[HttpKernel] Prevent search engines from indexing dev applications

Author: GaryPEGEOT

DependencyInjection/Configuration.php

@@ -108,6 +108,7 @@ public function getConfigTreeBuilder()
         $this->addWebLinkSection($rootNode);
         $this->addLockSection($rootNode);
         $this->addMessengerSection($rootNode);
+        $this->addRobotsIndexSection($rootNode);
 
         return $treeBuilder;
     }
@@ -1156,4 +1157,17 @@ function ($a) {
             ->end()
         ;
     }
+
+    private function addRobotsIndexSection(ArrayNodeDefinition $rootNode)
+    {
+        $rootNode
+            ->children()
+                ->booleanNode('disallow_search_engine_index')
+                    ->info('Enabled by default when debug is enabled.')
+                    ->defaultValue($this->debug)
+                    ->treatNullLike($this->debug)
+                ->end()
+            ->end()
+        ;
+    }
 }

DependencyInjection/FrameworkExtension.php

@@ -394,6 +394,10 @@ public function load(array $configs, ContainerBuilder $container)
             // remove tagged iterator argument for resource checkers
             $container->getDefinition('config_cache_factory')->setArguments([]);
         }
+
+        if (!$config['disallow_search_engine_index'] ?? false) {
+            $container->removeDefinition('disallow_search_engine_index_response_listener');
+        }
     }
 
     /**

Resources/config/web.xml

@@ -85,5 +85,8 @@
             <argument type="service" id="controller_name_converter" />
             <tag name="kernel.event_subscriber" />
         </service>
+        <service id="disallow_search_engine_index_response_listener" class="Symfony\Component\HttpKernel\EventListener\DisallowRobotsIndexingListener">
+            <tag name="kernel.event_subscriber" />
+        </service>
     </services>
 </container>

Tests/DependencyInjection/ConfigurationTest.php

@@ -330,6 +330,7 @@ class_exists(SemaphoreStore::class) && SemaphoreStore::isSupported() ? 'semaphor
                 'default_bus' => null,
                 'buses' => ['messenger.bus.default' => ['default_middleware' => true, 'middleware' => []]],
             ],
+            'disallow_search_engine_index' => true,
         ];
     }
 }

Tests/DependencyInjection/FrameworkExtensionTest.php

@@ -1327,6 +1327,27 @@ public function testSessionCookieSecureAuto()
         $this->assertEquals($expected, array_keys($container->getDefinition('session_listener')->getArgument(0)->getValues()));
     }
 
+    public function testRobotsTagListenerIsRegisteredInDebugMode()
+    {
+        $container = $this->createContainer(['kernel.debug' => true]);
+        (new FrameworkExtension())->load([], $container);
+        $this->assertTrue($container->has('disallow_search_engine_index_response_listener'), 'DisallowRobotsIndexingListener should be registered');
+
+        $definition = $container->getDefinition('disallow_search_engine_index_response_listener');
+        $this->assertTrue($definition->hasTag('kernel.event_subscriber'), 'DisallowRobotsIndexingListener should have the correct tag');
+
+        $container = $this->createContainer(['kernel.debug' => true]);
+        (new FrameworkExtension())->load([['disallow_search_engine_index' => false]], $container);
+        $this->assertFalse(
+            $container->has('disallow_search_engine_index_response_listener'),
+            'DisallowRobotsIndexingListener should not be registered when explicitly disabled'
+        );
+
+        $container = $this->createContainer(['kernel.debug' => false]);
+        (new FrameworkExtension())->load([], $container);
+        $this->assertFalse($container->has('disallow_search_engine_index_response_listener'), 'DisallowRobotsIndexingListener should NOT be registered');
+    }
+
     protected function createContainer(array $data = [])
     {
         return new ContainerBuilder(new ParameterBag(array_merge([