diff --git a/automatic_updates.services.yml b/automatic_updates.services.yml
index 26d646a..0d335fc 100644
--- a/automatic_updates.services.yml
+++ b/automatic_updates.services.yml
@@ -2,6 +2,10 @@ services:
   logger.channel.automatic_updates:
     parent: logger.channel_base
     arguments: ['automatic_updates']
+  automatic_updates.drupal_finder:
+    class: DrupalFinder\DrupalFinder
+  automatic_updates.filesystem_cache:
+    class: League\Flysystem\Cached\Storage\Memory
   automatic_updates.psa:
     class: Drupal\automatic_updates\Services\AutomaticUpdatesPsa
     arguments:
@@ -13,3 +17,6 @@ services:
       - '@extension.list.profile'
       - '@extension.list.theme'
       - '@logger.channel.automatic_updates'
+  plugin.manager.preflight:
+    class: Drupal\automatic_updates\PreflightPluginManager
+    parent: default_plugin_manager
diff --git a/composer.json b/composer.json
index 0e18c77..e366d15 100644
--- a/composer.json
+++ b/composer.json
@@ -12,6 +12,9 @@
   },
   "require": {
     "ext-json": "*",
-    "composer/semver": "^1.0@dev"
+    "composer/semver": "^1.0",
+    "league/flysystem": "^1.1",
+    "league/flysystem-cached-adapter": "^1.0",
+    "webflo/drupal-finder": "^1.1"
   }
 }
diff --git a/src/Annotation/Preflight.php b/src/Annotation/Preflight.php
new file mode 100644
index 0000000..6efe017
--- /dev/null
+++ b/src/Annotation/Preflight.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace Drupal\automatic_updates\Annotation;
+
+use Drupal\Component\Annotation\Plugin;
+
+/**
+ * Defines preflight annotation object.
+ *
+ * @Annotation
+ */
+class Preflight extends Plugin {
+
+  /**
+   * The plugin ID.
+   *
+   * @var string
+   */
+  public $id;
+
+  /**
+   * The human-readable name of the plugin.
+   *
+   * @var \Drupal\Core\Annotation\Translation
+   *
+   * @ingroup plugin_translatable
+   */
+  public $title;
+
+  /**
+   * The description of the plugin.
+   *
+   * @var \Drupal\Core\Annotation\Translation
+   *
+   * @ingroup plugin_translatable
+   */
+  public $description;
+
+}
diff --git a/src/Plugin/Preflight/FilesystemPreflight.php b/src/Plugin/Preflight/FilesystemPreflight.php
new file mode 100644
index 0000000..1cb83d0
--- /dev/null
+++ b/src/Plugin/Preflight/FilesystemPreflight.php
@@ -0,0 +1,156 @@
+<?php
+
+namespace Drupal\automatic_updates\Plugin\Preflight;
+
+use Drupal\automatic_updates\PreflightPluginBase;
+use Drupal\Component\Render\MarkupInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+use DrupalFinder\DrupalFinder;
+use League\Flysystem\Adapter\Local;
+use League\Flysystem\Cached\CachedAdapter;
+use League\Flysystem\Cached\CacheInterface;
+use League\Flysystem\FileExistsException;
+use League\Flysystem\FileNotFoundException;
+use League\Flysystem\Filesystem;
+use League\Flysystem\FilesystemInterface;
+use Psr\Log\LoggerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Plugin implementation of the preflight.
+ *
+ * @Preflight(
+ *   id = "filesystem_preflight",
+ *   label = @Translation("Preflight for filesystem"),
+ *   description = @Translation("Does preflight checks for checking if the file system is ready for update..")
+ * )
+ */
+class FilesystemPreflight extends PreflightPluginBase implements ContainerFactoryPluginInterface {
+  use StringTranslationTrait;
+
+  /**
+   * The logger.
+   *
+   * @var \Psr\Log\LoggerInterface
+   */
+  protected $logger;
+
+  /**
+   * The core file system.
+   *
+   * @var \League\Flysystem\FilesystemInterface
+   */
+  protected $coreFileSystem;
+
+  /**
+   * The vendor file system.
+   *
+   * @var \League\Flysystem\FilesystemInterface
+   */
+  protected $vendorFileSystem;
+
+  /**
+   * AutomaticUpdatesPreflight constructor.
+   *
+   * @param \DrupalFinder\DrupalFinder $drupal_finder
+   *   The drupal finder service.
+   * @param \League\Flysystem\Cached\CacheInterface $file_system_cache
+   *   The file system cache.
+   * @param \Psr\Log\LoggerInterface $logger
+   *   The logger.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, DrupalFinder $drupal_finder, CacheInterface $file_system_cache, LoggerInterface $logger) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->logger = $logger;
+    $this->findDrupal($drupal_finder, $file_system_cache);
+  }
+
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('automatic_updates.drupal_finder'),
+      $container->get('automatic_updates.filesystem_cache'),
+      $container->get('logger.channel.automatic_updates')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function runPreflight() {
+    $messages = [];
+    if (!$this->coreFileSystem || !$this->coreFileSystem->has('COPYRIGHT.txt')) {
+      $messages[] = $this->t('The drupal web public directory could not be located.');
+      return $messages;
+    }
+    $this->readOnly($messages);
+    return $messages;
+  }
+
+  /**
+   * Find where drupal is located.
+   *
+   * @param \DrupalFinder\DrupalFinder $drupal_finder
+   *   The drupal finder service.
+   * @param \League\Flysystem\Cached\CacheInterface $file_system_cache
+   *   The file system cache.
+   */
+  protected function findDrupal(DrupalFinder $drupal_finder, CacheInterface $file_system_cache) {
+    if ($drupal_finder->locateRoot(getcwd())) {
+      $this->coreFileSystem = new Filesystem(new CachedAdapter(new Local($drupal_finder->getDrupalRoot() . '/core'), $file_system_cache));
+      $this->vendorFileSystem = new Filesystem(new CachedAdapter(new Local($drupal_finder->getVendorDir()), $file_system_cache));
+    }
+  }
+
+  /**
+   * Check if the filesystem is read only.
+   *
+   * @param array $messages
+   *   The messages array of translatable strings.
+   */
+  protected function readOnly(array &$messages) {
+    try {
+      $this->doReadOnlyCheck($this->coreFileSystem, 'COPYRIGHT.txt', $messages, $this->t('Drupal core filesystem is read only.'));
+      $this->doReadOnlyCheck($this->vendorFileSystem, 'composer/LICENSE', $messages, $this->t('Vendor filesystem is read only.'));
+    }
+    catch (\LogicException $exception) {
+      $this->logger->error($exception->getMessage());
+      $messages[] = $this->t('During read only check, a logic exception was encountered');
+    }
+  }
+
+  /**
+   * Do the read only check.
+   *
+   * @param \League\Flysystem\FilesystemInterface $filesystem
+   *   The filesystem to test.
+   * @param string $file
+   *   The file path.
+   * @param array $messages
+   *   The messages array of translatable strings.
+   * @param \Drupal\Component\Render\MarkupInterface $message
+   *   The error message to add if the file is read only.
+   */
+  private function doReadOnlyCheck(FilesystemInterface $filesystem, $file, array &$messages, MarkupInterface $message) {
+    try {
+      if ($filesystem->rename($file, "$file.moved")) {
+        // Move it back after moving it.
+        $filesystem->rename("$file.moved", $file);
+      }
+      else {
+        $messages[] = $message;
+      }
+    }
+    catch (FileExistsException $exception) {
+      $this->logger->error($exception->getMessage());
+      $messages[] = $this->t('File already exists at path: %file', ['%file' => $exception->getPath()]);
+    }
+    catch (FileNotFoundException $exception) {
+      $this->logger->error($exception->getMessage());
+      $messages[] = $this->t('File not found at path: %file', ['%file' => $exception->getPath()]);
+    }
+  }
+}
diff --git a/src/PreflightPluginBase.php b/src/PreflightPluginBase.php
new file mode 100644
index 0000000..db38fcd
--- /dev/null
+++ b/src/PreflightPluginBase.php
@@ -0,0 +1,11 @@
+<?php
+
+namespace Drupal\automatic_updates;
+
+use Drupal\Component\Plugin\PluginBase;
+
+/**
+ * Base class for preflight plugins.
+ */
+abstract class PreflightPluginBase extends PluginBase implements PreflightInterface {
+}
diff --git a/src/PreflightPluginManager.php b/src/PreflightPluginManager.php
new file mode 100644
index 0000000..0730d61
--- /dev/null
+++ b/src/PreflightPluginManager.php
@@ -0,0 +1,37 @@
+<?php
+
+namespace Drupal\automatic_updates;
+
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Plugin\DefaultPluginManager;
+
+/**
+ * Preflight plugin manager.
+ */
+class PreflightPluginManager extends DefaultPluginManager {
+
+  /**
+   * Constructs PreflightPluginManager object.
+   *
+   * @param \Traversable $namespaces
+   *   An object that implements \Traversable which contains the root paths
+   *   keyed by the corresponding namespace to look for plugin implementations.
+   * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
+   *   Cache backend instance to use.
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
+   *   The module handler to invoke the alter hook with.
+   */
+  public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
+    parent::__construct(
+      'Plugin/Preflight',
+      $namespaces,
+      $module_handler,
+      'Drupal\automatic_updates\PreflightInterface',
+      'Drupal\automatic_updates\Annotation\Preflight'
+    );
+    $this->alterInfo('preflight_info');
+    $this->setCacheBackend($cache_backend, 'preflight_plugins');
+  }
+
+}
diff --git a/tests/src/Kernel/AutomaticUpdatesPreflightTest.php b/tests/src/Kernel/AutomaticUpdatesPreflightTest.php
new file mode 100644
index 0000000..9241d54
--- /dev/null
+++ b/tests/src/Kernel/AutomaticUpdatesPreflightTest.php
@@ -0,0 +1,30 @@
+<?php
+
+namespace Drupal\Tests\automatic_updates\Kernel;
+
+use Drupal\KernelTests\KernelTestBase;
+
+/**
+ * Tests automatic updates preflight checking.
+ *
+ * @group automatic_updates
+ */
+class AutomaticUpdatesPreflightTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['automatic_updates'];
+
+  /**
+   * Tests the functionality of test actions.
+   */
+  public function testReadOnly() {
+    /** @var \Drupal\automatic_updates\PreflightPluginManager $manager */
+    $manager = $this->container->get('plugin.manager.preflight');
+    /** @var \Drupal\automatic_updates\Plugin\Preflight\FilesystemPreflight $plugin */
+    $plugin = $manager->createInstance('filesystem_preflight');
+    $this->assertEmpty($plugin->runPreflight());
+  }
+
+}