The 'fluent-logger-java' library is used to post records from Java applications to Fluentd.

This article explains how to use the fluent-logger-java library.


  • Basic knowledge of Java

  • Basic knowledge of Fluentd

  • Java 6 or higher

Installing Fluentd

Please refer to the following documents to install fluentd.

Modifying the Config File

Next, please configure Fluentd to use the forward Input plugin as its data source.

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

Please restart your agent once these lines are in place.

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

Using fluent-logger-java

First, please add the following lines to pom.xml. The logger's revision information can be found in CHANGES.txt.


Next, please insert the following lines into your application. Further information regarding the API can be found here.

import java.util.HashMap;
import java.util.Map;
import org.fluentd.logger.FluentLogger;

public class Main {
    private static FluentLogger LOG = FluentLogger.getLogger("fluentd.test");

    public void doApplicationLogic() {
        // ...
        Map<String, Object> data = new HashMap<String, Object>();
        data.put("from", "userA");
        data.put("to", "userB");
        LOG.log("follow", data);
        // ...

Executing the script will send the logs to Fluentd.

$ java -jar test.jar

The logs should be output to /var/log/td-agent/td-agent.log or stdout 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 a high availability configuration of td-agent. This will improve data transfer reliability and query performance.


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

If this article is incorrect or outdated, or omits critical information, please let us know.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

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