fluent/fluent-bit

What is it?

Key features

• 01Collects logs, metrics and traces through a pluggable input system.
• 02Offers more than 70 built-in input, filter and output plugins.
• 03Supports SQL queries for stream processing and transformation.
• 04Provides TLS/SSL and asynchronous I/O for networking.
• 05Allows plugins to be written in C, Lua filters and Go outputs.
• 06Exposes internal metrics over HTTP in Prometheus format.

Use cases

• Forwarding container and host logs from Kubernetes nodes to a central log store.
• Collecting system metrics on Linux or Windows servers and sending them to Prometheus-compatible backends.
• Running on resource-constrained edge or embedded devices that need a small telemetry agent.
• Filtering and enriching log streams before they reach costly storage or analysis systems.

Quick start

1. 1

   Change into the build directory

   cd build
2. 2

   Configure the build with CMake

   cmake ..
3. 3

   Compile Fluent Bit

   make
4. 4

   Run Fluent Bit to send CPU metrics to stdout

   bin/fluent-bit -i cpu -o stdout -f 1

Things to know

• !Building from source requires CMake, Flex, Bison, and the YAML and OpenSSL headers.
• !The README's quick start covers only a source build; packaged installs are linked to external documentation.

In collections

Topics

FAQ

What is fluent-bit?

Lightweight telemetry agent in C that collects, processes and forwards logs, metrics and traces from many sources to many destinations. Fluent Bit is a telemetry agent that gathers logs, metrics and traces from a wide range of inputs, transforms them through filters, and delivers them to external services through output plugins. It is part of the Fluentd ecosystem and is a CNCF project.

Is fluent-bit free to use? What license does it have?

fluent-bit is open source under the Apache-2.0 license. Check the license terms before using it in commercial products.

Is fluent-bit still maintained?

Actively maintained. The last commit to fluent-bit was on Nov 6, 2026.

What can I use fluent-bit for?

Forwarding container and host logs from Kubernetes nodes to a central log store. Collecting system metrics on Linux or Windows servers and sending them to Prometheus-compatible backends. Running on resource-constrained edge or embedded devices that need a small telemetry agent. Filtering and enriching log streams before they reach costly storage or analysis systems.

How do I install fluent-bit?

Change into the build directory: cd build Configure the build with CMake: cmake .. Compile Fluent Bit: make Run Fluent Bit to send CPU metrics to stdout: bin/fluent-bit -i cpu -o stdout -f 1

Where can I get fluent-bit?

The source code and installation instructions are on GitHub: https://github.com/fluent/fluent-bit