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Sessions

Sessions are handled by the Symfony framework, specifically API and underlying session handlers provided by the HttpFoundation component. It is further enhanced in eZ Platform with support for SiteAccess-aware session cookie configuration.

Note

Use of Memcached, Redis (or experimentally PDO) as session handler is a requirement in a cluster setup, for details see below. For an overview of the clustering feature see Clustering.

Configuration

Symfony offers the possibility to change many session options at application level (i.e. in Symfony framework configuration). These options include:

  • cookie_domain
  • cookie_path
  • cookie_lifetime
  • cookie_secure
  • cookie_httponly

However, in eZ Platform you can set up several sites within one Symfony application, so you can also define session configuration per SiteAccess and SiteAccess group level.

Session options per SiteAccess

All site-related session configuration can be defined per SiteAccess and SiteAccess group (in ezplatform.yml):

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ezpublish:
    system:
        my_siteaccess:
            session:
                # Default session name is eZSESSID{siteaccess_hash}
                # (unique session name per SiteAccess)
                name: my_session_name
                # These are optional. 
                # If not defined they will fall back to Symfony framework configuration, 
                # which itself falls back to default php.ini settings
                cookie_domain: mydomain.com
                cookie_path: /foo
                cookie_lifetime: 86400
                cookie_secure: false
                cookie_httponly: true

Session handlers

In Symfony, a session handler is configured using framework.session.handler_id. Symfony can be configured to use custom handlers, or just fall back to what is configured in PHP by setting it to null (~).

Default configuration

eZ Platform adapts Symfony's defaults to make sure its session save path is always taken into account:

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# Default config.yml session configuration
framework:
    session:
        # handler_id can be set to null (~) like default in Symfony, if it so will use default session handler from php.ini
        # But in order to use %ezplatform.session.save_path%, default eZ Platform instead sets %ezplatform.session.handler_id% to:
        # - session.handler.native_file (default)
        # - ezplatform.core.session.handler.native_redis (recommended value for Cluster usage, using php-redis session handler )
        handler_id: '%ezplatform.session.handler_id%'

Recommendations for production setup

Single-server setup

For a single server, the default file handler is preferred.

Cluster setup

See shared sessions in the clustering guide.

Handling sessions with Memcached

To set up eZ Platform using Memcached you need to:

Alternatively if you need to configure Memcached servers dynamically:

  • Create a Symfony service like this:
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    app.session.handler.native_memcached:
        class: eZ\Bundle\EzPublishCoreBundle\Session\Handler\NativeSessionHandler
        arguments:
         - '%session.save_path%'
         - memcached
  • Set %ezplatform.session.handler_id% (or SESSION_HANDLER_ID env var) to app.session.handler.native_memcached
  • Set %ezplatform.session.save_path% (or SESSION_SAVE_PATH env var) to save_path config for Memcached

Optionally tweak php-memcached session settings for things like session locking.

Handling sessions with Redis

To set up eZ Platform using the Redis you need to:

Alternatively if you have needs to configure Redis servers dynamically:

  • Set %ezplatform.session.handler_id% (or SESSION_HANDLER_ID env var) to ezplatform.core.session.handler.native_redis
  • Set %ezplatform.session.save_path% (or SESSION_SAVE_PATH env var) to save_path config for Redis

eZ Platform Cloud

For eZ Platform Cloud (and Platform.sh), this is already configured in app/config/env/platformsh.php based on .platform.yml config.

If you are on php-redis v4.2.0 and higher, you can optionally tweak php-redis settings for session locking.

Additional notes on using Redis for Sessions

Ideally keep persistence cache and session data separated:

  • Sessions can't risk getting randomly evicted when you run out of memory for cache.
  • You can't completely disable eviction either, as Redis will then start to refuse new entries once full, including new sessions.
  • Either way, you should monitor your Redis instances and make sure you have enough memory set aside for active sessions/cache items.

If you want to make sure sessions survive Redis or server restarts, consider using a persistent Redis instance for sessions.

Alternative storing sessions in database using PDO

For setups where database is preferred for storing sessions, you may use Symfony's PdoSessionHandler, although it is not currently recommended from performance perspective.

Below is a configuration example for eZ Platform. Refer to the Symfony Cookbook for full documentation.

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framework:
    session:
        # ...
        handler_id: session.handler.pdo

parameters:
    pdo.db_options:
        db_table: session
        db_id_col: session_id
        db_data_col: session_value
        db_time_col: session_time

services:
    pdo:
        class: PDO
        arguments:
            dsn: 'mysql:dbname=<mysql_database>'
            user: <mysql_user>
            password: <mysql_password>

    session.handler.pdo:
        class: Symfony\Component\HttpFoundation\Session\Storage\Handler\PdoSessionHandler
        arguments: ['@pdo', '%pdo.db_options%']