
        ->getMessage(), $e
        ->getStatusCode());
      $response->headers
        ->add($e
        ->getHeaders());
      return $response;
    }
    throw $e;
  }

  /**
   * {@inheritdoc}
   */
  public function prepareLegacyRequest(Request $request) {
    $this
      ->boot();
    $this
      ->preHandle($request);

    // Setup services which are normally initialized from within stack
    // middleware or during the request kernel event.
    if (PHP_SAPI !== 'cli') {
      $request
        ->setSession($this->container
        ->get('session'));
    }
    $request->attributes
      ->set(RouteObjectInterface::ROUTE_OBJECT, new Route('<none>'));
    $request->attributes
      ->set(RouteObjectInterface::ROUTE_NAME, '<none>');
    $this->container
      ->get('request_stack')
      ->push($request);
    $this->container
      ->get('router.request_context')
      ->fromRequest($request);
    @trigger_error(__NAMESPACE__ . '\\DrupalKernel::prepareLegacyRequest is deprecated drupal:8.0.0 and is removed from drupal:9.0.0. Use DrupalKernel::boot() and DrupalKernel::preHandle() instead. See https://www.drupal.org/node/3070678', E_USER_DEPRECATED);
    return $this;
  }

  /**
   * Returns module data on the filesystem.
   *
   * @param $module
   *   The name of the module.
   *
   * @return \Drupal\Core\Extension\Extension|bool
   *   Returns an Extension object if the module is found, FALSE otherwise.
   */
  protected function moduleData($module) {
    if (!$this->moduleData) {

      // First, find profiles.
      $listing = new ExtensionDiscovery($this->root);
      $listing
        ->setProfileDirectories([]);
      $all_profiles = $listing
        ->scan('profile');
      $profiles = array_intersect_key($all_profiles, $this->moduleList);
      $profile_directories = array_map(function ($profile) {
        return $profile
          ->getPath();
      }, $profiles);
      $listing
        ->setProfileDirectories($profile_directories);

      // Now find modules.
      $this->moduleData = $profiles + $listing
        ->scan('module');
    }
    return isset($this->moduleData[$module]) ? $this->moduleData[$module] : FALSE;
  }

  /**
   * Implements Drupal\Core\DrupalKernelInterface::updateModules().
   *
   * @todo Remove obsolete $module_list parameter. Only $module_filenames is
   *   needed.
   */
  public function updateModules(array $module_list, array $module_filenames = []) {
    $pre_existing_module_namespaces = [];
    if ($this->booted && is_array($this->moduleList)) {
      $pre_existing_module_namespaces = $this
        ->getModuleNamespacesPsr4($this
        ->getModuleFileNames());
    }
    $this->moduleList = $module_list;
    foreach ($module_filenames as $name => $extension) {
      $this->moduleData[$name] = $extension;
    }

    // If we haven't yet booted, we don't need to do anything: the new module
    // list will take effect when boot() is called. However we set a
    // flag that the container needs a rebuild, so that a potentially cached
    // container is not used. If we have already booted, then rebuild the
    // container in order to refresh the serviceProvider list and container.
    $this->containerNeedsRebuild = TRUE;
    if ($this->booted) {

      // We need to register any new namespaces to a new class loader because
      // the current class loader might have stored a negative result for a
      // class that is now available.
      // @see \Composer\Autoload\ClassLoader::findFile()
      $new_namespaces = array_diff_key($this
        ->getModuleNamespacesPsr4($this
        ->getModuleFileNames()), $pre_existing_module_namespaces);
      if (!empty($new_namespaces)) {
        $additional_class_loader = new ClassLoader();
        $this
          ->classLoaderAddMultiplePsr4($new_namespaces, $additional_class_loader);
        $additional_class_loader
          ->register();
      }
      $this
        ->initializeContainer();
    }
  }

  /**
   * Returns the container cache key based on the environment.
   *
   * The 'environment' consists of:
   * - The kernel environment string.
   * - The Drupal version constant.
   * - The deployment identifier from settings.php. This allows custom
   *   deployments to force a container rebuild.
   * - The operating system running PHP. This allows compiler passes to optimize
   *   services for different operating systems.
   * - The paths to any additional container YAMLs from settings.php.
   *
   * @return string
   *   The cache key used for the service container.
   */
  protected function getContainerCacheKey() {
    $parts = [
      'service_container',
      $this->environment,
      \Drupal::VERSION,
      Settings::get('deployment_identifier'),
      PHP_OS,
      serialize(Settings::get('container_yamls')),
    ];
    return implode(':', $parts);
  }

  /**
   * Returns the kernel parameters.
   *
   * @return array An array of kernel parameters
   */
  protected function getKernelParameters() {
    return [
      'kernel.environment' => $this->environment,
    ];
  }

  /**
   * Initializes the service container.
   *
   * @return \Symfony\Component\DependencyInjection\ContainerInterface
   */
  protected function initializeContainer() {
    $this->containerNeedsDumping = FALSE;
    $session_started = FALSE;
    if (isset($this->container)) {

      // Save the id of the currently logged in user.
      if ($this->container
        ->initialized('current_user')) {
        $current_user_id = $this->container
          ->get('current_user')
          ->id();
      }

      // If there is a session, close and save it.
      if ($this->container
        ->initialized('session')) {
        $session = $this->container
          ->get('session');
        if ($session
          ->isStarted()) {
          $session_started = TRUE;
          $session
            ->save();
        }
        unset($session);
      }
    }

    // If we haven't booted yet but there is a container, then we're asked to
    // boot the container injected via setContainer().
    // @see \Drupal\KernelTests\KernelTestBase::setUp()
    if (isset($this->container) && !$this->booted) {
      $container = $this->container;
    }

    // If the module list hasn't already been set in updateModules and we are
    // not forcing a rebuild, then try and load the container from the cache.
    if (empty($this->moduleList) && !$this->containerNeedsRebuild) {
      $container_definition = $this
        ->getCachedContainerDefinition();
    }

    // If there is no container and no cached container definition, build a new
    // one from scratch.
    if (!isset($container) && !isset($container_definition)) {
      $container = $this
        ->compileContainer();

      // Only dump the container if dumping is allowed. This is useful for
      // KernelTestBase, which never wants to use the real container, but always
      // the container builder.
      if ($this->allowDumping) {
        $dumper = new $this->phpArrayDumperClass($container);
        $container_definition = $dumper
          ->getArray();
      }
    }

    // The container was rebuilt successfully.
    $this->containerNeedsRebuild = FALSE;

    // Only create a new class if we have a container definition.
    if (isset($container_definition)) {
      $class = Settings::get('container_base_class', '\\Drupal\\Core\\DependencyInjection\\Container');
      $container = new $class($container_definition);
    }
    $this
      ->attachSynthetic($container);
    $this->container = $container;
    if ($session_started) {
      $this->container
        ->get('session')
        ->start();
    }

    // The request stack is preserved across container rebuilds. Reinject the
    // new session into the master request if one was present before.
    if ($request_stack = $this->container
      ->get('request_stack', ContainerInterface::NULL_ON_INVALID_REFERENCE)) {
      if ($request = $request_stack
        ->getMasterRequest()) {
        $subrequest = TRUE;
        if ($request
          ->hasSession()) {
          $request
            ->setSession($this->container
            ->get('session'));
        }
      }
    }
    if (!empty($current_user_id)) {
      $this->container
        ->get('current_user')
        ->setInitialAccountId($current_user_id);
    }
    \Drupal::setContainer($this->container);

    // Allow other parts of the codebase to react on container initialization in
    // subrequest.
    if (!empty($subrequest)) {
      $this->container
        ->get('event_dispatcher')
        ->dispatch(self::CONTAINER_INITIALIZE_SUBREQUEST_FINISHED);
    }

    // If needs dumping flag was set, dump the container.
    if ($this->containerNeedsDumping && !$this
      ->cacheDrupalContainer($container_definition)) {
      $this->container
        ->get('logger.factory')
        ->get('DrupalKernel')
        ->error('Container cannot be saved to cache.');
    }
    return $this->container;
  }

  /**
   * Setup a consistent PHP environment.
   *
   * This method sets PHP environment options we want to be sure are set
   * correctly for security or just saneness.
   *
   * @param string $app_root
   *   (optional) The path to the application root as a string. If not supplied,
   *   the application root will be computed.
   */
  public static function bootEnvironment($app_root = NULL) {
    if (static::$isEnvironmentInitialized) {
      return;
    }

    // Determine the application root if it's not supplied.
    if ($app_root === NULL) {
      $app_root = static::guessApplicationRoot();
    }

    // Include our bootstrap file.
    require_once $app_root . '/core/includes/bootstrap.inc';

    // Enforce E_STRICT, but allow users to set levels not part of E_STRICT.
    error_reporting(E_STRICT | E_ALL);

    // Override PHP settings required for Drupal to work properly.
    // sites/default/default.settings.php contains more runtime settings.
    // The .htaccess file contains settings that cannot be changed at runtime.
    if (PHP_SAPI !== 'cli') {

      // Use session cookies, not transparent sessions that puts the session id
      // in the query string.
      ini_set('session.use_cookies', '1');
      ini_set('session.use_only_cookies', '1');
      ini_set('session.use_trans_sid', '0');

      // Don't send HTTP headers using PHP's session handler.
      // Send an empty string to disable the cache limiter.
      ini_set('session.cache_limiter', '');

      // Use httponly session cookies.
      ini_set('session.cookie_httponly', '1');
    }

    // Set sane locale settings, to ensure consistent string, dates, times and
    // numbers handling.
    setlocale(LC_ALL, 'C');

    // Set appropriate configuration for multi-byte strings.
    mb_internal_encoding('utf-8');
    mb_language('uni');

    // Indicate that code is operating in a test child site.
    if (!defined('DRUPAL_TEST_IN_CHILD_SITE')) {
      if ($test_prefix = drupal_valid_test_ua()) {
        $test_db = new TestDatabase($test_prefix);

        // Only code that interfaces directly with tests should rely on this
        // constant; e.g., the error/exception handler conditionally adds further
        // error information into HTTP response headers that are consumed by
        // Simpletest's internal browser.
        define('DRUPAL_TEST_IN_CHILD_SITE', TRUE);

        // Web tests are to be conducted with runtime assertions active.
        assert_options(ASSERT_ACTIVE, TRUE);
        Handle::register();

        // Log fatal errors to the test site directory.
        ini_set('log_errors', 1);
        ini_set('error_log', $app_root . '/' . $test_db
          ->getTestSitePath() . '/error.log');

        // Ensure that a rewritten settings.php is used if opcache is on.
        ini_set('opcache.validate_timestamps', 'on');
        ini_set('opcache.revalidate_freq', 0);
      }
      else {

        // Ensure that no other code defines this.
        define('DRUPAL_TEST_IN_CHILD_SITE', FALSE);
      }
    }

    // Set the Drupal custom error handler.
    set_error_handler('_drupal_error_handler');
    set_exception_handler('_drupal_exception_handler');
    static::$isEnvironmentInitialized = TRUE;
  }

  /**
   * Locate site path and initialize settings singleton.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The current request.
   *
   * @throws \Symfony\Component\HttpKernel\Exception\BadRequestHttpException
   *   In case the host name in the request is not trusted.
   */
  protected function initializeSettings(Request $request) {
    $site_path = static::findSitePath($request);
    $this
      ->setSitePath($site_path);
    $class_loader_class = get_class($this->classLoader);
    Settings::initialize($this->root, $site_path, $this->classLoader);

    // Initialize our list of trusted HTTP Host headers to protect against
    // header attacks.
    $host_patterns = Settings::get('trusted_host_patterns', []);
    if (PHP_SAPI !== 'cli' && !empty($host_patterns)) {
      if (static::setupTrustedHosts($request, $host_patterns) === FALSE) {
        throw new BadRequestHttpException('The provided host name is not valid for this server.');
      }
    }

    // If the class loader is still the same, possibly
    // upgrade to an optimized class loader.
    if ($class_loader_class == get_class($this->classLoader) && Settings::get('class_loader_auto_detect', TRUE)) {
      $prefix = Settings::getApcuPrefix('class_loader', $this->root);
      $loader = NULL;

      // We autodetect one of the following three optimized classloaders, if
      // their underlying extension exists.
      if (function_exists('apcu_fetch')) {
        $loader = new ApcClassLoader($prefix, $this->classLoader);
      }
      elseif (extension_loaded('wincache')) {
        $loader = new WinCacheClassLoader($prefix, $this->classLoader);
      }
      elseif (extension_loaded('xcache')) {
        $loader = new XcacheClassLoader($prefix, $this->classLoader);
      }
      if (!empty($loader)) {
        $this->classLoader
          ->unregister();

        // The optimized classloader might be persistent and store cache misses.
        // For example, once a cache miss is stored in APCu clearing it on a
        // specific web-head will not clear any other web-heads. Therefore
        // fallback to the composer class loader that only statically caches
        // misses.
        $old_loader = $this->classLoader;
        $this->classLoader = $loader;

        // Our class loaders are prepended to ensure they come first like the
        // class loader they are replacing.
        $old_loader
          ->register(TRUE);
        $loader
          ->register(TRUE);
      }
    }
  }

  /**
   * Bootstraps the legacy global request variables.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The current request.
   *
   * @todo D8: Eliminate this entirely in favor of Request object.
   */
  protected function initializeRequestGlobals(Request $request) {
    global $base_url;

    // Set and derived from $base_url by this function.
    global $base_path, $base_root;
    global $base_secure_url, $base_insecure_url;

    // Create base URL.
    $base_root = $request
      ->getSchemeAndHttpHost();
    $base_url = $base_root;

    // For a request URI of '/index.php/foo', $_SERVER['SCRIPT_NAME'] is
    // '/index.php', whereas $_SERVER['PHP_SELF'] is '/index.php/foo'.
    if ($dir = rtrim(dirname($request->server
      ->get('SCRIPT_NAME')), '\\/')) {

      // Remove "core" directory if present, allowing install.php,
      // authorize.php, and others to auto-detect a base path.
      $core_position = strrpos($dir, '/core');
      if ($core_position !== FALSE && strlen($dir) - 5 == $core_position) {
        $base_path = substr($dir, 0, $core_position);
      }
      else {
        $base_path = $dir;
      }
      $base_url .= $base_path;
      $base_path .= '/';
    }
    else {
      $base_path = '/';
    }
    $base_secure_url = str_replace('http://', 'https://', $base_url);
    $base_insecure_url = str_replace('https://', 'http://', $base_url);
  }

  /**
   * Returns service instances to persist from an old container to a new one.
   */
  protected function getServicesToPersist(ContainerInterface $container) {
    $persist = [];
    foreach ($container
      ->getParameter('persist_ids') as $id) {

      // It's pointless to persist services not yet initialized.
      if ($container
        ->initialized($id)) {
        $persist[$id] = $container
          ->get($id);
      }
    }
    return $persist;
  }

  /**
   * Moves persistent service instances into a new container.
   */
  protected function persistServices(ContainerInterface $container, array $persist) {
    foreach ($persist as $id => $object) {

      // Do not override services already set() on the new container, for
      // example 'service_container'.
      if (!$container
        ->initialized($id)) {
        $container
          ->set($id, $object);
      }
    }
  }

  /**
   * {@inheritdoc}
   */
  public function rebuildContainer() {

    // Empty module properties and for them to be reloaded from scratch.
    $this->moduleList = NULL;
    $this->moduleData = [];
    $this->containerNeedsRebuild = TRUE;
    return $this
      ->initializeContainer();
  }

  /**
   * {@inheritdoc}
   */
  public function invalidateContainer() {

    // An invalidated container needs a rebuild.
    $this->containerNeedsRebuild = TRUE;

    // If we have not yet booted, settings or bootstrap services might not yet
    // be available. In that case the container will not be loaded from cache
    // due to the above setting when the Kernel is booted.
    if (!$this->booted) {
      return;
    }

    // Also remove the container definition from the cache backend.
    $this->bootstrapContainer
      ->get('cache.container')
      ->deleteAll();
  }

  /**
   * Attach synthetic values on to kernel.
   *
   * @param \Symfony\Component\DependencyInjection\ContainerInterface $container
   *   Container object
   *
   * @return \Symfony\Component\DependencyInjection\ContainerInterface
   */
  protected function attachSynthetic(ContainerInterface $container) {
    $persist = [];
    if (isset($this->container)) {
      $persist = $this
        ->getServicesToPersist($this->container);
    }
    $this
      ->persistServices($container, $persist);

    // All namespaces must be registered before we attempt to use any service
    // from the container.
    $this
      ->classLoaderAddMultiplePsr4($container
      ->getParameter('container.namespaces'));
    $container
      ->set('kernel', $this);

    // Set the class loader which was registered as a synthetic service.
    $container
      ->set('class_loader', $this->classLoader);
    return $container;
  }

  /**
   * Compiles a new service container.
   *
   * @return \Drupal\Core\DependencyInjection\ContainerBuilder The compiled service container
   */
  protected function compileContainer() {

    // We are forcing a container build so it is reasonable to assume that the
    // calling method knows something about the system has changed requiring the
    // container to be dumped to the filesystem.
    if ($this->allowDumping) {
      $this->containerNeedsDumping = TRUE;
    }
    $this
      ->initializeServiceProviders();
    $container = $this
      ->getContainerBuilder();
    $container
      ->set('kernel', $this);
    $container
      ->setParameter('container.modules', $this
      ->getModulesParameter());
    $container
      ->setParameter('install_profile', $this
      ->getInstallProfile());

    // Get a list of namespaces and put it onto the container.
    $namespaces = $this
      ->getModuleNamespacesPsr4($this
      ->getModuleFileNames());

    // Add all components in \Drupal\Core and \Drupal\Component that have one of
    // the following directories:
    // - Element
    // - Entity
    // - Plugin
    foreach ([
      'Core',
      'Component',
    ] as $parent_directory) {
      $path = 'core/lib/Drupal/' . $parent_directory;
      $parent_namespace = 'Drupal\\' . $parent_directory;
      foreach (new \DirectoryIterator($this->root . '/' . $path) as $component) {

        /** @var $component \DirectoryIterator */
        $pathname = $component
          ->getPathname();
        if (!$component
          ->isDot() && $component
          ->isDir() && (is_dir($pathname . '/Plugin') || is_dir($pathname . '/Entity') || is_dir($pathname . '/Element'))) {
          $namespaces[$parent_namespace . '\\' . $component
            ->getFilename()] = $path . '/' . $component
            ->getFilename();
        }
      }
    }
    $container
      ->setParameter('container.namespaces', $namespaces);

    // Store the default language values on the container. This is so that the
    // default language can be configured using the configuration factory. This
    // avoids the circular dependencies that would created by
    // \Drupal\language\LanguageServiceProvider::alter() and allows the default
    // language to not be English in the installer.
    $default_language_values = Language::$defaultValues;
    if ($system = $this
      ->getConfigStorage()
      ->read('system.site')) {
      if ($default_language_values['id'] != $system['langcode']) {
        $default_language_values = [
          'id' => $system['langcode'],
        ];
      }
    }
    $container
      ->setParameter('language.default_values', $default_language_values);

    // Register synthetic services.
    $container
      ->register('class_loader')
      ->setSynthetic(TRUE);
    $container
      ->register('kernel', 'Symfony\\Component\\HttpKernel\\KernelInterface')
      ->setSynthetic(TRUE);
    $container
      ->register('service_container', 'Symfony\\Component\\DependencyInjection\\ContainerInterface')
      ->setSynthetic(TRUE);

    // Register application services.
    $yaml_loader = new YamlFileLoader($container);
    foreach ($this->serviceYamls['app'] as $filename) {
      $yaml_loader
        ->load($filename);
    }
    foreach ($this->serviceProviders['app'] as $provider) {
      if ($provider instanceof ServiceProviderInterface) {
        $provider
          ->register($container);
      }
    }

    // Register site-specific service overrides.
    foreach ($this->serviceYamls['site'] as $filename) {
      $yaml_loader
        ->load($filename);
    }
    foreach ($this->serviceProviders['site'] as $provider) {
      if ($provider instanceof ServiceProviderInterface) {
        $provider
          ->register($container);
      }
    }

    // Identify all services whose instances should be persisted when rebuilding
    // the container during the lifetime of the kernel (e.g., during a kernel
    // reboot). Include synthetic services, because by definition, they cannot
    // be automatically reinstantiated. Also include services tagged to persist.
    $persist_ids = [];
    foreach ($container
      ->getDefinitions() as $id => $definition) {

      // It does not make sense to persist the container itself, exclude it.
      if ($id !== 'service_container' && ($definition
        ->isSynthetic() || $definition
        ->getTag('persist'))) {
        $persist_ids[] = $id;
      }
    }
    $container
      ->setParameter('persist_ids', $persist_ids);
    $container
      ->compile();
    return $container;
  }

  /**
   * Registers all service providers to the kernel.
   *
   * @throws \LogicException
   */
  protected function initializeServiceProviders() {
    $this
      ->discoverServiceProviders();
    $this->serviceProviders = [
      'app' => [],
      'site' => [],
    ];
    foreach ($this->serviceProviderClasses as $origin => $classes) {
      foreach ($classes as $name => $class) {
        if (!is_object($class)) {
          $this->serviceProviders[$origin][$name] = new $class();
        }
        else {
          $this->serviceProviders[$origin][$name] = $class;
        }
      }
    }
  }

  /**
   * Gets a new ContainerBuilder instance used to build the service container.
   *
   * @return \Drupal\Core\DependencyInjection\ContainerBuilder
   */
  protected function getContainerBuilder() {
    return new ContainerBuilder(new ParameterBag($this
      ->getKernelParameters()));
  }

  /**
   * Stores the container definition in a cache.
   *
   * @param array $container_definition
   *   The container definition to cache.
   *
   * @return bool
   *   TRUE if the container was successfully cached.
   */
  protected function cacheDrupalContainer(array $container_definition) {
    $saved = TRUE;
    try {
      $this->bootstrapContainer
        ->get('cache.container')
        ->set($this
        ->getContainerCacheKey(), $container_definition);
    } catch (\Exception $e) {

      // There is no way to get from the Cache API if the cache set was
      // successful or not, hence an Exception is caught and the caller informed
      // about the error condition.
      $saved = FALSE;
    }
    return $saved;
  }

  /**
   * Gets a http kernel from the container
   *
   * @return \Symfony\Component\HttpKernel\HttpKernelInterface
   */
  protected function getHttpKernel() {
    return $this->container
      ->get('http_kernel');
  }

  /**
   * Returns the active configuration storage to use during building the container.
   *
   * @return \Drupal\Core\Config\StorageInterface
   */
  protected function getConfigStorage() {
    if (!isset($this->configStorage)) {

      // The active configuration storage may not exist yet; e.g., in the early
      // installer. Catch the exception thrown by config_get_config_directory().
      try {
        $this->configStorage = BootstrapConfigStorageFactory::get($this->classLoader);
      } catch (\Exception $e) {
        $this->configStorage = new NullStorage();
      }
    }
    return $this->configStorage;
  }

  /**
   * Returns an array of Extension class parameters for all enabled modules.
   *
   * @return array
   */
  protected function getModulesParameter() {
    $extensions = [];
    foreach ($this->moduleList as $name => $weight) {
      if ($data = $this
        ->moduleData($name)) {
        $extensions[$name] = [
          'type' => $data
            ->getType(),
          'pathname' => $data
            ->getPathname(),
          'filename' => $data
            ->getExtensionFilename(),
        ];
      }
    }
    return $extensions;
  }

  /**
   * Gets the file name for each enabled module.
   *
   * @return array
   *   Array where each key is a module name, and each value is a path to the
   *   respective *.info.yml file.
   */
  protected function getModuleFileNames() {
    $filenames = [];
    foreach ($this->moduleList as $module => $weight) {
      if ($data = $this
        ->moduleData($module)) {
        $filenames[$module] = $data
          ->getPathname();
      }
    }
    return $filenames;
  }

  /**
   * Gets the PSR-4 base directories for module namespaces.
   *
   * @param string[] $module_file_names
   *   Array where each key is a module name, and each value is a path to the
   *   respective *.info.yml file.
   *
   * @return string[]
   *   Array where each key is a module namespace like 'Drupal\system', and each
   *   value is the PSR-4 base directory associated with the module namespace.
   */
  protected function getModuleNamespacesPsr4($module_file_names) {
    $namespaces = [];
    foreach ($module_file_names as $module => $filename) {
      $namespaces["Drupal\\{$module}"] = dirname($filename) . '/src';
    }
    return $namespaces;
  }

  /**
   * Registers a list of namespaces with PSR-4 directories for class loading.
   *
   * @param array $namespaces
   *   Array where each key is a namespace like 'Drupal\system', and each value
   *   is either a PSR-4 base directory, or an array of PSR-4 base directories
   *   associated with this namespace.
   * @param object $class_loader
   *   The class loader. Normally \Composer\Autoload\ClassLoader, as included by
   *   the front controller, but may also be decorated; e.g.,
   *   \Symfony\Component\ClassLoader\ApcClassLoader.
   */
  protected function classLoaderAddMultiplePsr4(array $namespaces = [], $class_loader = NULL) {
    if ($class_loader === NULL) {
      $class_loader = $this->classLoader;
    }
    foreach ($namespaces as $prefix => $paths) {
      if (is_array($paths)) {
        foreach ($paths as $key => $value) {
          $paths[$key] = $this->root . '/' . $value;
        }
      }
      elseif (is_string($paths)) {
        $paths = $this->root . '/' . $paths;
      }
      $class_loader
        ->addPsr4($prefix . '\\', $paths);
    }
  }

  /**
   * Validates a hostname length.
   *
   * @param string $host
   *   A hostname.
   *
   * @return bool
   *   TRUE if the length is appropriate, or FALSE otherwise.
   */
  protected static function validateHostnameLength($host) {

    // Limit the length of the host name to 1000 bytes to prevent DoS attacks
    // with long host names.
    return strlen($host) <= 1000 && substr_count($host, '.') <= 100 && substr_count($host, ':') <= 100;
  }

  /**
   * Validates the hostname supplied from the HTTP request.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The request object
   *
   * @return bool
   *   TRUE if the hostname is valid, or FALSE otherwise.
   */
  public static function validateHostname(Request $request) {

    // $request->getHost() can throw an UnexpectedValueException if it
    // detects a bad hostname, but it does not validate the length.
    try {
      $http_host = $request
        ->getHost();
    } catch (\UnexpectedValueException $e) {
      return FALSE;
    }
    if (static::validateHostnameLength($http_host) === FALSE) {
      return FALSE;
    }
    return TRUE;
  }

  /**
   * Sets up the lists of trusted HTTP Host headers.
   *
   * Since the HTTP Host header can be set by the user making the request, it
   * is possible to create an attack vectors against a site by overriding this.
   * Symfony provides a mechanism for creating a list of trusted Host values.
   *
   * Host patterns (as regular expressions) can be configured through
   * settings.php for multisite installations, sites using ServerAlias without
   * canonical redirection, or configurations where the site responds to default
   * requests. For example,
   *
   * @code
   * $settings['trusted_host_patterns'] = array(
   *   '^example\.com$',
   *   '^*.example\.com$',
   * );
   * @endcode
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The request object.
   * @param array $host_patterns
   *   The array of trusted host patterns.
   *
   * @return bool
   *   TRUE if the Host header is trusted, FALSE otherwise.
   *
   * @see https://www.drupal.org/docs/8/install/trusted-host-settings
   * @see \Drupal\Core\Http\TrustedHostsRequestFactory
   */
  protected static function setupTrustedHosts(Request $request, $host_patterns) {
    $request
      ->setTrustedHosts($host_patterns);

    // Get the host, which will validate the current request.
    try {
      $host = $request
        ->getHost();

      // Fake requests created through Request::create() without passing in the
      // server variables from the main request have a default host of
      // 'localhost'. If 'localhost' does not match any of the trusted host
      // patterns these fake requests would fail the host verification. Instead,
      // TrustedHostsRequestFactory makes sure to pass in the server variables
      // from the main request.
      $request_factory = new TrustedHostsRequestFactory($host);
      Request::setFactory([
        $request_factory,
        'createRequest',
      ]);
    } catch (\UnexpectedValueException $e) {
      return FALSE;
    }
    return TRUE;
  }

  /**
   * Add service files.
   *
   * @param string[] $service_yamls
   *   A list of service files.
   */
  protected function addServiceFiles(array $service_yamls) {
    $this->serviceYamls['site'] = array_filter($service_yamls, 'file_exists');
  }

  /**
   * Gets the active install profile.
   *
   * @return string|null
   *   The name of the any active install profile or distribution.
   */
  protected function getInstallProfile() {
    $config = $this
      ->getConfigStorage()
      ->read('core.extension');
    if (isset($config['profile'])) {
      $install_profile = $config['profile'];
    }
    else {

      // If system_update_8300() has not yet run fallback to using settings.
      $settings = Settings::getAll();
      $install_profile = isset($settings['install_profile']) ? $settings['install_profile'] : NULL;
    }

    // Normalize an empty string to a NULL value.
    return empty($install_profile) ? NULL : $install_profile;
  }

}

Members

Name	Modifiers	Type	Description	Overrides
DrupalKernel::$allowDumping	protected	property	Whether the container can be dumped.
DrupalKernel::$booted	protected	property	Whether the kernel has been booted.
DrupalKernel::$bootstrapContainer	protected	property	Holds the bootstrap container.
DrupalKernel::$bootstrapContainerClass	protected	property	Holds the class used for instantiating the bootstrap container.
DrupalKernel::$classLoader	protected	property	The class loader object.
DrupalKernel::$configStorage	protected	property	Config storage object used for reading enabled modules configuration.
DrupalKernel::$container	protected	property	Holds the container instance.
DrupalKernel::$containerNeedsDumping	protected	property	Whether the container needs to be dumped once booting is complete.
DrupalKernel::$containerNeedsRebuild	protected	property	Whether the container needs to be rebuilt the next time it is initialized.
DrupalKernel::$defaultBootstrapContainerDefinition	protected	property	Holds the default bootstrap container definition.
DrupalKernel::$environment	protected	property	The environment, e.g. 'testing', 'install'.
DrupalKernel::$isEnvironmentInitialized	protected static	property	Whether the PHP environment has been initialized.
DrupalKernel::$moduleData	protected	property	List of available modules and installation profiles.
DrupalKernel::$moduleList	protected	property	Holds the list of enabled modules.
DrupalKernel::$phpArrayDumperClass	protected	property	Holds the class used for dumping the container to a PHP array.
DrupalKernel::$prepared	protected	property	Whether essential services have been set up properly by preHandle().
DrupalKernel::$root	protected	property	The app root.
DrupalKernel::$serviceProviderClasses	protected	property	List of discovered service provider class names or objects.
DrupalKernel::$serviceProviders	protected	property	List of instantiated service provider classes.
DrupalKernel::$serviceYamls	protected	property	List of discovered services.yml pathnames.
DrupalKernel::$sitePath	protected	property	The site directory.
DrupalKernel::addServiceFiles	protected	function	Add service files.
DrupalKernel::attachSynthetic	protected	function	Attach synthetic values on to kernel.
DrupalKernel::boot	public	function	Boots the current kernel. Overrides DrupalKernelInterface::boot	1
DrupalKernel::bootEnvironment	public static	function	Setup a consistent PHP environment.
DrupalKernel::cacheDrupalContainer	protected	function	Stores the container definition in a cache.	1
DrupalKernel::classLoaderAddMultiplePsr4	protected	function	Registers a list of namespaces with PSR-4 directories for class loading.
DrupalKernel::compileContainer	protected	function	Compiles a new service container.
DrupalKernel::createFromRequest	public static	function	Create a DrupalKernel object from a request.	1
DrupalKernel::discoverServiceProviders	public	function	Discovers available serviceProviders. Overrides DrupalKernelInterface::discoverServiceProviders	2
DrupalKernel::findSitePath	public static	function	Returns the appropriate site directory for a request.
DrupalKernel::getAppRoot	public	function	Gets the app root. Overrides DrupalKernelInterface::getAppRoot
DrupalKernel::getCachedContainerDefinition	public	function	Returns the cached container definition - if any. Overrides DrupalKernelInterface::getCachedContainerDefinition
DrupalKernel::getConfigStorage	protected	function	Returns the active configuration storage to use during building the container.	1
DrupalKernel::getContainer	public	function	Gets the current container. Overrides DrupalKernelInterface::getContainer
DrupalKernel::getContainerBuilder	protected	function	Gets a new ContainerBuilder instance used to build the service container.
DrupalKernel::getContainerCacheKey	protected	function	Returns the container cache key based on the environment.
DrupalKernel::getHttpKernel	protected	function	Gets a http kernel from the container
DrupalKernel::getInstallProfile	protected	function	Gets the active install profile.	1
DrupalKernel::getKernelParameters	protected	function	Returns the kernel parameters.
DrupalKernel::getModuleFileNames	protected	function	Gets the file name for each enabled module.
DrupalKernel::getModuleNamespacesPsr4	protected	function	Gets the PSR-4 base directories for module namespaces.
DrupalKernel::getModulesParameter	protected	function	Returns an array of Extension class parameters for all enabled modules.
DrupalKernel::getServiceProviders	public	function	Returns all registered service providers. Overrides DrupalKernelInterface::getServiceProviders
DrupalKernel::getServicesToPersist	protected	function	Returns service instances to persist from an old container to a new one.
DrupalKernel::getSitePath	public	function	Get the site path. Overrides DrupalKernelInterface::getSitePath
DrupalKernel::guessApplicationRoot	protected static	function	Determine the application root directory based on this file's location.
DrupalKernel::handle	public	function	Handles a Request to convert it to a Response.	1
DrupalKernel::handleException	protected	function	Converts an exception into a response.
DrupalKernel::initializeContainer	protected	function	Initializes the service container.	2
DrupalKernel::initializeRequestGlobals	protected	function	Bootstraps the legacy global request variables.
DrupalKernel::initializeServiceProviders	protected	function	Registers all service providers to the kernel.
DrupalKernel::initializeSettings	protected	function	Locate site path and initialize settings singleton.
DrupalKernel::invalidateContainer	public	function	Invalidate the service container for the next request. Overrides DrupalKernelInterface::invalidateContainer
DrupalKernel::loadLegacyIncludes	public	function	Helper method that loads legacy Drupal include files. Overrides DrupalKernelInterface::loadLegacyIncludes	1
DrupalKernel::moduleData	protected	function	Returns module data on the filesystem.
DrupalKernel::persistServices	protected	function	Moves persistent service instances into a new container.
DrupalKernel::preHandle	public	function	Helper method that does request related initialization. Overrides DrupalKernelInterface::preHandle
DrupalKernel::prepareLegacyRequest	public	function	Prepare the kernel for handling a request without handling the request. Overrides DrupalKernelInterface::prepareLegacyRequest
DrupalKernel::rebuildContainer	public	function	Force a container rebuild. Overrides DrupalKernelInterface::rebuildContainer
DrupalKernel::setContainer	public	function	Sets the Container.
DrupalKernel::setSitePath	public	function	Set the current site path. Overrides DrupalKernelInterface::setSitePath
DrupalKernel::setupTrustedHosts	protected static	function	Sets up the lists of trusted HTTP Host headers.
DrupalKernel::shutdown	public	function	Shuts down the kernel. Overrides DrupalKernelInterface::shutdown
DrupalKernel::terminate	public	function	Terminates a request/response cycle.
DrupalKernel::updateModules	public	function	Implements Drupal\Core\DrupalKernelInterface::updateModules(). Overrides DrupalKernelInterface::updateModules
DrupalKernel::validateHostname	public static	function	Validates the hostname supplied from the HTTP request.
DrupalKernel::validateHostnameLength	protected static	function	Validates a hostname length.
DrupalKernel::__construct	public	function	Constructs a DrupalKernel object.	2
DrupalKernelInterface::CONTAINER_INITIALIZE_SUBREQUEST_FINISHED		constant	Event fired when the service container finished initializing in subrequest.
InstallerRedirectTrait::isCli	protected	function	Returns whether the current PHP process runs on CLI.
InstallerRedirectTrait::shouldRedirectToInstaller	protected	function	Determines if an exception handler should redirect to the installer.

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class DrupalKernel in Drupal 8

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