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

  • Overview of global settings, configuration options, and examples.

• Parsers Section documentation

  • Detailed guide on defining parsers and supported formats.

• Multiline Parsers Section documentation

  • Explanation of multiline parsing configuration.

• Pipeline Section documentation

  • Details on setting up pipelines and using processors.

• Plugins Section documentation

  • How to load external plugins.

• Upstream Servers Section documentation

  • Guide on setting up and using upstream nodes with supported plugins.

• Environment Variables Section documentation

  • Information on setting environment variables and their scope within Fluent Bit.

• Includes Section documentation

  • Description on how to include external YAML files.