The fluent-logger-ruby library is used to post records from Ruby applications to Fluentd.

This article explains how to use it.


  • Basic knowledge of Ruby

  • Basic knowledge of Fluentd

  • Ruby 2.1 or later

Installing Fluentd

Please refer to the following documents to install fluentd:

Modifying the Config File

Configure Fluentd to use the forward input plugin as its data source:

@type forward
port 24224
<match fluentd.test.**>
@type stdout

Restart agent after configuring.

# for rpm/deb only
$ sudo /etc/init.d/td-agent restart
# or systemd
$ sudo systemctl restart td-agent.service

Using fluent-logger-ruby

Add 'fluent-logger' gem to your Gemfile:

gem 'fluent-logger', "~> 0.7.1"

Initialize and post the records as shown below:

require 'fluent-logger', :host=>'localhost', :port=>24224)"fluentd.test.follow", {"from"=>"userA", "to"=>"userB"})

Executing the script will send the logs to Fluentd:

$ ruby test.rb

The logs should be output to /var/log/td-agent/td-agent.log or the standard output of the Fluentd process via the stdout output plugin.

Production Deployments

Output Plugins

Various output plugins are available for writing records to other destinations:

High-Availability Configurations of Fluentd

For high-traffic websites (more than 5 application nodes), we recommend using the high-availability configuration for td-agent. This will improve the reliability of data transfer and query performance.


Monitoring Fluentd itself is also important. The article below describes the general monitoring methods for td-agent.

If this article is incorrect or outdated, or omits critical information, please let us know. Fluentd is an open-source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.