Syslog
The standard Drupal 8 installation enables a module called Database logging.
The Database logging module records log entries that are created by different modules and can be viewed at Reports | Recent log entries (admin/reports/dblog).
However, this means that data is written to the database, so often the database logging module is turned off in production websites for performance reasons.
The Syslog module is an alternative logging module, which logs the same data to the system log of the operating system Drupal is running in.
This is considered to be a faster operation than a database write and therefore is preferable for production sites.
You can alter the settings of the Syslog module by navigating to Configuration | Development | Logging and errors (admin/config/development/logging).
When this module is activated, Drupal's log messages will appear in the main system log on your server. You can specify log labels and patterns to help you filter Drupal messages from other content...
