Use this documentation with care! It describes
the heavily outdated version 5, which was actively
developed around 2010 and is considered dead by the
rsyslog team for many years now.
This documentation reflects the latest update of the previously existing (now removed) v5-stable branch. It describes the 5.10.2 version, which was never released. As such, it contains some content that does not apply to any released version.
To obtain the doc that properly matches your installed v5 version, obtain the doc set from your distro. Each version of rsyslog contained the version that exactly matches it.
As general advise, it is strongly suggested to upgrade to the current version supported by the rsyslog project. The current version can always be found on the right-hand side info box on the rsyslog web site.
Note that there is no rsyslog community support available for this heavily outdated version. If you need to stick with it, please ask your distribution for support.
Failover Syslog Server¶
There are often situations where syslog data from the local system should be sent to a central syslogd (for consolidation, archival and whatever other reasons). A common problem is that messages are lost when the central syslogd goes down. Rsyslog has the capability to work with failover servers to prevent message loss. A perquisite is that TCP based syslog forwarding is used to sent to the central server. The reason is that with UDP there is no reliable way to detect the remote system has gone away. Let’s assume you have a primary and two secondary central servers. Then, you can use the following config file excerpt to send data to them: rsyslog.conf:
*.* @@primary-syslog.example.com $ActionExecOnlyWhenPreviousIsSuspended on & @@secondary-1-syslog.example.com & @@secondary-2-syslog.example.com & /var/log/localbuffer $ActionExecOnlyWhenPreviousIsSuspended off
This selector processes all messages it receives (.). It tries to forward every message to primary-syslog.example.com (via tcp). If it can not reach that server, it tries secondary-1-syslog.example.com, if that fails too, it tries secondary-2-syslog.example.com. If neither of these servers can be connected, the data is stored in /var/log/localbuffer. Please note that the secondaries and the local log buffer are only used if the one before them does not work. So ideally, /var/log/localbuffer will never receive a message. If one of the servers resumes operation, it automatically takes over processing again.