The Systemd input plugin allows to collect log messages from the Journald daemon on Linux environments.

Configuration Parameters

The plugin supports the following configuration parameters:

Key

Description

Default

Path

Optional path to the Systemd journal directory, if not set, the plugin will use default paths to read local-only logs.

Max_Fields

Set a maximum number of fields (keys) allowed per record.

8000

Max_Entries

When Fluent Bit starts, the Journal might have a high number of logs in the queue. In order to avoid delays and reduce memory usage, this option allows to specify the maximum number of log entries that can be processed per round. Once the limit is reached, Fluent Bit will continue processing the remaining log entries once Journald performs the notification.

5000

Systemd_Filter

allows to perform a query over logs that contains a specific Journald key/value pairs, e.g: _SYSTEMD_UNIT=UNIT. The Systemd_Filter option can be specified multiple times in the input section to apply multiple filters as required.

Tag

The tag is used to route messages but on Systemd plugin there is an extra functionality: if the tag includes a star/wildcard, it will be expanded with the Systemd Unit file (e.g: host.* => host.UNIT_NAME).

DB

Specify the absolute path of a database file to keep track of Journald cursor.

Read_From_Tail

Start reading new entries. skip entries already stored in Journald.

false

Getting Started

In order to receive Systemd messages, you can run the plugin from the command line or through the configuration file:

Command Line

From the command line you can let Fluent Bit listen for Systemd messages with the following options:

$ fluent-bit -i systemd \
-p systemd_filter=_SYSTEMD_UNIT=docker.service \
-p tag='host.*' -o stdout

In the example above we are collecting all messages coming from the Docker service.

Configuration File

In your main configuration file append the following Input & Output sections:

[SERVICE]
Flush 1
Log_Level info
Parsers_File parsers.conf
[INPUT]
Name systemd
Tag host.*
Systemd_Filter _SYSTEMD_UNIT=docker.service
[OUTPUT]
Name stdout
Match *