Fluent Bit: Official Manual
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  • Fluent Bit Documentation
  • About
    • What is Fluent Bit?
    • A Brief History of Fluent Bit
    • Fluentd and Fluent Bit
    • License
    • Sandbox and Lab Resources
  • Concepts
    • Key Concepts
    • Buffering
    • Data Pipeline
      • Input
      • Parser
      • Filter
      • Buffer
      • Router
      • Output
  • Installation
    • Getting Started with Fluent Bit
    • Upgrade Notes
    • Supported Platforms
    • Requirements
    • Sources
      • Download Source Code
      • Build and Install
      • Build with Static Configuration
    • Linux Packages
      • Amazon Linux
      • Alma / Rocky Linux
      • Redhat / CentOS
      • Debian
      • Ubuntu
      • Raspbian / Raspberry Pi
    • Docker
    • Containers on AWS
    • Amazon EC2
    • Kubernetes
    • macOS
    • Windows
    • Yocto / Embedded Linux
    • Buildroot / Embedded Linux
  • Administration
    • Configuring Fluent Bit
      • YAML Configuration
        • Service
        • Parsers
        • Multiline Parsers
        • Pipeline
        • Plugins
        • Upstream Servers
        • Environment Variables
        • Includes
      • Classic mode
        • Format and Schema
        • Configuration File
        • Variables
        • Commands
        • Upstream Servers
        • Record Accessor
      • Unit Sizes
      • Multiline Parsing
    • Transport Security
    • Buffering and Storage
    • Backpressure
    • Scheduling and Retries
    • Networking
    • Memory Management
    • Monitoring
    • Multithreading
    • HTTP Proxy
    • Hot Reload
    • Troubleshooting
    • Performance Tips
    • AWS credentials
  • Local Testing
    • Validating your Data and Structure
    • Running a Logging Pipeline Locally
  • Data Pipeline
    • Pipeline Monitoring
    • Inputs
      • Collectd
      • CPU Log Based Metrics
      • Disk I/O Log Based Metrics
      • Docker Events
      • Docker Log Based Metrics
      • Dummy
      • Elasticsearch
      • Exec
      • Exec Wasi
      • Ebpf
      • Fluent Bit Metrics
      • Forward
      • Head
      • Health
      • HTTP
      • Kafka
      • Kernel Logs
      • Kubernetes Events
      • Memory Metrics
      • MQTT
      • Network I/O Log Based Metrics
      • NGINX Exporter Metrics
      • Node Exporter Metrics
      • OpenTelemetry
      • Podman Metrics
      • Process Exporter Metrics
      • Process Log Based Metrics
      • Prometheus Remote Write
      • Prometheus Scrape Metrics
      • Random
      • Serial Interface
      • Splunk
      • Standard Input
      • StatsD
      • Syslog
      • Systemd
      • Tail
      • TCP
      • Thermal
      • UDP
      • Windows Event Log
      • Windows Event Log (winevtlog)
      • Windows Exporter Metrics
    • Parsers
      • Configuring Parser
      • JSON
      • Regular Expression
      • LTSV
      • Logfmt
      • Decoders
    • Processors
      • Content Modifier
      • Labels
      • Metrics Selector
      • OpenTelemetry Envelope
      • Sampling
      • SQL
      • Filters as processors
      • Conditional processing
    • Filters
      • AWS Metadata
      • CheckList
      • ECS Metadata
      • Expect
      • GeoIP2 Filter
      • Grep
      • Kubernetes
      • Log to Metrics
      • Lua
      • Parser
      • Record Modifier
      • Modify
      • Multiline
      • Nest
      • Nightfall
      • Rewrite Tag
      • Standard Output
      • Sysinfo
      • Throttle
      • Type Converter
      • Tensorflow
      • Wasm
    • Outputs
      • Amazon CloudWatch
      • Amazon Kinesis Data Firehose
      • Amazon Kinesis Data Streams
      • Amazon S3
      • Azure Blob
      • Azure Data Explorer
      • Azure Log Analytics
      • Azure Logs Ingestion API
      • Counter
      • Dash0
      • Datadog
      • Dynatrace
      • Elasticsearch
      • File
      • FlowCounter
      • Forward
      • GELF
      • Google Chronicle
      • Google Cloud BigQuery
      • HTTP
      • InfluxDB
      • Kafka
      • Kafka REST Proxy
      • LogDNA
      • Loki
      • Microsoft Fabric
      • NATS
      • New Relic
      • NULL
      • Observe
      • OpenObserve
      • OpenSearch
      • OpenTelemetry
      • Oracle Log Analytics
      • PostgreSQL
      • Prometheus Exporter
      • Prometheus Remote Write
      • SkyWalking
      • Slack
      • Splunk
      • Stackdriver
      • Standard Output
      • Syslog
      • TCP and TLS
      • Treasure Data
      • Vivo Exporter
      • WebSocket
  • Stream Processing
    • Introduction to Stream Processing
    • Overview
    • Changelog
    • Getting Started
      • Fluent Bit + SQL
      • Check Keys and NULL values
      • Hands On 101
  • Fluent Bit for Developers
    • C Library API
    • Ingest Records Manually
    • Golang Output Plugins
    • WASM Filter Plugins
    • WASM Input Plugins
    • Developer guide for beginners on contributing to Fluent Bit
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  • Sections
  • Entries: key/value
  • Indented configuration mode

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  1. Administration
  2. Configuring Fluent Bit
  3. Classic mode

Format and Schema

Fluent Bit might optionally use a configuration file to define how the service will behave.

The schema is defined by three concepts:

  • Sections

  • Entries: key/value

  • Indented Configuration Mode

An example of a configuration file is as follows:

[SERVICE]
    # This is a commented line
    Daemon    off
    log_level debug

Sections

A section is defined by a name or title inside brackets. Using the previous example, a Service section has been set using [SERVICE] definition. The following rules apply:

  • All section content must be indented (four spaces ideally).

  • Multiple sections can exist on the same file.

  • A section must have comments and entries.

  • Any commented line under a section must be indented too.

  • End-of-line comments aren't supported, only full-line comments.

Entries: key/value

A section can contain entries. An entry is defined by a line of text that contains a Key and a Value. Using the previous example, the [SERVICE] section contains two entries: one is the key Daemon with value off and the other is the key Log_Level with the value debug. The following rules apply:

  • An entry is defined by a key and a value.

  • A key must be indented.

  • A key must contain a value which ends in the breakline.

  • Multiple keys with the same name can exist.

Commented lines are set prefixing the # character. Commented lines aren't processed but they must be indented.

Indented configuration mode

Fluent Bit configuration files are based in a strict indented mode. Each configuration file must follow the same pattern of alignment from left to right when writing text. By default, an indentation level of four spaces from left to right is suggested. Example:

[FIRST_SECTION]
    # This is a commented line
    Key1  some value
    Key2  another value
    # more comments

[SECOND_SECTION]
    KeyN  3.14

This example shows two sections with multiple entries and comments. Empty lines are allowed.

Last updated 29 days ago

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