# Fluent Bit metrics

{% hint style="info" %}
**Supported event types:** `metrics`
{% endhint %}

Fluent Bit exposes [metrics](/manual/administration/monitoring.md) 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](/manual/data-pipeline/inputs/node-exporter-metrics.md). They can be sent to output plugins including [Prometheus Exporter](/manual/data-pipeline/outputs/prometheus-exporter.md), [Prometheus Remote Write](/manual/data-pipeline/outputs/prometheus-remote-write.md) or [OpenTelemetry](/manual/data-pipeline/outputs/opentelemetry.md).

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

## Configuration parameters

| Key               | Description                                                                                               | Default     |
| ----------------- | --------------------------------------------------------------------------------------------------------- | ----------- |
| `scrape_interval` | The rate at which Fluent Bit internal metrics are collected.                                              | `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](/manual/administration/multithreading.md#inputs). | `false`     |

## Get started

You can run the plugin from the command line or through the configuration file:

### Command line

Run the plugin from the command line using the following command:

```shell
fluent-bit -i fluentbit_metrics -o stdout
```

which returns results like the following:

```
...
[2025/12/02 08:33:54.689265000] [ info] [input:fluentbit_metrics:fluentbit_metrics.0] initializing
[2025/12/02 08:33:54.689272000] [ info] [input:fluentbit_metrics:fluentbit_metrics.0] storage_strategy='memory' (memory only)
[2025/12/02 08:33:54.689917000] [ info] [output:stdout:stdout.0] worker #0 started
[2025/12/02 08:33:54.690115000] [ info] [sp] stream processor started
[2025/12/02 08:33:54.690204000] [ info] [engine] Shutdown Grace Period=5, Shutdown Input Grace Period=2
2025-12-02T07:33:56.692855536Z fluentbit_uptime{hostname="XXXXX.local"} = 2
2025-12-02T07:33:54.687838528Z fluentbit_logger_logs_total{message_type="error"} = 0
2025-12-02T07:33:54.687838528Z fluentbit_logger_logs_total{message_type="warn"} = 0
2025-12-02T07:33:54.690212675Z fluentbit_logger_logs_total{message_type="info"} = 10
2025-12-02T07:33:54.687838528Z fluentbit_logger_logs_total{message_type="debug"} = 0
2025-12-02T07:33:54.687838528Z fluentbit_logger_logs_total{message_type="trace"} = 0
2025-12-02T07:33:54.689222850Z fluentbit_input_bytes_total{name="fluentbit_metrics.0"} = 0
2025-12-02T07:33:54.689222850Z fluentbit_input_records_total{name="fluentbit_metrics.0"} = 0
2025-12-02T07:33:54.689222850Z fluentbit_input_ring_buffer_writes_total{name="fluentbit_metrics.0"} = 0
2025-12-02T07:33:54.689222850Z fluentbit_input_ring_buffer_retries_total{name="fluentbit_metrics.0"} = 0
2025-12-02T07:33:54.689222850Z fluentbit_input_ring_buffer_retry_failures_total{name="fluentbit_metrics.0"} = 0
2025-12-02T07:33:56.692846827Z fluentbit_input_metrics_scrapes_total{name="fluentbit_metrics.0"} = 1
2025-12-02T07:33:54.689563930Z fluentbit_output_proc_records_total{name="stdout.0"} = 0
...
```

### Configuration file

In the following configuration file, the input plugin `fluentbit_metrics` collects metrics every `2` seconds and exposes them through the [Prometheus Exporter](/manual/data-pipeline/outputs/prometheus-exporter.md) 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
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.fluentbit.io/manual/data-pipeline/inputs/fluentbit-metrics.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.