6.16. systemd-journal: Collecting messages from the systemd-journal system log storage

The systemd-journal() source is used on various Linux distributions, such as RHEL (from RHEL7) and CentOS. The systemd-journal() source driver can read the structured name-value format of the journald system service, making it easier to reach the custom fields in the message. By default, syslog-ng OSE adds the .journald. prefix to the name of every parsed value.

The systemd-journal() source driver is designed to read only local messages through the systemd-journal API. It is not possible to set the location of the journal files, or the directories.

Note

The log-msg-size() option is not applicable for this source. Use the max-field-size() option instead.

Note

This source will not handle the following cases:

  • corrupted journal file

  • incorrect journal configuration

  • any other journald-related bugs

Note

If you are using RHEL-7, the default source in the configuration is systemd-journal() instead of unix-dgram("/dev/log") and file("/proc/kmsg"). If you are using unix-dgram("/dev/log") or unix-stream("/dev/log") in your configuration as a source, syslog-ng OSE will revert to using systemd-journal() instead.

Warning

Only one systemd-journal() source can be configured in the configuration file. If there are more than one systemd-journal() sources configured, syslog-ng OSE will not start.

Declaration: 

systemd-journal(options);
Example 6.33. Sending all fields through syslog protocol using the systemd-journal() driver

To send all fields through the syslog protocol, enter the prefix in the following format: ".SDATA.<name>".

@version: 3.13

source s_journald {
	systemd-journal(prefix(".SDATA.journald."));
};

destination d_network {
	syslog("server.host");
};

log {
	source(s_journald);
	destination(d_network);
};
Example 6.34. Filtering for a specific field using the systemd-journal() driver
@version: 3.13

source s_journald {
	systemd-journal(prefix(".SDATA.journald."));
};

filter f_uid {"${.SDATA.journald._UID}" eq "1000"};

destination d_network {
	syslog("server.host");
};

log {
	source(s_journald);
	filter(f_uid);
	destination(d_network);
};
Example 6.35. Sending all fields in value-pairs using the systemd-journal() driver
@version: 3.13

source s_local {
	systemd-journal(prefix("journald."));
};

destination d_network {
	network("server.host" template("$(format_json --scope rfc5424 --key journald.*)\n"));
};

log {
	source(s_local);
	destination(d_network);
};

The journal contains credential information about the process that sent the log message. The syslog-ng OSE application makes this information available in the following macros:

Journald fieldsyslog-ng predefined macro
MESSAGE$MESSAGE
_HOSTNAME$HOST
_PID$PID
_COMM or SYSLOG_IDENTIFIER$PROGRAM If both _COMM and SYSLOG_IDENTIFIER exists, syslog-ng OSE uses SYSLOG_IDENTIFIER
SYSLOG_FACILITY$FACILITY_NUM
PRIORITY$LEVEL_NUM