# Fluent Bit metrics

Fluent Bit exposes [metrics](https://docs.fluentbit.io/manual/4.1/administration/monitoring) to let you monitor the internals of your pipeline. The collected metrics can be processed similarly to those from the [Prometheus Node Exporter input plugin](https://docs.fluentbit.io/manual/4.1/data-pipeline/inputs/node-exporter-metrics). They can be sent to output plugins including [Prometheus Exporter](https://docs.fluentbit.io/manual/4.1/data-pipeline/outputs/prometheus-exporter), [Prometheus Remote Write](https://docs.fluentbit.io/manual/4.1/data-pipeline/outputs/prometheus-remote-write) or [OpenTelemetry](https://docs.fluentbit.io/manual/4.1/data-pipeline/outputs/opentelemetry).

{% hint style="info" %}
Metrics collected with Node Exporter Metrics flow through a separate pipeline from logs and current filters don't operate on top of metrics.
{% endhint %}

## Configuration

| Key               | Description                                                                                                                         | Default     |
| ----------------- | ----------------------------------------------------------------------------------------------------------------------------------- | ----------- |
| `scrape_interval` | The rate at which metrics are collected from the host operating system.                                                             | `2` seconds |
| `scrape_on_start` | Scrape metrics upon start, use to avoid waiting for `scrape_interval` for the first round of metrics.                               | `false`     |
| `threaded`        | Indicates whether to run this input in its own [thread](https://docs.fluentbit.io/manual/4.1/administration/multithreading#inputs). | `false`     |

## Get started

### Configuration file

In the following configuration file, the input plugin `node_exporter_metrics` collects metrics every `2` seconds and exposes them through the [Prometheus Exporter](https://docs.fluentbit.io/manual/4.1/data-pipeline/outputs/prometheus-exporter) output plugin on HTTP/TCP port `2021`.

{% tabs %}
{% tab title="fluent-bit.yaml" %}

```yaml
service:
  flush: 1
  log_level: info

pipeline:
  inputs:
    - name: fluentbit_metrics
      tag: internal_metrics
      scrape_interval: 2

  outputs:
    - name: prometheus_exporter
      match: internal_metrics
      host: 0.0.0.0
      port: 2021
```

{% endtab %}

{% tab title="fluent-bit.conf" %}

```
# Fluent Bit Metrics + Prometheus Exporter
# -------------------------------------------
# The following example collects Fluent Bit metrics and exposes
# them through a Prometheus HTTP endpoint.
#
# After starting the service try it with:
#
# $ curl http://127.0.0.1:2021/metrics
#
[SERVICE]
  flush           1
  log_level       info

[INPUT]
  name            fluentbit_metrics
  tag             internal_metrics
  scrape_interval 2

[OUTPUT]
  name            prometheus_exporter
  match           internal_metrics
  host            0.0.0.0
  port            2021
```

{% endtab %}
{% endtabs %}

You can test the expose of the metrics by using `curl`:

```shell
curl http://127.0.0.1:2021/metrics
```