feat: added Redis-ready session scaling

.docker/apache/Dockerfile

@@ -1,12 +1,12 @@
 #
-# This image uses a php:8.4-apache base image and do not have any phpMyFAQ code with it.
+# This image uses a php:8.5-apache base image and do not have any phpMyFAQ code with it.
 # It's for development only, it's meant to be run with docker-compose
 #
 
 #####################################
 #=== Unique stage without payload ===
 #####################################
-FROM php:8.4-apache
+FROM php:8.5-apache
 
 #=== Install gd PHP dependencie ===
 RUN set -x \
@@ -61,6 +61,10 @@ RUN set -ex \
 RUN pecl install xdebug-3.5.0  \
 && docker-php-ext-enable xdebug
 
+#=== Install redis PHP extension ===
+RUN pecl install redis-6.3.0 \
+ && docker-php-ext-enable redis
+
 #=== php default ===
 ENV PMF_TIMEZONE="Europe/Berlin" \
     PMF_ENABLE_UPLOADS=On \

.docker/frankenphp/Dockerfile

@@ -41,6 +41,10 @@ RUN docker-php-ext-configure gd --with-freetype --with-jpeg \
  RUN pecl install xdebug \
      && docker-php-ext-enable xdebug
 
+#=== Install redis PHP extension ===
+RUN pecl install redis \
+    && docker-php-ext-enable redis
+
 #=== Environment variables ===
 ENV PMF_TIMEZONE="Europe/Berlin" \
     PMF_ENABLE_UPLOADS=On \

.docker/php-fpm/Dockerfile

@@ -1,12 +1,12 @@
 #
-# This image uses a php:8.4-fpm base image and does not have any phpMyFAQ code with it.
+# This image uses a php:8.5-fpm base image and does not have any phpMyFAQ code with it.
 # It's for development only, it's meant to be run with docker-compose
 #
 
 #####################################
 #=== Unique stage without payload ===
 #####################################
-FROM php:8.4-fpm
+FROM php:8.5-fpm
 
 #=== Install gd PHP dependencies ===
 RUN set -x \
@@ -61,6 +61,10 @@ RUN set -ex \
 RUN pecl install xdebug-3.5.0 \
 && docker-php-ext-enable xdebug
 
+#=== Install redis PHP extension ===
+RUN pecl install redis \
+ && docker-php-ext-enable redis
+
 #=== php default ===
 ENV PMF_TIMEZONE="Europe/Berlin" \
     PMF_ENABLE_UPLOADS=On \

README.md

@@ -33,7 +33,7 @@ and can be run on almost any web hosting provider or deployed in the cloud using
 
 ## Requirements
 
-phpMyFAQ is only supported on PHP 8.3 and up, you need a database as well. Supported databases are MySQL, MariaDB,
+phpMyFAQ is only supported on PHP 8.4+, you need a database as well. Supported databases are MySQL, MariaDB,
 Percona Server, PostgreSQL, Microsoft SQL Server, and SQLite3. If you want to use Elasticsearch or Opensearch as the 
 main search engine, you need Elasticsearch v6+ or OpenSearch v1+. Check our detailed requirements on
 [phpmyfaq.de](https://www.phpmyfaq.de/requirements) for more information.
@@ -75,17 +75,18 @@ _Running using named volumes:_
 - **sqlserver**: image with Microsoft SQL Server for Linux
 - **elasticsearch**: Open Source Software image (it means it does not have XPack installed)
 - **opensearch**: OpenSearch image (it means it does not have XPack installed)
+- **redis**: image with a Redis database
 
-_Running apache web server with PHP 8.4 support:_
+_Running apache web server with PHP 8.5 support:_
 
 - **apache**: mounts the `phpmyfaq` folder in place of `/var/www/html`.
 
-_Running nginx web server with PHP 8.4 support:_
+_Running nginx web server with PHP 8.5 support:_
 
 - **nginx**: mounts the `phpmyfaq` folder in place of `/var/www/html`.
-- **php-fpm**: PHP-FPM image with PHP 8.4 support
+- **php-fpm**: PHP-FPM image with PHP 8.5 support
 
-_Running FrankenPHP web server with PHP 8.4 support:_
+_Running FrankenPHP web server with PHP 8.5 support:_
 
 - **frankenphp**: mounts the `phpmyfaq` folder in place of `/var/www/html`.
 

docker-compose.yml

@@ -28,6 +28,15 @@ services:
     volumes:
       - ./volumes/postgres:/var/lib/postgresql/data
 
+  redis:
+    image: redis:7-alpine
+    restart: always
+    command: redis-server --appendonly yes
+    ports:
+      - '6379:6379'
+    volumes:
+      - ./volumes/redis:/data
+
   #sqlserver:
   #  image: mcr.microsoft.com/mssql/server:2022-latest
   #  ports:
@@ -60,6 +69,7 @@ services:
     links:
       - mariadb:db
       - postgres
+      - redis
       - elasticsearch
       - opensearch
     ports:
@@ -107,6 +117,7 @@ services:
     links:
       - mariadb:db
       - postgres
+      - redis
       - elasticsearch
       - opensearch
     volumes:
@@ -136,6 +147,7 @@ services:
     links:
       - mariadb:db
       - postgres
+      - redis
       - elasticsearch
       - opensearch
     ports:

docs/installation.md

@@ -67,6 +67,10 @@ The PDO extension is the preferred way to connect to your database server.
 - [Elasticsearch](https://www.elastic.co/products/elasticsearch) 7.x or 8.x
 - [OpenSearch](https://opensearch.org/) 2.x
 
+### Optional In-Memory Data Store
+
+- [Redis](https://redis.io/) 8.x or later
+
 ### Additional requirements
 
 - correctly set: access permissions, owner, group

phpmyfaq/src/phpMyFAQ/Bootstrap/PhpConfigurator.php

@@ -19,6 +19,10 @@
 
 namespace phpMyFAQ\Bootstrap;
 
+use phpMyFAQ\Configuration;
+use phpMyFAQ\Session\RedisSessionHandler;
+use RuntimeException;
+
 class PhpConfigurator
 {
     /**
@@ -53,7 +57,7 @@ public static function registerErrorHandlers(): void
     /**
      * Configures secure session settings if no session is active yet.
      */
-    public static function configureSession(): void
+    public static function configureSession(?Configuration $configuration = null): void
     {
         if (session_status() !== PHP_SESSION_ACTIVE) {
             ini_set('session.use_only_cookies', value: '1');
@@ -65,6 +69,23 @@ public static function configureSession(): void
             if (defined('PMF_SESSION_SAVE_PATH') && PMF_SESSION_SAVE_PATH !== '') {
                 ini_set('session.save_path', value: PMF_SESSION_SAVE_PATH);
             }
+
+            $sessionHandler = strtolower((string) ($configuration?->get('session.handler') ?? 'files'));
+            $redisDsn = trim((string) ($configuration?->get('session.redisDsn') ?? ''));
+
+            switch ($sessionHandler) {
+                case 'files':
+                    ini_set('session.save_handler', value: 'files');
+                    break;
+                case 'redis':
+                    RedisSessionHandler::configure($redisDsn);
+                    break;
+                default:
+                    throw new RuntimeException(sprintf(
+                        'Unsupported session handler "%s". Allowed values: files, redis.',
+                        $sessionHandler,
+                    ));
+            }
         }
     }
 }

phpmyfaq/src/phpMyFAQ/Bootstrapper.php

@@ -85,7 +85,7 @@ public function run(): self
             $this->connectDatabase($databaseFile);
 
             // 12. Session configuration
-            PhpConfigurator::configureSession();
+            PhpConfigurator::configureSession($this->faqConfig);
 
             // 13. LDAP
             $this->configureLdap();

phpmyfaq/src/phpMyFAQ/Session/RedisSessionHandler.php

@@ -0,0 +1,97 @@
+<?php
+
+/**
+ * Configures native PHP Redis-backed sessions with connectivity checks.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public License,
+ * v. 2.0. If a copy of the MPL was not distributed with this file, You can
+ * obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * @package   phpMyFAQ
+ * @author    Thorsten Rinne <thorsten@phpmyfaq.de>
+ * @copyright 2026 phpMyFAQ Team
+ * @license   https://www.mozilla.org/MPL/2.0/ Mozilla Public License Version 2.0
+ * @link      https://www.phpmyfaq.de
+ * @since     2026-02-14
+ */
+
+declare(strict_types=1);
+
+namespace phpMyFAQ\Session;
+
+use RuntimeException;
+
+class RedisSessionHandler
+{
+    public const string DEFAULT_DSN = 'tcp://redis:6379?database=0';
+
+    public static function configure(string $dsn = '', bool $validate = false): void
+    {
+        if (!extension_loaded('redis')) {
+            throw new RuntimeException('Redis session handler requires the PHP redis extension (ext-redis).');
+        }
+
+        $redisDsn = trim($dsn) !== '' ? trim($dsn) : self::DEFAULT_DSN;
+
+        if ($validate) {
+            self::validateConnection($redisDsn);
+        }
+
+        ini_set('session.save_handler', value: 'redis');
+        ini_set('session.save_path', value: $redisDsn);
+    }
+
+    public static function validateConnection(string $dsn, float $timeoutSeconds = 1.0): void
+    {
+        [$socketTarget, $displayTarget] = self::buildSocketTarget($dsn);
+
+        $errno = 0;
+        $errorString = '';
+        $connection = @stream_socket_client(
+            $socketTarget,
+            $errno,
+            $errorString,
+            $timeoutSeconds,
+            STREAM_CLIENT_CONNECT,
+        );
+
+        if ($connection === false) {
+            throw new RuntimeException(sprintf(
+                'Redis session handler is configured but unreachable (%s): %s',
+                $displayTarget,
+                $errorString !== '' ? $errorString : 'connection failed',
+            ));
+        }
+
+        fclose($connection);
+    }
+
+    /**
+     * @return array{0: string, 1: string}
+     */
+    private static function buildSocketTarget(string $dsn): array
+    {
+        $parsedUrl = parse_url($dsn);
+        if ($parsedUrl === false || !isset($parsedUrl['scheme'])) {
+            throw new RuntimeException('Invalid Redis DSN for sessions.');
+        }
+
+        $scheme = strtolower((string) $parsedUrl['scheme']);
+        if ($scheme === 'redis' || $scheme === 'tcp') {
+            $host = $parsedUrl['host'] ?? '127.0.0.1';
+            $port = (int) ($parsedUrl['port'] ?? 6379);
+            return [sprintf('tcp://%s:%d', $host, $port), sprintf('%s:%d', $host, $port)];
+        }
+
+        if ($scheme === 'unix') {
+            $path = $parsedUrl['path'] ?? '';
+            if ($path === '') {
+                throw new RuntimeException('Invalid Redis unix socket DSN for sessions.');
+            }
+
+            return ['unix://' . $path, $path];
+        }
+
+        throw new RuntimeException(sprintf('Unsupported Redis DSN scheme "%s" for sessions.', $scheme));
+    }
+}

phpmyfaq/src/phpMyFAQ/Setup/Installation/DefaultDataSeeder.php

@@ -285,6 +285,8 @@ private static function buildDefaultConfig(): array
             'api.onlyPublicQuestions' => 'true',
             'api.ignoreOrphanedFaqs' => 'true',
             'queue.transport' => 'database',
+            'session.handler' => 'files',
+            'session.redisDsn' => 'tcp://redis:6379?database=0',
             'upgrade.dateLastChecked' => '',
             'upgrade.lastDownloadedPackage' => '',
             'upgrade.onlineUpdateEnabled' => 'false',

phpmyfaq/src/phpMyFAQ/Setup/Migration/Versions/Migration420Alpha.php

@@ -210,6 +210,8 @@ public function up(OperationRecorder $recorder): void
         $recorder->addConfig('api.rateLimit.requests', '100');
         $recorder->addConfig('api.rateLimit.interval', '3600');
         $recorder->addConfig('queue.transport', 'database');
+        $recorder->addConfig('session.handler', 'files');
+        $recorder->addConfig('session.redisDsn', 'tcp://redis:6379?database=0');
         $recorder->addConfig('mail.useQueue', 'true');
         $recorder->addConfig('mail.provider', 'smtp');
         $recorder->addConfig('mail.sendgridApiKey', '');