Issue #3103529 by alexpott, mcdruid, Chris Burge, greg.1.anderson, rf…

…ay, catch, anavarre, Gábor Hojtsy, jungle: Drupal 8.8.1+ and 9 can fail to install in the web browser due to cache pollution

lib/Drupal/Core/DrupalKernel.php

@@ -621,6 +621,20 @@ public function discoverServiceProviders() {
     // 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();

modules/simpletest/src/KernelTestBase.php

@@ -216,6 +216,9 @@ protected function setUp() {
     if (file_exists($directory . '/settings.testing.php')) {
       Settings::initialize(DRUPAL_ROOT, $site_path, $class_loader);
     }
+    // Set the module list upfront to avoid setting the kernel into the
+    // pre-installer mode.
+    $this->kernel->updateModules([], []);
     $this->kernel->boot();
 
     // Ensure database install tasks have been run.
@@ -231,6 +234,9 @@ protected function setUp() {
     // prevents any services created during the first boot from having stale
     // database connections, for example, \Drupal\Core\Config\DatabaseStorage.
     $this->kernel->shutdown();
+    // Set the module list upfront to avoid setting the kernel into the
+    // pre-installer mode.
+    $this->kernel->updateModules([], []);
     $this->kernel->boot();
 
     // Save the original site directory path, so that extensions in the

tests/Drupal/FunctionalTests/Installer/InstallerExistingSettingsTest.php

@@ -54,6 +54,17 @@ protected function prepareEnvironment() {
     mkdir($this->settings['settings']['config_sync_directory']->value, 0777, TRUE);
   }
 
+  /**
+   * Visits the interactive installer.
+   */
+  protected function visitInstaller() {
+    // Should redirect to the installer.
+    $this->drupalGet($GLOBALS['base_url']);
+    // Ensure no database tables have been created yet.
+    $this->assertSame([], Database::getConnection()->schema()->findTables('%'));
+    $this->assertSession()->addressEquals($GLOBALS['base_url'] . '/core/install.php');
+  }
+
   /**
    * {@inheritdoc}
    */

tests/Drupal/KernelTests/KernelTestBase.php

@@ -348,11 +348,12 @@ private function bootKernel() {
     // Bootstrap the kernel. Do not use createFromRequest() to retain Settings.
     $kernel = new DrupalKernel('testing', $this->classLoader, FALSE);
     $kernel->setSitePath($this->siteDirectory);
-    // Boot a new one-time container from scratch. Ensure to set the module list
-    // upfront to avoid a subsequent rebuild.
-    if ($modules && $extensions = $this->getExtensionsForModules($modules)) {
-      $kernel->updateModules($extensions, $extensions);
-    }
+    // Boot a new one-time container from scratch. Set the module list upfront
+    // to avoid a subsequent rebuild or setting the kernel into the
+    // pre-installer mode.
+    $extensions = $modules ? $this->getExtensionsForModules($modules) : [];
+    $kernel->updateModules($extensions, $extensions);
+
     // DrupalKernel::boot() is not sufficient as it does not invoke preHandle(),
     // which is required to initialize legacy global variables.
     $request = Request::create('/');