CRON_CLASSES - list of cron classes
DJANGO_CRON_LOCK_BACKEND - path to lock class, default: django_cron.backends.lock.cache.CacheLock
DJANGO_CRON_LOCKFILE_PATH - path where to store files for FileLock, default: /tmp
DJANGO_CRON_LOCK_TIME - timeout value for CacheLock backend, default: 24 * 60 * 60 # 24 hours
DJANGO_CRON_CACHE - cache name used in CacheLock backend, default: default
DJANGO_CRON_DELETE_LOGS_OLDER_THAN - integer, number of days after which log entries will be clear (optional - if not set no entries will be deleted)
For more details, see :doc:`Sample Cron Configurations <sample_cron_configurations>` and :doc:`Locking backend <locking_backend>`