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Configuration File
This page describes the main configuration file used by Fluent Bit
One of the ways to configure Fluent Bit is using a main configuration file. Fluent Bit allows to use one configuration file which works at a global scope and uses the Format and Schema defined previously.
The main configuration file supports four types of sections:
- Service
- Input
- Filter
- Output
In addition, it's also possible to split the main configuration file in multiple files using the feature to include external files:
- Include File
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 |
Flush | Set the flush time in seconds.nanoseconds. The engine loop uses a Flush timeout to define when is required to flush the records ingested by input plugins through the defined output plugins. | 5 |
Daemon | Boolean value to set if Fluent Bit should run as a Daemon (background) or not. Allowed values are: yes, no, on and off.
note: If you are using a Systemd based unit as the one we provide in our packages, do not turn on this option. | Off |
Log_File | Absolute path for an optional log file. By default all logs are redirected to the standard output interface (stdout). | |
Log_Level | Set the logging verbosity level. Allowed values are: error, warning, info, debug and trace. Values are accumulative, e.g: if 'debug' is set, it will include error, warning, info and debug.
Note that trace mode is only available if Fluent Bit was built with the WITH_TRACE option enabled. | info |
Parsers_File | Path for a parsers configuration file. Multiple Parsers_File entries can be defined within the section. | |
Plugins_File | Path for a plugins configuration file. A plugins configuration file allows to define paths for external plugins, for an example see here. | |
Streams_File | Path for the Stream Processor configuration file. To learn more about Stream Processing configuration go here. | |
HTTP_Server | Enable built-in HTTP Server | Off |
HTTP_Listen | Set listening interface for HTTP Server when it's enabled | 0.0.0.0 |
HTTP_Port | Set TCP Port for the HTTP Server | 2020 |
Coro_Stack_Size | Set the coroutines stack size in bytes. The value must be greater than the page size of the running system. Don't set too small value (say 4096), or coroutine threads can overrun the stack buffer. Do not change the default value of this parameter unless you know what you are doing. | 24576 |
The following is an example of a SERVICE section:
[SERVICE]
Flush 5
Daemon off
Log_Level debug
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 |
Name | Name of the input plugin. |
Tag | Tag name associated to all records comming from this plugin. |
The Name is mandatory and it let 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).
The following is an example of an INPUT section:
[INPUT]
Name cpu
Tag my_cpu
A FILTER section defines a filter (related to an filter plugin), here we will describe the base configuration for each FILTER section. Note that each filter plugin may add it own configuration keys:
Key | Description | |
Name | Name of the filter plugin. | |
Match | A pattern to match against the tags of incoming records. It's case sensitive and support the star (*) character as a wildcard. | |
Match_Regex | A regular expression to match against the tags of incoming records. Use this option if you want to use the full regex syntax. | |
The Name is mandatory and it let 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.
The following is an example of an FILTER section:
[FILTER]
Name stdout
Match *
The OUTPUT section specify a destination that certain records should follow after a Tag match. The configuration support the following keys:
Key | Description | |
Name | Name of the output plugin. | |
Match | A pattern to match against the tags of incoming records. It's case sensitive and support the star (*) character as a wildcard. | |
Match_Regex | A regular expression to match against the tags of incoming records. Use this option if you want to use the full regex syntax. | |
The following is an example of an OUTPUT section:
[OUTPUT]
Name stdout
Match my*cpu
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
[INPUT]
Name cpu
Tag my_cpu
[OUTPUT]
Name stdout
Match my*cpu
To avoid complicated long configuration files is better to split specific parts in different files and call them (include) from one main file.
Starting from Fluent Bit 0.12 the new configuration command @INCLUDE has been added and can be used in the following way:
@INCLUDE somefile.conf
The configuration reader will try to open the path somefile.conf, if not found, it will assume it's a relative path based on the path of the base configuration file, e.g:
- Main configuration file path: /tmp/main.conf
- Included file: somefile.conf
- Fluent Bit will try to open somefile.conf, if it fails it will try /tmp/somefile.conf.
Once the file is found, its contents will replace the
@INCLUDE somefile.conf line. This is a simple textual inclusion. You must still follow the Format and Schema defined previously. For example, you cannot define multiple [SERVICE] sections.The @INCLUDE command only works at top-left level of the configuration line, it cannot be used inside sections.
Wildcard character (*) is supported to include multiple files, e.g:
@INCLUDE input_*.conf
Last modified 3yr ago