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'
Fluent::Logger::FluentLogger.open(nil, :host=>'localhost', :port=>24224)
Fluent::Logger.post("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If this article is incorrect or outdated, or omits critical information, please let us know.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.
Last modified 2yr ago