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Configuration File

This page describes the yaml configuration file used by Fluent Bit

One of the ways to configure Fluent Bit is using a YAML configuration file that works at a global scope.

The yaml configuration file supports the following sections:

Env
Service
Pipeline
- Inputs
- Filters
- Outputs

YAML configuration is used in the smoke tests for containers so an always-correct up-to-date example is here: https://github.com/fluent/fluent-bit/blob/master/packaging/testing/smoke/container/fluent-bit.yaml.

Env

The env section allows to configure variables that will be used later on this configuration file.

Example:

# setting up a local environment variable
env:
    flush_interval: 1

# service configuration
service:
    flush:       ${flush_interval}
    log_level:   info
    http_server: on

Service

The service section defines global properties of the service, the keys available as of this version are described in the following table:

The following is an example of a service section:

service:
    flush: 5
    daemon: off
    log_level: debug

For scheduler and retry details, please check there: scheduling and retries

Pipeline

A pipeline section will define a complete pipeline configuration, including inputs, filters and outputs subsections.

pipeline:
    inputs:
        ...
    filters:
        ...
    outputs:
        ...

Each of the subsections for inputs, filters and outputs constitutes an array of maps that has the parameters for each.

pipeline:
    inputs:
        - name: tail
          tag: syslog
          path: /var/log/syslog
        - name: http
          tag: http_server
          port: 8080

As an example, this pipeline consists of two inputs; a tail plugin and an http server plugin. Each plugin has its own map in the array of inputs consisting of simple properties. To use more advanced properties that consist of multiple values the property itself can be defined using an array, ie: the record and allowlist_key properties for the record_modifier filter:

pipeline:
    inputs:
        - name: tail
          tag: syslog
          path: /var/log/syslog
    filters:
        - name: record_modifier
          match: syslog
          record:
              - powered_by calyptia
        - name: record_modifier
          match: syslog
          allowlist_key:
              - powered_by
              - message

In the cases where each value in a list requires two values they must be separated by a space, such as in the record property for the record_modifier filter.

Input

An input section defines a source (related to an input plugin). Here we will describe the base configuration for each input section. Note that each input plugin may add it own configuration keys:

The Name is mandatory and it lets Fluent Bit know which input plugin should be loaded. The Tag is mandatory for all plugins except for the input forward plugin (as it provides dynamic tags).

Example input

The following is an example of an input section for the cpu plugin.

pipeline:
    inputs:
        - name: cpu
          tag: my_cpu

Filter

A filter section defines a filter (related to a filter plugin). Here we will describe the base configuration for each filter section. Note that each filter plugin may add its own configuration keys:

The Name is mandatory and it lets Fluent Bit know which filter plugin should be loaded. The Match or Match_Regex is mandatory for all plugins. If both are specified, Match_Regex takes precedence.

Example filter

The following is an example of a filter section for the grep plugin:

pipeline:
    filters:
        - name: grep
          match: '*'
          regex: log aa

Output

The outputs section specify a destination that certain records should follow after a Tag match. Currently, Fluent Bit can route up to 256 OUTPUT plugins. The configuration supports the following keys:

Example output

The following is an example of an output section:

pipeline:
    outputs:
        - name: stdout
          match: 'my*cpu'

Example: collecting CPU metrics

The following configuration file example demonstrates how to collect CPU metrics and flush the results every five seconds to the standard output:

service:
    flush: 5
    daemon: off
    log_level: debug

pipeline:
    inputs:
        - name: cpu
          tag: my_cpu
    outputs:
        - name: stdout
          match: 'my*cpu'

Configuration File

This page describes the yaml configuration file used by Fluent Bit

One of the ways to configure Fluent Bit is using a YAML configuration file that works at a global scope.

The yaml configuration file supports the following sections:

Env
Service
Pipeline
- Inputs
- Filters
- Outputs

Env

The env section allows to configure variables that will be used later on this configuration file.

Example:

# setting up a local environment variable
env:
    flush_interval: 1

# service configuration
service:
    flush:       ${flush_interval}
    log_level:   info
    http_server: on

Service

The service section defines global properties of the service, the keys available as of this version are described in the following table:

Key

Description

Default Value

The following is an example of a service section:

service:
    flush: 5
    daemon: off
    log_level: debug

For scheduler and retry details, please check there: scheduling and retries

Pipeline

A pipeline section will define a complete pipeline configuration, including inputs, filters and outputs subsections.

pipeline:
    inputs:
        ...
    filters:
        ...
    outputs:
        ...

Each of the subsections for inputs, filters and outputs constitutes an array of maps that has the parameters for each.

pipeline:
    inputs:
        - name: tail
          tag: syslog
          path: /var/log/syslog
        - name: http
          tag: http_server
          port: 8080

pipeline:
    inputs:
        - name: tail
          tag: syslog
          path: /var/log/syslog
    filters:
        - name: record_modifier
          match: syslog
          record:
              - powered_by calyptia
        - name: record_modifier
          match: syslog
          allowlist_key:
              - powered_by
              - message

In the cases where each value in a list requires two values they must be separated by a space, such as in the record property for the record_modifier filter.

Input

An input section defines a source (related to an input plugin). Here we will describe the base configuration for each input section. Note that each input plugin may add it own configuration keys:

Key

Description

The Name is mandatory and it lets Fluent Bit know which input plugin should be loaded. The Tag is mandatory for all plugins except for the input forward plugin (as it provides dynamic tags).

Example input

The following is an example of an input section for the cpu plugin.

pipeline:
    inputs:
        - name: cpu
          tag: my_cpu

Filter

Key

Description

Example filter

The following is an example of a filter section for the grep plugin:

pipeline:
    filters:
        - name: grep
          match: '*'
          regex: log aa

Output

Key

Description

Example output

The following is an example of an output section:

pipeline:
    outputs:
        - name: stdout
          match: 'my*cpu'

Example: collecting CPU metrics

The following configuration file example demonstrates how to collect CPU metrics and flush the results every five seconds to the standard output:

service:
    flush: 5
    daemon: off
    log_level: debug

pipeline:
    inputs:
        - name: cpu
          tag: my_cpu
    outputs:
        - name: stdout
          match: 'my*cpu'