Fluent Bit

Fluent Bit v0.8.5 is out!

It have been released on Sep 05, 2016, check out the Release Notes, read the Updated Documentation or jump directly to the Downloads Section.

Fluent Bit is an open source data collector, which allows you to collect data from different sources, unify it and send it to multiple destinations. It's used to collect system metrics from Embedded Linux environments, as a logging layer library for applications that needs integration with third party services like Elasticsearch or to collect application logs from Docker containers.

Fluent Bit is written in C, have a pluggable architecture supporting around 15 extensions. It's fast and lightweight and provide the required security for network operations through TLS.



It have been designed to be lightweight and provide high performance. All I/O operations are made in asynchronous mode (event-driven), all data internally is serialized in binary mode.


All input and output features are implemented through the plugins interface. At build enable just include what you really need. Create your own plugins easily.

Built-in Metrics

Meassuring is important. Fluent Bit comes with native plugins to gather metrics from your CPU and Memory usage on Linux systems.


Event Driven

Fluent Bit as a service is fully event-driven, it only use asynchronous operations to collect and deliver data.


The data that comes through an Input plugin, is tagged. The Routing mechanism allows to specify where these records should be delivered. It also allows to deliver one record to multiple destinations.


The service use a simple and human-readable configuration file, it allow to specify how it will behave, which features to enable and how Routing is performed. Optionally Fluent Bit can run from the command line without it.

I/O Handler

The Input/Output layer provides an abstraction that allow to perform read/write operations in an asynchronous way.

Upstream Manager

When dealing with upstream backends like remote network services, handling TCP connections can be challenging. The Upstream manager simplify the connection process and take care of timeout/network exceptions and Keepalive states.

TLSv1.2 / Security

When delivering data to destinations, output plugins inherit full TLS capabilities in an abstracted way. Add your certificates as required.