Cron

Contao periodically executes some tasks via its own cron functionality. The following is a list of tasks executed by Contao’s own bundles:

Task Interval
Generate calendar RSS feeds daily
Purge expired comment subscriptions daily
Purge temp folder daily
Purge search cache daily
Generate XML sitemap daily
Purge expired registrations daily
Purge expired Opt-In tokens daily
Generate news RSS feeds daily
Purge expired newsletter subscriptions daily

Configuring the Cron job

By default the cron tasks are executed after a response is sent back to the visitor when a request to the Contao site has been made.

It is recommended to run PHP via PHP-FPM, otherwise cron execution and search indexing will block any subsequent request by the same user.

You can disable the front end cron by going to System » Settings » Cron job settings and enabling the setting Disable the command scheduler. After disabling the front end cron you should periodically make a request to the _contao/cron route via your own cron job. In a Linux crontab you could use the following for example:

* * * * * wget -q -O /dev/null https://example.org/_contao/cron

Registering Cron Jobs

Registering custom cron jobs is similar to registering to hooks.

Using the PHP array configuration

You can register your own cron jobs using the $GLOBALS['TL_CRON'] arrays. It is an associative array with the following keys, representing the available intervals:

  • minutely
  • hourly
  • daily
  • weekly
  • monthly

To register your own job, add another array item with the class and method of your cron job to one of the intervals in your contao/config/config.php:

// contao/config/config.php
$GLOBALS['TL_CRON']['hourly'][] = [\App\Cron\ExampleCron::class, 'onHourly'];

// src/Cron/ExampleCron.php
namespace App\Cron;

class ExampleCron
{
    public function onHourly(): void
    {
        // Do something …
    }
}

Using service tagging

This feature is only available in Contao 4.9 and later.

Cron jobs can also be registered using the contao.cron service tag with the following options:

Option Type Description
name string Must be contao.cron.
interval string One of the supported intervals: minutely, hourly, daily, weekly or monthly.
method string Optional: the method name in the service. Otherwise the method name will be onInterval automatically.
priority integer Optional: priority of the cron job. By default it will be executed before the legacy cron jobs. Anything with lower than 0 will be executed after legacy callbacks.
cli boolean Optional: If true the cron job will be executed only when the Contao Cron has been invoked via the contao:cron command on the command line. 
# config/services.yaml
services:
    App\Cron\ExampleCron:
        tags:
            -
                name: contao.cron
                interval: daily    # minutely, hourly, daily, weekly, monthly
                method: onDaily    # optional, auto generated from the interval, e.g.: onDaily
                priority: 100      # optional, >0: before $GLOBALS['TL_CRON'], <0: after $GLOBALS['TL_CRON']
                cli: true          # optional, job will only be executed via the contao:cron command

You can also use the Contao\CoreBundle\ServiceAnnotation\Cron service annotation together with the Terminal42\ServiceAnnotationBundle\ServiceAnnotationInterface:

// src/Cron/ExampleCron.php
namespace App\Cron;

use Contao\CoreBundle\ServiceAnnotation\Cron;
use Terminal42\ServiceAnnotationBundle\ServiceAnnotationInterface;

class ExampleCron implements ServiceAnnotationInterface
{
    /**
     * @Cron("minutely", priority=-1)
     */
    public function onMinutely(): void
    {
        // Do something
    }

    /**
     * @Cron("hourly", priority=32, cli=true)
     */
    public function onHourly(): void
    {
        // Do something on CLI only
    }
}