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 PE 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 PE will revert to using systemd-journal() instead.

 Caution:

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

Declaration:
systemd-journal(options);
Example: 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: 7.0

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

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

log {
	source(s_journald);
	destination(d_network);
};
Example: Filtering for a specific field using the systemd-journal() driver
@version: 7.0

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: Sending all fields in value-pairs using the systemd-journal() driver
@version: 7.0

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 PE application makes this information available in the following macros:

Table 19: Predefined macros
Journald field syslog-ng predefined macro
MESSAGE $MESSAGE
_HOSTNAME $HOST
_PID $PID
_COMM or SYSLOG_IDENTIFIER $PROGRAM If both _COMM and SYSLOG_IDENTIFIER exists, syslog-ng PE uses SYSLOG_IDENTIFIER
SYSLOG_FACILITY $FACILITY_NUM
PRIORITY $LEVEL_NUM
systemd-journal() source options

The systemd-journal() driver has the following options:

default-facility()
Type: facility string
Default: local0

Description: The default facility value if the SYSLOG_FACILITY entry does not exist.

default-level()
Type: string
Default: notice

Description: The default level value if the PRIORITY entry does not exist.

host-override()
Type: string
Default:

Description: Replaces the ${HOST} part of the message with the parameter string.

keep-hostname()
Type: yes or no
Default: no

Description: Enable or disable hostname rewriting.

  • If enabled (keep-hostname(yes)), syslog-ng PE will retain the hostname information read from the systemd journal messages.

  • If disabled (keep-hostname(no)), syslog-ng PE will use the hostname that has been set up for the operating system instance that syslog-ng is running on. To query or set this value, use the hostnamectl command.

This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.

log-fetch-limit()
Type: number
Default: 10

Description: The maximum number of messages fetched from a source during a single poll loop. The destination queues might fill up before flow-control could stop reading if log-fetch-limit() is too high.

max-field-size()
Type: number (characters)
Default: 65536

Description: The maximum length of a field's value.

prefix()
Type: string
Default: .journald.

Description: If this option is set, every non-built-in mapped names get a prefix (for example: ".SDATA.journald."). By default, syslog-ng PE adds the .journald. prefix to every value.

read-old-records()
Type: yes|no
Default: yes

Description: If set to yes, syslog-ng PE will start reading the records from the beginning of the journal, if the journal has not been read yet. If set to no, syslog-ng PE will read only the new records. If the source has a state in the persist file, this option will have no effect.

time-zone()
Type: name of the timezone, or the timezone offset
Default:

Description: The default timezone for messages read from the source. Applies only if no timezone is specified within the message itself.

The timezone can be specified as using the name of the (for example, time-zone("Europe/Budapest")), or as the timezone offset in +/-HH:MM format (for example, +01:00). On Linux and UNIX platforms, the valid timezone names are listed under the /usr/share/zoneinfo directory.

use-fqdn()
Type: yes or no
Default: no

Description: Use this option to add a Fully Qualified Domain Name (FQDN) instead of a short hostname. You can specify this option either globally or per-source. The local setting of the source overrides the global option if available.

TIP: Set use-fqdn() to yes if you want to use the custom-domain() global option.

NOTE: This option has no effect if the keep-hostname() option is enabled (keep-hostname(yes)) and the message contains a hostname.