> For the complete documentation index, see [llms.txt](https://docs.fluentd.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fluentd.org/monitoring-fluentd/overview.md).

# Overview

This article describes how to monitor Fluentd.

## Fluentd Metrics Monitoring

Fluentd can expose internal metrics via REST API, and works with monitoring tools such as [`Prometheus`](https://prometheus.io/), [`Datadog`](https://www.datadoghq.com/), etc. Our recommendation is to use `Prometheus`, since we will be collaborating more in the future under the [CNCF (Cloud Native Computing Foundation)](https://www.cncf.io/).

* [Monitoring Fluentd (Prometheus)](/monitoring-fluentd/monitoring-prometheus.md)
* [Monitoring Fluentd (Datadog)](https://docs.datadoghq.com/integrations/fluentd/)
* [Monitoring Fluentd (REST API)](/monitoring-fluentd/monitoring-rest-api.md)

## Process Monitoring

Two `ruby` processes (parent and child) are executed. Please make sure that these processes are running.

Here's an example for `td-agent`:

```
/opt/td-agent/embedded/bin/ruby /usr/sbin/td-agent
  --daemon /var/run/td-agent/td-agent.pid
  --log /var/log/td-agent/td-agent.log
```

For `td-agent` on Linux, check the process statuses like this:

```
$ ps w -C ruby -C td-agent --no-heading
32342 ?        Sl     0:00 /opt/td-agent/embedded/bin/ruby /usr/sbin/td-agent --daemon /var/run/td-agent/td-agent.pid --log /var/log/td-agent/td-agent.log
32345 ?        Sl     0:01 /opt/td-agent/embedded/bin/ruby /usr/sbin/td-agent --daemon /var/run/td-agent/td-agent.pid --log /var/log/td-agent/td-agent.log
```

There should be two processes if there is no issue.

## Port Monitoring

Fluentd opens several ports according to the configuration file. We recommend checking the availability of these ports. The default port settings are shown below:

* TCP 0.0.0.0 9880 (HTTP by default)
* TCP 0.0.0.0 24224 (Forward by default)

## Debug Port

A debug port for local communication is recommended for troubleshooting. The following configuration will be required for the debug port:

```
<source>
  @type debug_agent
  bind 127.0.0.1
  port 24230
</source>
```

You can attach the process using the `fluent-debug` command through `dRuby`.

{% hint style="warning" %}
Since v1.19.3 or later, the default value of `bind` parameter was changed from '0.0.0.0' to '127.0.0.1'. If you want to allow access from remote, change it manually to '0.0.0.0'. Be careful to do it at your own risk because this debug feature has no access control and allows executing any valid code.
{% endhint %}

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.