The fluent-logger-scala library is used to post records from Scala applications to Fluentd.

This article explains how to use it.

Prerequisites

• Basic knowledge of Scala and sbt

• Basic knowledge of Fluentd

• Scala 2.11.0 or later

• sbt 0.12.0 or later

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

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

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

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-scala

Add the following lines to build.sbt:

resolvers += "Apache Maven Central Repository" at "http://repo.maven.apache.org/maven2/"
​
libraryDependencies += "org.fluentd" %% "fluent-logger-scala" % "(version)"

See release notes for the revision information.

or

resolvers += "Sonatype Repository" at "http://oss.sonatype.org/content/repositories/releases"
​
libraryDependencies += "org.fluentd" %% "fluent-logger-scala" % "(version)"

Create an app with the following code:

import org.fluentd.logger.scala.FluentLoggerFactory
import scala.collection.mutable.HashMap
​
object Sample {
  val LOG = FluentLoggerFactory.getLogger("fluentd.test")
​
  def main(args: Array[String]): Unit = {
​
    ...
    val data = new HashMap[String, String]();
    data.put("from", "userA");
    data.put("to", "userB");
    LOG.log("follow", data);
    ...
  }
}

Further information on the API can be found here.

Executing the script will send the logs to Fluentd:

$ sbt
> run

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:

• 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 high-availability configuration for td-agent. This will improve the reliability of data transfer 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 an open-source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.