Fluent Bit logs

Supported event types: logs

The Fluent Bit logs input plugin routes Fluent Bit internal log output into the pipeline as structured log records. Each record contains a level field and a message field, which lets you ship, filter, or store Fluent Bit internal diagnostic output using the same pipeline you use for all other data.

This plugin is event-driven: records are delivered immediately as the internal logger emits them, not on a polling interval. Fluent Bit enables internal log mirroring automatically when this input is configured.

Internal log records are buffered in a bounded in-memory queue of up to 1024 entries. Records produced before the pipeline is ready, or while the queue is full, aren't delivered through this plugin.

Record format

Each record contains the following fields:

Field	Type	Description
level	String	Severity of the log entry. Possible values: error, warn, info, debug, trace, help.
message	String	The log message text.

Configuration parameters

This plugin has no configuration parameters.

Get started

Command line

fluent-bit -i fluentbit_logs -o stdout

Configuration file

The following example captures Fluent Bit internal logs and writes them to standard output:

fluent-bit.yaml

service:
  flush: 1
  log_level: info

pipeline:
  inputs:
    - name: fluentbit_logs
      tag: internal.logs

  outputs:
    - name: stdout
      match: 'internal.logs'

fluent-bit.conf

[SERVICE]
    Flush     1
    Log_Level info

[INPUT]
    Name  fluentbit_logs
    Tag   internal.logs

[OUTPUT]
    Name  stdout
    Match internal.logs

To forward internal logs to an external destination, replace the output with any supported output plugin. For example, to forward to an OpenTelemetry collector:

fluent-bit.yaml

service:
  flush: 1
  log_level: info

pipeline:
  inputs:
    - name: fluentbit_logs
      tag: internal.logs

  outputs:
    - name: opentelemetry
      match: 'internal.logs'
      host: otel-collector
      port: 4318

fluent-bit.conf

[SERVICE]
    Flush     1
    Log_Level info

[INPUT]
    Name  fluentbit_logs
    Tag   internal.logs

[OUTPUT]
    Name  opentelemetry
    Match internal.logs
    Host  otel-collector
    Port  4318