v4.0.9

Next generation Telemetry Agent for Logs, Metrics and Traces.

August 21, 2025

KNOWLEDGE BASE

Release Notes v4.0.9

Fluent Bit is a Fast and Lightweight Data Processor and Forwarder for Linux, BSD, Windows and macOS. We are proud to announce the availability of Fluent Bit v4.0.9.

Below is a detailed list of changes included in this release…

What’s new ?


Core


  • pipe: Specify linger option for flb_pipes which is build on top of socketpairs on Windows (PR #10836)
  • engine: fix busy chunks on reload. Remove never called code, simpify logic on shutdown (PR #10836)
  • opentelemetry
    • logs: fix handling of missing timestamps (PR #10836)
    • utils: fix checks for numeric attributes (PR #10836)
  • http_client
    • add response and read_idle timeouts (PR #10836)
    • disable connection recycle on timeout exception (PR #10836)
    • fix incomplete error handling in flb_http_do() (PR #10836)
  • downstream: add flb_downstream_pause and flb_downstream_resume api (PR #10836)
  • network: fix strerror_r detection for musl (PR #10836)

Plugins


Contributors

On every release, there are many people involved doing contributions to different areas like bug reporting, troubleshooting, documentation and coding, without these contributions from the community, the project won’t be the same and won’t be in the good shape that it is now. So THANK YOU! to everyone who takes part of this journey!

Join us

We want to hear about you, our community is growing, and you can be part of it!, you can contact us at:

Latest Version

New release on September 04, 2025

Fluent Bit v4.0.9 is out!

Check out the Release Notes, read the Updated Documentation or jump directly to the Downloads Section.

We are part of a wide community, no vendor lock-in.