# Ruby

The [`fluent-logger-ruby`](http://github.com/fluent/fluent-logger-ruby) library is used to post records from Ruby applications to Fluentd.

This article explains how to use it.

## Prerequisites

* Basic knowledge of Ruby
* Basic knowledge of Fluentd
* Ruby 2.1 or later

## Installing Fluentd

Please refer to the following document to install Fluentd:

* [Installation](https://docs.fluentd.org/installation)

## Modifying the Config File

Configure Fluentd to use the [`forward`](https://docs.fluentd.org/input/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-ruby`

Add 'fluent-logger' gem to your `Gemfile`:

```
gem 'fluent-logger', "~> 0.7.1"
```

Initialize and post the records as shown below:

```
require 'fluent-logger'
Fluent::Logger::FluentLogger.open(nil, :host=>'localhost', :port=>24224)
Fluent::Logger.post("fluentd.test.follow", {"from"=>"userA", "to"=>"userB"})
```

Executing the script will send the logs to Fluentd:

```
$ ruby test.rb
```

The logs should be output to `/var/log/td-agent/td-agent.log` or the standard output of the Fluentd process via the [`stdout`](https://docs.fluentd.org/output/stdout) output plugin.

## Production Deployments

### Output Plugins

Various [output plugins](https://docs.fluentd.org/output) are available for writing records to other destinations:

* Examples
  * [Store Apache Logs into Amazon S3](https://docs.fluentd.org/how-to-guides/apache-to-s3)
  * [Store Apache Logs into MongoDB](https://docs.fluentd.org/how-to-guides/apache-to-mongodb)
  * [Data Collection into HDFS](https://docs.fluentd.org/how-to-guides/http-to-hdfs)
* List of Plugin References
  * [Output to Another Fluentd](https://docs.fluentd.org/output/forward)
  * [Output to MongoDB](https://docs.fluentd.org/output/mongo) or [MongoDB ReplicaSet](https://docs.fluentd.org/output/mongo_replset)
  * [Output to Hadoop](https://docs.fluentd.org/output/webhdfs)
  * [Output to File](https://docs.fluentd.org/output/file)
  * [etc...](http://fluentd.org/plugin/)

### 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.

* [High-Availability Configurations of Fluentd](https://docs.fluentd.org/deployment/high-availability)

### Monitoring

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

* [Monitoring Fluentd](https://docs.fluentd.org/monitoring-fluentd/overview)

If this article is incorrect or outdated, or omits critical information, please [let us know](https://github.com/fluent/fluentd-docs-gitbook/issues?state=open). [Fluentd](http://www.fluentd.org/) is an open-source project under [Cloud Native Computing Foundation (CNCF)](https://cncf.io/). All components are available under the Apache 2 License.