The 'fluent-logger-node' library is used to post records from Node.js applications to Fluentd.

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

Prerequisites

• Basic knowledge of Node.js and NPM

• Basic knowledge of Fluentd

• Node.js 6.0 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 systemd
$ sudo systemctl restart td-agent.service
# for init.d
$ sudo /etc/init.d/td-agent restart

Using fluent-logger-node

Obtaining the Most Recent Version

The most recent version of fluent-logger-node can be found here.

A Sample Application

A sample Express app using fluent-logger-node is shown below.

package.json

{
  "name": "node-example",
  "version": "0.0.1",
  "dependencies": {
    "express": "^4.16.0",
    "fluent-logger": "^3.2.0"
  }
}

Now use npm to install your dependencies locally:

$ npm install

index.js

This is the simplest web app.

const express = require('express');
const logger = require('fluent-logger');
const app = express();
​
// The 2nd argument can be omitted. Here is a default value for options.
logger.configure('fluentd.test', {
  host: 'localhost',
  port: 24224,
  timeout: 3.0,
  reconnectInterval: 600000 // 10 minutes
});
​
app.get('/', function(request, response) {
  logger.emit('follow', {from: 'userA', to: 'userB'});
  response.send('Hello World!');
});
const port = process.env.PORT || 3000;
app.listen(port, function() {
  console.log("Listening on " + port);
});

Run the app and go to http://localhost:3000/ in your browser. This will send the logs to Fluentd.

$ node index.js

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.