KNOWLEDGE BASE

Release Notes v5.1.5

Fluent Bit is a Fast and Lightweight Telemetry Agent for Linux, BSD, macOS and Windows. We are proud to announce the availability of Fluent Bit v5.1.5.

For people upgrading from previous versions, please read the Upgrading Notes section of our documentation:

https://docs.fluentbit.io/manual/5.1/installation/upgrade_notes

Fluent Bit v5.1.5 is a maintenance release that adds Chronicle API integration and gzip compression for Google SecOps, along with HTTP PATCH support. It improves log rotation handling, ingestion resource controls, authentication, and delivery reliability.

The release contains 93 commits since v5.1.4, with improvements across routing, HTTP communication, inputs, filters, outputs, and test coverage.

For users upgrading from earlier releases, v5.1.5 also includes the 5.1 series’ expanded output formats: Kafka Avro and optional Protobuf serialization with Schema Registry integration, Arrow and Parquet output for Amazon S3, and Parquet compression options for Google Cloud Storage.

What’s new ?

Core

• routing: honor conditional input routes in pipelines with a single input and output
• HTTP: improve request validation and HTTP/2 request handling for reliable ingestion and delivery
• authentication: strengthen JWT and signing-key validation
• encoding: improve resource control during log serialization and MessagePack processing, including Lua conversion
• compression: improve Snappy decoding reliability and portability
• tracing: improve chunk tracing responsiveness and trace API resource control
• tests: expand coverage for log rotation, ingestion limits, HTTP communication, authentication, routing, compression, and cloud output delivery

Plugins

Inputs

• Tail
  • improve copytruncate rotation handling with pending reads and stale file metadata to keep log collection progressing reliably
• Forward
  • add signal_object_memory_limit to control decoded metrics and traces resource usage, with a default of 100M
• OpenTelemetry
  • add logs_max_size to limit generated log data per request, including group metadata, with a default of 100M
• NGINX Exporter Metrics
  • improve NGINX Plus response validation and collection shutdown handling
• Collectd
  • improve network packet parsing portability

Processors & Filters

• Kubernetes
  • improve handling of incomplete or malformed pod and kubelet metadata
• Parser
  • improve resource cleanup when Key_Name is configured more than once

Outputs

• Chronicle
  • add api=chronicle to send logs through the Google SecOps Chronicle API
  • add compress=gzip for both the legacy Ingestion API and the Chronicle API
  • preserve sub-second timestamp precision and improve failure reporting and retry handling for batches split across multiple requests
• HTTP
  • add PATCH support through http_method and improve cleanup for invalid method configurations
• Google Cloud Logging
  • report HTTP request cache hits and misses accurately
• Google Cloud Logging, BigQuery, and Chronicle
  • keep authentication assertions out of diagnostic logs
• Loki
  • improve tenant header validation before delivery
• CloudWatch Logs
  • improve resource cleanup under memory pressure

Join us

We want to hear from you. Our community keeps growing, and you can be part of it:

• Github: http://github.com/fluent/fluent-bit
• Slack: CNCF Slack, channel #fluent-bit (https://communityinviter.com/apps/cloud-native/cncf)
• Twitter: @fluentbit