# YAML Configuration

## Before You Get Started

Fluent Bit traditionally offered a `classic` configuration mode, a custom configuration format that we are gradually phasing out. While `classic` mode has served well for many years, it has several limitations. Its basic design only supports grouping sections with key-value pairs and lacks the ability to handle sub-sections or complex data structures like lists.

YAML, now a mainstream configuration format, has become essential in a cloud ecosystem where everything is configured this way. To minimize friction and provide a more intuitive experience for creating data pipelines, we strongly encourage users to transition to YAML. The YAML format enables features, such as processors, that are not possible to configure in `classic` mode.

As of Fluent Bit v3.2, you can configure everything in YAML.

## List of Available Sections

Configuring Fluent Bit with YAML introduces the following root-level sections:

| Section Name        | Description                                                                                                                                                                                                                                     |
| ------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `service`           | Describes the global configuration for the Fluent Bit service. This section is optional; if not set, default values will apply. Only one `service` section can be defined.                                                                      |
| `parsers`           | Lists parsers to be used by components like inputs, processors, filters, or output plugins. You can define multiple `parsers` sections, which can also be loaded from external files included in the main YAML configuration.                   |
| `multiline_parsers` | Lists multiline parsers, functioning similarly to `parsers`. Multiple definitions can exist either in the root or in included files.                                                                                                            |
| `pipeline`          | Defines a pipeline composed of inputs, processors, filters, and output plugins. You can define multiple `pipeline` sections, but they will not operate independently. Instead, all components will be merged into a single pipeline internally. |
| `plugins`           | Specifies the path to external plugins (.so files) to be loaded by Fluent Bit at runtime.                                                                                                                                                       |
| `upstream_servers`  | Refers to a group of node endpoints that can be referenced by output plugins that support this feature.                                                                                                                                         |
| `env`               | Sets a list of environment variables for Fluent Bit. Note that system environment variables are available, while the ones defined in the configuration apply only to Fluent Bit.                                                                |

## Section Documentation

To access detailed configuration guides for each section, use the following links:

* [Service Section documentation](https://docs.fluentbit.io/manual/3.2/administration/configuring-fluent-bit/yaml/service-section)
  * Overview of global settings, configuration options, and examples.
* [Parsers Section documentation](https://docs.fluentbit.io/manual/3.2/administration/configuring-fluent-bit/yaml/parsers-section)
  * Detailed guide on defining parsers and supported formats.
* [Multiline Parsers Section documentation](https://docs.fluentbit.io/manual/3.2/administration/configuring-fluent-bit/yaml/multiline-parsers-section)
  * Explanation of multiline parsing configuration.
* [Pipeline Section documentation](https://docs.fluentbit.io/manual/3.2/administration/configuring-fluent-bit/yaml/pipeline-section)
  * Details on setting up pipelines and using processors.
* [Plugins Section documentation](https://docs.fluentbit.io/manual/3.2/administration/configuring-fluent-bit/yaml/plugins-section)
  * How to load external plugins.
* [Upstream Servers Section documentation](https://docs.fluentbit.io/manual/3.2/administration/configuring-fluent-bit/yaml/upstream-servers-section)
  * Guide on setting up and using upstream nodes with supported plugins.
* [Environment Variables Section documentation](https://docs.fluentbit.io/manual/3.2/administration/configuring-fluent-bit/yaml/environment-variables-section)
  * Information on setting environment variables and their scope within Fluent Bit.
* [Includes Section documentation](https://docs.fluentbit.io/manual/3.2/administration/configuring-fluent-bit/yaml/includes-section)
  * Description on how to include external YAML files.