# Configuration File 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 * Includes * Service * Pipeline * Inputs * Filters * Outputs The YAML configuration file does not support the following sections yet: * Parsers {% hint style="info" %} YAML configuration is used in the smoke tests for containers, so an always-correct up-to-date example is here: . {% endhint %} ## Env The *env* section allows the definition of configuration variables that will be used later in the configuration file. Example: ```yaml # setting up a local environment variable env: flush_interval: 1 # service configuration service: flush: ${flush_interval} log_level: info http_server: on ``` ## Includes The *includes* section allows the files to be merged into the YAML configuration to be identified as a list of filenames. If no path is provided, then the file is assumed to be in a folder relative to the file referencing it. Example: ```yaml # defining file(s) to include into the current configuration. This includes illustrating using a relative path reference includes: - inclusion-1.yaml - subdir/inclusion-2.yaml ``` ## Service The *service* section defines the global properties of the service. The Service 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 | | grace | Set the grace time in `seconds` as an Integer value. The engine loop uses a Grace timeout to define the wait time on exit | 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 like the one we provide in our packages, do not turn on this option. | Off | | dns.mode | Sets the primary transport layer protocol used by the asynchronous DNS resolver, which can be overridden on a per plugin basis | UDP | | log\_file | Absolute path for an optional log file. By default, all logs are redirected to the standard error interface (stderr). | | | log\_level | Set the logging verbosity level. Allowed values are: off, error, warn, 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. Only a single entry is currently supported. | | | plugins\_file | Path for a `plugins` configuration file. A *plugins* configuration file allows the definition of paths for external plugins; for an example, [see here](https://github.com/fluent/fluent-bit/blob/master/conf/plugins.conf). | | | streams\_file | Path for the Stream Processor configuration file. To learn more about Stream Processing configuration go [here](https://docs.fluentbit.io/manual/3.0/stream-processing/introduction). | | | 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 a 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 | | scheduler.cap | Set a maximum retry time in seconds. The property is supported from v1.8.7. | 2000 | | scheduler.base | Sets the base of exponential backoff. The property is supported from v1.8.7. | 5 | | json.convert\_nan\_to\_null | If enabled, NaN is converted to null when fluent-bit converts msgpack to json. | false | | sp.convert\_from\_str\_to\_num | If enabled, Stream processor converts from number string to number type. | true | The following is an example of a *service* section: ```yaml service: flush: 5 daemon: off log_level: debug ``` For scheduler and retry details, please check there: [scheduling and retries](https://docs.fluentbit.io/manual/3.0/scheduling-and-retries#Scheduling-and-Retries) ## Pipeline A *pipeline* section will define a complete pipeline configuration, including *inputs*, *filters* and *outputs* subsections. ```yaml pipeline: inputs: ... filters: ... outputs: ... ``` Each of the subsections for *inputs*, *filters* and *outputs* constitutes an array of maps that has the parameters for each. Most properties are either simple strings or numbers so can be define directly, ie: ```yaml pipeline: inputs: - name: tail tag: syslog path: /var/log/syslog - name: http tag: http_server port: 8080 ``` 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: | Key | Description | | ---------- | -------------------------------------------------------------------------------------------------------------------------------------------------------- | | Name | Name of the input plugin. Defined as subsection of the *inputs* section. | | Tag | Tag name associated to all records coming from this plugin. | | Log\_Level | Set the plugin's logging verbosity level. Allowed values are: off, error, warn, info, debug and trace. Defaults to the *SERVICE* section's *Log\_Level.* | 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. ```yaml 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: | Key | Description | | ------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------- | | Name | Name of the filter plugin. Defined as a subsection of the *filters* section. | | Match | A pattern to match against the tags of incoming records. It's case-sensitive and supports 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. | | Log\_Level | Set the plugin's logging verbosity level. Allowed values are: off, error, warn, info, debug and trace. Defaults to the *SERVICE* section's *Log\_Level.* | 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: ```yaml 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: | Key | Description | | ------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Name | Name of the output plugin. Defined as a subsection of the *outputs* section. | | Match | A pattern to match against the tags of incoming records. It's case-sensitive and supports 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. | | Log\_Level | Set the plugin's logging verbosity level. Allowed values are: off, error, warn, info, debug and trace. The output log level defaults to the *SERVICE* section's *Log\_Level.* | #### Example output The following is an example of an *output* section: ```yaml 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: ```yaml service: flush: 5 daemon: off log_level: debug pipeline: inputs: - name: cpu tag: my_cpu outputs: - name: stdout match: 'my*cpu' ``` ## Processors In recent versions of Fluent-Bit, the input and output plugins can run in separate threads. In Fluent-Bit 2.1.2, we have implemented a new interface called "processor" to extend the processing capabilities in input and output plugins directly without routing the data. This interface allows users to apply data transformations and filtering to incoming data records before they are processed further in the pipeline. This functionality is only exposed in YAML configuration and not in classic configuration mode due to the restriction of nested levels of configuration. [Processor example](#example-using-processors) ### Example: Using processors. The following configuration file example demonstrates the use of processors to change the log record in the input plugin section by adding a new key "hostname" with the value "monox", and we use lua to append the tag to the log record. Also in the ouput plugin section we added a new key named "output" with the value "new data". All these without the need of routing the logs further in the pipeline. ```yaml service: log_level: info http_server: on http_listen: 0.0.0.0 http_port: 2021 pipeline: inputs: - name: random tag: test-tag interval_sec: 1 processors: logs: - name: modify add: hostname monox - name: lua call: append_tag code: | function append_tag(tag, timestamp, record) new_record = record new_record["tag"] = tag return 1, timestamp, new_record end outputs: - name: stdout match: '*' processors: logs: - name: lua call: add_field code: | function add_field(tag, timestamp, record) new_record = record new_record["output"] = "new data" return 1, timestamp, new_record end ```