Fluent Bit: Official Manual
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1.4
1.4
  • Fluent Bit v1.4 Documentation
  • About
    • What is Fluent Bit ?
    • A Brief History of Fluent Bit
    • Fluentd & Fluent Bit
    • License
  • Concepts
    • Key Concepts
    • Buffering
    • Data Pipeline
      • Input
      • Parser
      • Filter
      • Buffer
      • Router
      • Output
  • Installation
    • Upgrade Notes
    • Supported Platforms
    • Requirements
    • Sources
      • Download Source Code
      • Build and Install
      • Build with Static Configuration
    • Linux Packages
      • Amazon Linux
      • Redhat / CentOS
      • Debian
      • Ubuntu
      • Raspbian / Raspberry Pi
    • Docker
    • Amazon
      • Containers on AWS
      • Amazon EC2
    • Kubernetes
    • Yocto / Embedded Linux
    • Windows
  • Administration
    • Configuring Fluent Bit
      • Format and Schema
      • Configuration File
      • Variables
      • Commands
      • Upstream Servers
      • Unit Sizes
    • Security
    • Buffering & Storage
    • Backpressure
    • Scheduling and Retries
    • Memory Management
    • Monitoring
    • Dump Internals / Signal
  • Data Pipeline
    • Inputs
      • Collectd
      • CPU Metrics
      • Disk I/O Metrics
      • Dummy
      • Exec
      • Forward
      • Head
      • Health
      • Kernel Logs
      • Memory Metrics
      • MQTT
      • Network I/O Metrics
      • Process
      • Random
      • Serial Interface
      • Standard Input
      • Syslog
      • Systemd
      • Tail
      • TCP
      • Thermal
      • Windows Event Log
    • Parsers
      • JSON
      • Regular Expression
      • LTSV
      • Logfmt
      • Decoders
    • Filters
      • AWS Metadata
      • Grep
      • Kubernetes
      • Lua
      • Parser
      • Record Modifier
      • Rewrite Tag
      • Standard Output
      • Throttle
      • Nest
      • Modify
    • Outputs
      • Azure
      • BigQuery
      • Counter
      • Datadog
      • Elasticsearch
      • File
      • FlowCounter
      • Forward
      • GELF
      • HTTP
      • InfluxDB
      • Kafka
      • Kafka REST Proxy
      • NATS
      • NULL
      • PostgreSQL
      • Stackdriver
      • Standard Output
      • Splunk
      • TCP & TLS
      • Treasure Data
  • 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
    • Developer guide for beginners on contributing to Fluent Bit
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  1. Administration
  2. Configuring Fluent Bit

Variables

Fluent Bit supports the usage of environment variables in any value associated to a key when using a configuration file.

The variables are case sensitive and can be used in the following format:

${MY_VARIABLE}

When Fluent Bit starts, the configuration reader will detect any request for ${MY_VARIABLE} and will try to resolve its value.

Example

Create the following configuration file (fluent-bit.conf):

[SERVICE]
    Flush        1
    Daemon       Off
    Log_Level    info

[INPUT]
    Name cpu
    Tag  cpu.local

[OUTPUT]
    Name  ${MY_OUTPUT}
    Match *

Open a terminal and set the environment variable:

$ export MY_OUTPUT=stdout

The above command set the 'stdout' value to the variable MY_OUTPUT.

Run Fluent Bit with the recently created configuration file:

$ bin/fluent-bit -c fluent-bit.conf
Fluent Bit v1.4.0
* Copyright (C) 2019-2020 The Fluent Bit Authors
* Copyright (C) 2015-2018 Treasure Data
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

[2020/03/03 12:25:25] [ info] [engine] started
[0] cpu.local: [1491243925, {"cpu_p"=>1.750000, "user_p"=>1.750000, "system_p"=>0.000000, "cpu0.p_cpu"=>3.000000, "cpu0.p_user"=>2.000000, "cpu0.p_system"=>1.000000, "cpu1.p_cpu"=>0.000000, "cpu1.p_user"=>0.000000, "cpu1.p_system"=>0.000000, "cpu2.p_cpu"=>4.000000, "cpu2.p_user"=>4.000000, "cpu2.p_system"=>0.000000, "cpu3.p_cpu"=>1.000000, "cpu3.p_user"=>1.000000, "cpu3.p_system"=>0.000000}]

As you can see the service worked properly as the configuration was valid.

Last updated 5 years ago

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