Dynamic flow-control

Starting with version 3.22, syslog-ng OSE uses the log-iw-size() option to allocate a static message window to every flow-controlled log path using the network() and syslog() drivers. In addition, you can configure a dynamic memory buffer that syslog-ng OSE can use to dynamically increase the message window of flow-controlled log paths that have higher traffic. This can be useful in low-memory environments, where only a small subset of the active clients sends messages at high rate.

As a result of these changes the log-fifo-size() option only affects log paths that are not flow-controlled. It is expected that after configuring the dynamic message window, you can decrease the value of log-fifo-size(). For details, see "Managing incoming and outgoing messages with flow-control" in the Administration Guide.

SNMP destination

You can now send SNMP traps directly from syslog-ng OSE using the snmp() destination driver. For details, see "snmp: Sending SNMP traps" in the Administration Guide.

Dynamic template function

A new template function called template can resolve static and dynamic templates in template functions. For example, the name of the template to be invoked can be extracted from the message, or from a name-value pair set using the add-contextual-data() feature. For details, see "Template functions of syslog-ng OSE" in the Administration Guide.

Floating point calculations and numerical template functions

Numerical template functions can now handle floating-point numbers. For details, see the ceil, floor, numerical operations, and round template functions.

Enhancements

• HTTP-based destinations can now accept multiple URLs in various formats.

• The message rate of the loggen command can be changed while loggen is running. Send SIGUSR1 to double the message rate, or SIGUSR2 to halve it, for example: kill -USR1 <loggen-pid>

• The Check Point Log Exporter parser can now parse Check Point log messages in the Splunk format. For details, see "Check Point Log Exporter parser" in the Administration Guide.

• New constants are available in the fetch method of the Python source. For details, see "python-fetcher: writing fetcher-style Python sources" in the Administration Guide.

• Global option can be defined in reusable blocks. For details, see "Reusing configuration blocks" in the Administration Guide.

• The date-parser() now supports microseconds (%f). For details, see "Options of date-parser() parsers" in the Administration Guide.

• The value of add-contextual-data() selectors can be a template or a template function, not only a string. For details, see "Adding metadata from an external file" in the Administration Guide.