19.5. Configuring log rotation

The syslog-ng OSE application does not rotate logs by itself. To use syslog-ng OSE for log rotation, consider the following approaches:

Use logrotate together with syslog-ng OSE

  • Ideal for workstations or when processing fewer logs.

  • It is included in most distributions by default.

  • Less scripting is required, only logrotate has to be configured correctly.

  • Requires frequent restart (syslog-ng OSE must be reloaded/restarted when the files are rotated). After rotating the log files, reload syslog-ng OSE using the syslog-ng-ctl reload command, or use another method to send a SIGHUP to syslog-ng OSE.

  • The statistics collected by syslog-ng OSE, and the correlation information gathered with Pattern Database is lost with each restart.

Separate incoming logs based on time, host or other information: 

  • Ideal for central log servers, where regular restart of syslog-ng OSE is unfavorable.

  • Requires shell scripts or cron jobs to remove old logs.

  • It can be done by using macros in the destination name (in the filename, directory name, or the database table name). (For details on using macros, see Section 11.1.2, Templates and macros.)

Example 19.1. File destination for log rotation

This sample file destination configuration stores incoming logs in files that are named based on the current year, month and day, and places these files in directories that are named based on the hostname:

destination d_sorted { file("/var/log/remote/${HOST}/${YEAR}_${MONTH}_${DAY}.log" create-dirs(yes)); };
Example 19.2. Command for cron for log rotation

This sample command for cron removes files older than two weeks from the /var/log/remote directory:

find /var/log/remote/ -daystart -mtime +14 -type f -exec rm {} \;