Add page about configuring the session TTL

Author: Seldaek

session.rst

@@ -192,5 +192,6 @@ More about Sessions
     session/locale_sticky_session
     session/php_bridge
     session/proxy_examples
+    session/configuring_ttl
 
 .. _`HttpFoundation component`: https://symfony.com/components/HttpFoundation

session/configuring_ttl.rst

@@ -0,0 +1,121 @@
+.. index::
+    single: Sessions, defining TTL
+
+Configuring the Session TTL
+===========================
+
+Symfony by default will use PHP's ini setting ``session.gc_maxlifetime`` as
+session lifetime. However if you :doc:`store sessions in a database </session/database>`
+you can also configure your own TTL in the framework configuration or even at runtime.
+
+Changing the ini setting is not possible once the session is started so if you
+want to use a different TTL depending on which user is logged in, you really need
+to do it at runtime using the callback method below.
+
+.. _configuring-the-TTL:
+
+Configuring the TTL
+-------------------
+
+You need to pass the TTL in the options array of the session handler you are using:
+
+.. configuration-block::
+
+    .. code-block:: yaml
+
+        # config/services.yaml
+        services:
+            # ...
+            Symfony\Component\HttpFoundation\Session\Storage\Handler\RedisSessionHandler:
+                arguments:
+                    - '@Redis'
+                    - { 'ttl': 600 }
+
+    .. code-block:: xml
+
+        <!-- config/services.xml -->
+        <services>
+            <service id="Symfony\Component\HttpFoundation\Session\Storage\Handler\RedisSessionHandler">
+                <argument type="service" id="Redis"/>
+                <argument type="collection">
+                    <argument key="ttl">600</argument>
+                </argument>
+            </service>
+        </services>
+
+    .. code-block:: php
+
+        // config/services.php
+        use Symfony\Component\HttpFoundation\Session\Storage\Handler\RedisSessionHandler;
+
+        $services
+            ->set(RedisSessionHandler::class)
+            ->args([
+                service('Redis'),
+                ['ttl' => 600],
+            ]);
+
+.. _configuring-the-TTL-dynamically-at-runtime:
+
+Configuring the TTL dynamically at runtime
+------------------------------------------
+
+If you would like to have a different TTL for different
+users or sessions for whatever reason, this is also possible
+by passing a callback as the TTL value. The callback then has
+to return an integer which will be used as TTL.
+
+The callback will be called right before the session is written.
+
+.. configuration-block::
+
+    .. code-block:: yaml
+
+        # config/services.yaml
+        services:
+            # ...
+            Symfony\Component\HttpFoundation\Session\Storage\Handler\RedisSessionHandler:
+                arguments:
+                    - '@Redis'
+                    - { 'ttl': !closure '@my.ttl.handler' }
+             
+            my.ttl.handler:
+                class: Some\InvokableClass # some class with an __invoke() method
+                arguments:
+                    # Inject whatever dependencies you need to be able to resolve a TTL for the current session
+                    - '@security'
+
+    .. code-block:: xml
+
+        <!-- config/services.xml -->
+        <services>
+            <service id="Symfony\Component\HttpFoundation\Session\Storage\Handler\RedisSessionHandler">
+                <argument type="service" id="Redis"/>
+                <argument type="collection">
+                    <argument key="ttl" type="closure" id="my.ttl.handler"/>
+                </argument>
+            </service>
+            <!-- some class with an __invoke() method -->
+            <service id="my.ttl.handler" class="Some\InvokableClass">
+                <!-- Inject whatever dependencies you need to be able to resolve a TTL for the current session -->
+                <argument type="service" id="security"/>
+            </service>
+        </services>
+
+    .. code-block:: php
+
+        // config/services.php
+        use Symfony\Component\HttpFoundation\Session\Storage\Handler\RedisSessionHandler;
+
+        $services
+            ->set(RedisSessionHandler::class)
+            ->args([
+                service('Redis'),
+                ['ttl' => closure(service('my.ttl.handler'))],
+            ]);
+
+        $services
+            // some class with an __invoke() method
+            ->set('my.ttl.handler', 'Some\InvokableClass')
+            // Inject whatever dependencies you need to be able to resolve a TTL for the current session
+            ->args([service('security')]);