Log every time a session is created

Prior to this change there we weren't able to keep track of sessions that got lost.

This change allows us to see every time a session is created and distinguish them by their correlation id.

src/Service/SessionCorrelationIdService.php

@@ -0,0 +1,44 @@
+<?php
+
+/**
+ * Copyright 2024 SURFnet B.V.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+declare(strict_types = 1);
+
+namespace Surfnet\Tiqr\Service;
+
+use Symfony\Component\HttpFoundation\RequestStack;
+
+final readonly class SessionCorrelationIdService
+{
+    private const SALT = 'Mr6LpJYtuWRDdVR2_7VgTChFhzQ';
+
+    public function __construct(
+        private RequestStack $requestStack
+    ) {
+    }
+
+    public function generateCorrelationId(): ?string
+    {
+        $sessionCookie = $this->requestStack->getMainRequest()?->cookies->get('PHPSESSID');
+
+        if ($sessionCookie === null) {
+            return null;
+        }
+
+        return hash('sha256', self::SALT . substr($sessionCookie, 10));
+    }
+}

src/Session/LoggingSessionFactory.php

@@ -0,0 +1,70 @@
+<?php
+
+declare(strict_types = 1);
+
+/**
+ * Copyright 2024 SURFnet B.V.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Surfnet\Tiqr\Session;
+
+use Psr\Log\LoggerInterface;
+use Surfnet\Tiqr\Service\SessionCorrelationIdService;
+use Surfnet\Tiqr\WithContextLogger;
+use Symfony\Component\DependencyInjection\Attribute\AsDecorator;
+use Symfony\Component\DependencyInjection\Attribute\Autowire;
+use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Component\HttpFoundation\Session\SessionFactory;
+use Symfony\Component\HttpFoundation\Session\SessionInterface;
+use Symfony\Component\HttpFoundation\Session\Storage\SessionStorageFactoryInterface;
+
+/**
+ * This class serves as a decorated version of Symfony's SessionFactory class.
+ * Every time a session is created, we'll add a log entry that can be identified by the correlation id.
+ *
+ * For this logging function to work we need a stateless logger, therefore we inject the default logger by using the variable name $monoLogger.
+ * The variable name $logger has been bound to the Surfnet GSSP logger in the Symfony container, so we'll need to use another variable name.
+ * The Surfnet GSSP Logger isn't stateless as it's dependent on the current session, which has not been created when the logging occurs.
+ *
+ * @see SessionFactory::createSession()
+ */
+#[AsDecorator('session.factory')]
+final class LoggingSessionFactory extends SessionFactory
+{
+    private LoggerInterface $logger;
+
+    public function __construct(
+        RequestStack                   $requestStack,
+        #[Autowire(service: 'session.storage.factory')]
+        SessionStorageFactoryInterface $storageFactory,
+        LoggerInterface                $monologLogger,
+        SessionCorrelationIdService    $sessionCorrelationIdService,
+        ?callable                      $usageReporter = null,
+    ) {
+        $this->logger = WithContextLogger::from(
+            $monologLogger,
+            ['correlationId' => $sessionCorrelationIdService->generateCorrelationId() ?? ''],
+        );
+
+        parent::__construct($requestStack, $storageFactory, $usageReporter);
+    }
+
+    public function createSession(): SessionInterface
+    {
+        $this->logger->info('Created new session.');
+
+        return parent::createSession();
+    }
+}