Syslog

Syslog input plugins allows to collect Syslog messages through a Unix socket server (UDP or TCP) or over the network using TCP or UDP.

Configuration Parameters

The plugin supports the following configuration parameters:

Key

Description

Default

Mode

Defines transport protocol mode: unix_udp (UDP over Unix socket), unix_tcp (TCP over Unix socket), tcp or udp

unix_udp

Listen

If Mode is set to tcp, specify the network interface to bind.

0.0.0.0

Port

If Mode is set to tcp, specify the TCP port to listen for incoming connections.

5140

Path

If Mode is set to unix_tcp or unix_udp, set the absolute path to the Unix socket file.

Unix_Perm

If Mode is set to unix_tcp or unix_udp, set the permission of the Unix socket file.

0644

Parser

Specify an alternative parser for the message. By default, the plugin uses the parser syslog-rfc3164. If your syslog messages have fractional seconds set this Parser value to syslog-rfc5424 instead.

Buffer_Chunk_Size

By default the buffer to store the incoming Syslog messages, do not allocate the maximum memory allowed, instead it allocate memory when is required. The rounds of allocations are set by Chunk_Size in KB. If not set, Chunk_Size is equal to 32 (32KB). Read considerations below when using udp or unix_udp mode.

Buffer_Max_Size

Specify the maximum buffer size in KB to receive a Syslog message. If not set, the default size will be the value of Chunk_Size.

Considerations

  • When using Syslog input plugin, Fluent Bit requires access to the parsers.conf file, the path to this file can be specified with the option -R or through the Parsers_File key on the [SERVER] section (more details below).

  • When udp or unix_udp is used, the buffer size to receive messages is configurable only through the Buffer_Chunk_Size option which defaults to 32kb.

Getting Started

In order to receive Syslog 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 Forward messages with the following options:

$ fluent-bit -R /path/to/parsers.conf -i syslog -p path=/tmp/in_syslog -o stdout

By default the service will create and listen for Syslog messages on the unix socket /tmp/in_syslog

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 syslog
Path /tmp/in_syslog
Chunk_Size 32
Buffer_Size 64
[OUTPUT]
Name stdout
Match *

Testing

Once Fluent Bit is running, you can send some messages using the logger tool:

$ logger -u /tmp/in_syslog my_ident my_message

In Fluent Bit we should see the following output:

$ bin/fluent-bit -R ../conf/parsers.conf -i syslog -p path=/tmp/in_syslog -o stdout
Fluent-Bit v0.11.0
Copyright (C) Treasure Data
[2017/03/09 02:23:27] [ info] [engine] started
[0] syslog.0: [1489047822, {"pri"=>"13", "host"=>"edsiper:", "ident"=>"my_ident", "pid"=>"", "message"=>"my_message"}]

Recipes

The following content aims to provide configuration examples for different use cases to integrate Fluent Bit and make it listen for Syslog messages from your systems.

Rsyslog to Fluent Bit: Network mode over TCP

Fluent Bit Configuration

Put the following content in your fluent-bit.conf file:

[SERVICE]
Flush 1
Parsers_File parsers.conf
[INPUT]
Name syslog
Parser syslog-rfc3164
Listen 0.0.0.0
Port 5140
Mode tcp
[OUTPUT]
Name stdout
Match *

then start Fluent Bit.

RSyslog Configuration

Add a new file to your rsyslog config rules called 60-fluent-bit.conf inside the directory /etc/rsyslog.d/ and add the following content:

action(type="omfwd" Target="127.0.0.1" Port="5140" Protocol="tcp")

then make sure to restart your rsyslog daemon:

$ sudo service rsyslog restart

Rsyslog to Fluent Bit: Unix socket mode over UDP

Fluent Bit Configuration

Put the following content in your fluent-bit.conf file:

[SERVICE]
Flush 1
Parsers_File parsers.conf
[INPUT]
Name syslog
Parser syslog-rfc3164
Path /tmp/fluent-bit.sock
Mode unix_udp
Unix_Perm 0644
[OUTPUT]
Name stdout
Match *

then start Fluent Bit.

RSyslog Configuration

Add a new file to your rsyslog config rules called 60-fluent-bit.conf inside the directory /etc/rsyslog.d/ and place the following content:

$ModLoad omuxsock
$OMUxSockSocket /tmp/fluent-bit.sock
*.* :omuxsock:

Make sure that the socket file is readable by rsyslog (tweak the Unix_Perm option shown above).