Fluentd
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Scala
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:

Modifying the Config File

Configure Fluentd to use the forward input plugin as its data source:
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<source>
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@type forward
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port 24224
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</source>
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<match fluentd.test.**>
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@type stdout
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</match>
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Restart agent after configuring.
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# for rpm/deb only
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$ sudo /etc/init.d/td-agent restart
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# or systemd
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$ sudo systemctl restart td-agent.service
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Using fluent-logger-scala

Add the following lines to build.sbt:
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resolvers += "Apache Maven Central Repository" at "http://repo.maven.apache.org/maven2/"
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libraryDependencies += "org.fluentd" %% "fluent-logger-scala" % "(version)"
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See release notes for the revision information.
or
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resolvers += "Sonatype Repository" at "http://oss.sonatype.org/content/repositories/releases"
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libraryDependencies += "org.fluentd" %% "fluent-logger-scala" % "(version)"
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Create an app with the following code:
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import org.fluentd.logger.scala.FluentLoggerFactory
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import scala.collection.mutable.HashMap
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object Sample {
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val LOG = FluentLoggerFactory.getLogger("fluentd.test")
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def main(args: Array[String]): Unit = {
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...
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val data = new HashMap[String, String]();
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data.put("from", "userA");
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data.put("to", "userB");
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LOG.log("follow", data);
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...
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}
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}
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Further information on the API can be found here.
Executing the script will send the logs to Fluentd:
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$ sbt
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> run
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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

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.