Fluent Community Announces Fluent Bit v4.2 Release Alongside 10-Year Anniversary Milestone

New release introduces a Flexible Telemetry Router, Optimized Trace Sampler, and major performance gains across JSON parsing and observability outputs

New York – November 10, 2025 – The Fluent community today announced the release of Fluent Bit v4.2, the latest version of the industry’s leading open-source telemetry processor. Coinciding with its 10th anniversary, Fluent Bit continues to set the standard for lightweight, high-performance, and vendor-neutral observability, trusted by enterprises worldwide.

Fluent Bit has grown from a simple log collector to a comprehensive, multi-signal telemetry agent, with adoption spanning tens of billions of downloads and integration across major Kubernetes distributions from AWS, Google Cloud, Microsoft Azure, and Oracle. Nearly a quarter of Fortune 100 companies have adopted or contributed to Fluent Bit, underscoring its position as a cornerstone of the cloud native ecosystem.

• Flexible Telemetry Routing: The new Telemetry Router enables content-aware routing based on record metadata, attributes, or tags, allowing users to define dynamic data flows without relying on traditional tag-based matching. The new complementary routing metrics provide per-path visibility of record and byte throughput across inputs and outputs.
• Performance Breakthroughs: Pipeline optimizations enable twice the speed of JSON generation through SIMD-accelerated writing, and provide faster and more efficient Trace Sampling with reduced CPU and memory usage.
• Reliability and Security: The new Supervisor Mode continuously monitors and restarts child processes to ensure consistent uptime. The independent Hot Reload Watchdog validates and protects configuration updates at runtime. Lastly, the enhanced TLS session handling with ALPN support strengthens secure connectivity and resilience.
• Expanded Data Outputs and OpenTelemetry Enhancements: The Amazon S3 output now supports Parquet format with Apache Arrow and ZSTD compression, while the OpenTelemetry output introduces updated protocol support and AWS SigV4 authentication.
• Next-Level Observability: The new GPU metrics collector (AMD) and Prometheus textfile collector for .prom files expand system-level introspection and monitoring flexibility.
• Broader Platform Support: Now supporting Debian Trixie, Rocky/AlmaLinux 10, CentOS Stream 10, the latest openSUSE release, and improved Windows Certstore compatibility.

“With Fluent Bit v4.2, we’re raising the bar for performance, reliability, and extensibility while staying true to our founding principles of lightweight and vendor-neutral design,” said Eduardo Silva Pereira, Project Creator and Maintainer, Fluent Bit. “As we celebrate a decade of community-driven innovation, this release reflects both how far we’ve come and how prepared we are for the next decade of observability challenges.”

Since its creation in 2015, Fluent Bit has grown into the most widely used telemetry agent in the cloud native ecosystem, celebrated for its efficiency, scalability, and open governance under the Cloud Native Computing Foundation (CNCF). This anniversary highlights not only a decade of technical progress, but also a thriving, collaborative global community.

The Fluent community recently proposed restructuring Fluentd and Fluent Bit under a unified Fluent organization at CNCF. This change will:

• Create a shared governance model while preserving project independence.
• Enable future growth of new observability projects under the Fluent umbrella.
• Maintain vendor neutrality with no changes to licenses, names, or day-to-day contributions.

Community feedback and voting will be conducted under CNCF guidance to ensure transparency and inclusivity.

Fluent is a CNCF-graduated, community-driven observability project, encompassing Fluent Bit and Fluentd. Focused on high-performance, vendor-neutral telemetry collection and processing, Fluent provides the foundation for cloud-native observability pipelines worldwide.