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:
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It is ideal for workstations or when processing fewer logs.
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It is included in most distributions by default.
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Less scripting is required, only logrotate has to be configured correctly.
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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.
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The statistics collected by syslog-ng OSE, and the correlation information gathered with Pattern Database, are lost with each restart.
Separate incoming logs based on time, host or other information:
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It is ideal for central log servers, where regular restart of syslog-ng OSE is unfavorable.
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Requires shell scripts or cron jobs to remove old logs.
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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 Templates and macros.)
Example: 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: 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 {} \;
These sections describe a method of load balancing logs between multiple syslog-ng Open Source Edition (syslog-ng OSE) destinations. The first subsection describes the round robin load balancing method based on the R_MSEC macro of syslog-ng OSE, while the second subsection describes a configuration generator that you can use as an alternative to using the example configuration described in the first subsection.
For more information about the R_MSEC macro and further macros of syslog-ng OSE, see Macros of syslog-ng OSE.
Topics:
This section describes a round robin load balancing method based on the R_MSEC macro of syslog-ng Open Source Edition (syslog-ng OSE) to load balance your logs between multiple syslog-ng OSE destinations.
TIP: If R_MSEC is not precise enough, you can replace it with R_USEC (which uses microseconds instead of milliseconds).
For more information about the R_MSEC macro and further macros of syslog-ng OSE, see Macros of syslog-ng OSE.
Example: round robin load balancing between multiple destinations
The following example is a round-robin load balancing method, based on syslog-ng OSE's R_MSEC macro.
destination d_lb_network {
channel {
channel {
filter {
"0" == "$(% ${R_MSEC} 2)"
};
destination {
network("myhost1"
disk-buffer(mem-buf-length(10000) disk-buf-size(2000000)));
};
flags(final);
};
channel {
filter {
"1" == "$(% ${R_MSEC} 2)"
};
destination {
network("myhost2"
disk-buffer(mem-buf-length(10000) disk-buf-size(2000000)));
};
flags(final);
};
};
};
The filter {" <return value >" == "$(% ${R_MSEC} 2)"}; code snippets (in bold) serve as the basis of the method. This filter separates incoming log messages' timestamp values based on the R_MSEC macro, using a division with remainder method, and distributes the log messages equally between two destinations based on the return value (in this case, 0 or 1).
If you need a file instead of a network destination, replace the network destination with the file in the example (and use the same analogy for any other syslog-ng OSE destinations).
For an alternative method to use the round robin load balancing method based on the R_MSEC macro, see Configuration generator for the load balancing method based on MSEC hashing.
This section describes a configuration generator for the load balancing method based on MSEC hashing to load balance your logs between multiple syslog-ng Open Source Edition (syslog-ng OSE) destinations.
As an alternative to using the example configuration described in Load balancing with a round robin load balancing method based on the R_MSEC macro of syslog-ng OSE , a configuration generator script is also available in syslog-ng OSE:
destination d_lb {network-load-balancer(targets(myhost1 myhost2 myhost3))};
Where destinations share the same configuration except for the destination address, balancing is based on MSEC hashing.
