Fluent Bit moves log records from where applications produce them to the place a team stores and investigates them. It can read container logs, parse their contents, add useful context and forward them to configured destinations. It is useful as an agent on Kubernetes nodes when logs should survive individual application containers. Collection is only part of the path: buffering, destination failures and saved file positions determine whether records arrive without gaps or duplicates.
Deployment and operating notes
The Fluent project publishes Fluent Bit’s chart in fluent/helm-charts, including an OCI installation route and chart-signature verification guidance. This supersedes the retired stable package. The chart version and Fluent Bit application version are separate: select the chart with Helm’s --version flag and pin the application image with the chart’s image.tag or image.digest setting. A chart upgrade can change the default application image as well as manifests.
Inventory container-runtime log paths, parsers, multiline rules, Kubernetes enrichment, filters, outputs and tail-state storage. Test representative JSON, plain-text and multiline records, including rotated logs and oversized lines, before changing collectors. Preserve state carefully or explicitly accept replay; starting from the beginning can duplicate a large volume of logs. Configure bounded buffering and observe retry or drop behavior when the destination is unavailable. Restrict host mounts and credentials to the required collection path. During rollout, compare records and timestamps at the destination and monitor agent memory and back-pressure. A running DaemonSet does not prove that logs are delivered or retained.
Historical upstream link check · 2026-10-09
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Website availability is separate from project, chart and image support. Use the current guidance and primary sources on this page to assess the distribution.
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Fluent Bit is an open source and multi-platform log forwarder tool which aims to be a generic Swiss knife for log collection and distribution.
We, Treasure Data, as a Big Data company, provide an analytics infrastructure in the Cloud where we provide an end-to-end solution to collect, store and do analytics over the data. Fluent Bit is an integral part of this pipeline where it solves the log collection needs.
Being an open source project, it has been widely adopted to solve logging needs in Cloud Native environments where Docker and Kubernetes are key components; Fluent Bit is a natural fit.
Highlights
Lightweight
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.
Extensible
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.
Features
Event Driven: Fluent Bit as a service is fully event-driven, it only use asynchronous operations to collect and deliver data.
Routing: The data that comes through an Input plugin, is tagged. The Routing mechanism allows specifying where these records should be delivered. It also allows delivering one record to multiple destinations.
Configuration: The service uses a simple and human-readable configuration file, it allows 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 allows performing 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 simplifies the connection process and takes 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.
Sources & further reading
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