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.

Prerequisites

• Basic knowledge of Java

• Basic knowledge of Fluentd

• Java 6 or higher

Installing Fluentd

Please refer to the following documents to install fluentd.

• ​Install Fluentd with rpm Package​

• ​Install Fluentd with deb Package​

• ​Install Fluentd with Ruby Gem​

• ​Install Fluentd from source​

Modifying the Config File

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

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

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.

<dependencies>
  ...
  <dependency>
    <groupId>org.fluentd</groupId>
    <artifactId>fluent-logger</artifactId>
    <version>${logger.version}</version>
  </dependency>
  ...
</dependencies>

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:

• Examples

  • ​Store Apache Logs into Amazon S3​

  • ​Store Apache Logs into MongoDB​

  • ​Data Collection into HDFS​

• List of Plugin References

  • ​Output to Another Fluentd​

  • ​Output to MongoDB or MongoDB ReplicaSet​

  • ​Output to Hadoop​

  • ​Output to File​

  • ​etc...​

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.

• ​High-Availability Configurations of Fluentd​

Monitoring

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

• ​Monitoring Fluentd​

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.