Configuration files must be flexible enough for any deployment need, but they must keep a clean and readable format.

Fluent Bit Commands extends a configuration file with specific built-in features. The list of commands available as of Fluent Bit 0.12 series are:

@INCLUDE Command

Configuring a logging pipeline might lead to an extensive configuration file. In order to maintain a human-readable configuration, it's suggested to split the configuration in multiple files.

The @INCLUDE command allows the configuration reader to include an external configuration file, e.g:

[SERVICE]
    Flush 1
​
@INCLUDE inputs.conf
@INCLUDE outputs.conf

The above example defines the main service configuration file and also include two files to continue the configuration:

inputs.conf

[INPUT]
    Name cpu
    Tag  mycpu
​
[INPUT]
    Name tail
    Path /var/log/*.log
    Tag  varlog.*

outputs.conf

[OUTPUT]
    Name   stdout
    Match  mycpu
​
[OUTPUT]
    Name            es
    Match           varlog.*
    Host            127.0.0.1
    Port            9200
    Logstash_Format On

Note that despites the order of inclusion, Fluent Bit will ALWAYS respect the following order:

• Service

• Inputs

• Filters

• Outputs

@SET Command

Fluent Bit supports configuration variables, one way to expose this variables to Fluent Bit is through setting a Shell environment variable, the other is through the @SET command.

The @SET command can only be used at root level of each line, meaning it cannot be used inside a section, e.g:

@SET my_input=cpu
@SET my_output=stdout
​
[SERVICE]
    Flush 1
​
[INPUT]
    Name ${my_input}
​
[OUTPUT]
    Name ${my_output}