fluentd
Fluentd is a mature, open-source log collector that aggregates events from multiple sources and routes them to storage, databases, and cloud services. It is a CNCF project with 13+ years of active development and is widely used in production logging infrastructure.
Key facts
Objective fields from the source. Values we can't verify are shown as “Unknown” rather than guessed.
| Field | Value |
|---|---|
| Repository | fluent/fluentd |
| Owner | fluent |
| Primary language | Ruby |
| License | Apache-2.0 — OSI-approved |
| Stars | 13.6k |
| Forks | 1.4k |
| Open issues | 138 |
| Latest release | v1.19.3 (2026-06-25) |
| Last updated | 2026-07-08 |
| Source | https://github.com/fluent/fluentd |
What fluentd is
Written in Ruby, Fluentd provides a plugin-based architecture for ingesting, filtering, and forwarding structured logs and metrics. It supports multiple input/output formats and operates as a standalone daemon or embedded library, handling log aggregation at scale with configurable buffering and routing.
Get the fluentd source
Clone the repository and explore it locally.
git clone https://github.com/fluent/fluentd.gitcd fluentd# follow the project's README for install & configurationNeed it deployed, integrated, or customized instead? DEV.co ships production installs.
Best use cases
Implementation considerations
- Requires Ruby 3.2 or later; ensure runtime is available in target environment.
- Plugin ecosystem is extensive; validate that your target backends (Elasticsearch, S3, etc.) have well-maintained, production-ready plugins.
- Configuration is declarative but non-trivial; plan for config management and version control of fluent.conf files.
- Memory and CPU usage scales with event volume and filter complexity; monitor and tune buffer settings, worker threads, and garbage collection.
- Understand the difference between master (v1) and deprecated v0.12 branches; always use v1+ for new deployments.
When to avoid it — and what to weigh
- Need native binary performance for ultra-high-throughput streaming — Fluentd is Ruby-based; for extreme event volumes (millions/sec) where latency is critical, compiled alternatives (Fluent Bit, Logstash) may be preferred.
- Require out-of-the-box, minimal configuration logging — Fluentd requires explicit configuration for routing and plugins; if you need zero-touch log shipping, managed SaaS or agents with sensible defaults may be better.
- Operating in severely resource-constrained environments — Ruby runtime overhead and gem dependencies may be problematic on edge devices or embedded systems where a lightweight C-based agent is essential.
- Need proprietary vendor lock-in support model — Fluentd is open-source with community support; if your organization requires SLA-backed vendor support contracts, evaluate commercial alternatives.
License & commercial use
Licensed under Apache License 2.0 (Apache-2.0), a permissive OSI-approved license.
Apache 2.0 permits commercial use, modification, and distribution with attribution. You may use Fluentd in proprietary systems and applications. No commercial license is required from the project. However, verify any third-party plugins or dependencies for their own license restrictions.
DEV.co evaluation signals
Editorial assessment — not user reviews. Directional, with an explicit confidence level.
| Signal | Assessment |
|---|---|
| Maintenance | Active |
| Documentation | Strong |
| License clarity | Clear |
| Deployment complexity | Moderate |
| DEV.co fit | Strong |
| Assessment confidence | High |
Third-party security audit by Cure53 is documented (SECURITY_AUDIT.pdf in docs/). OpenSSF Scorecard badge indicates code quality review. CII Best Practices badge reflects security awareness. Verify audit date and findings. Ensure Ruby and plugin dependencies are kept current for vulnerability patches. Secure credential handling for authentication to remote destinations (API keys, passwords) is application responsibility. Network exposure (listening ports, forwarded credentials) should be restricted per deployment model.
Alternatives to consider
Fluent Bit
Lightweight C-based alternative; lower resource footprint, faster for high-volume edge/embedded deployments, but smaller plugin ecosystem.
Logstash (Elastic Stack)
Java-based, tightly integrated with Elasticsearch; richer filtering/transformation DSL, but heavier resource usage and vendor-led development.
Promtail (Grafana Loki)
Purpose-built for Loki log aggregation; simpler configuration for label-based indexing, but narrower use case than Fluentd's general-purpose architecture.
Build on fluentd with DEV.co software developers
Fluentd is production-ready and widely used in Kubernetes and cloud environments. Review the security audit, test plugin compatibility with your backends, and plan configuration management before deployment. Contact us to discuss integration architecture and operational readiness.
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fluentd FAQ
Can I use Fluentd for real-time metrics and logs?
What is the difference between Fluentd and Fluent Bit?
Is Fluentd suitable for my Kubernetes cluster?
How do I secure Fluentd in production?
Software development & web development with DEV.co
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Evaluate Fluentd for Your Logging Infrastructure
Fluentd is production-ready and widely used in Kubernetes and cloud environments. Review the security audit, test plugin compatibility with your backends, and plan configuration management before deployment. Contact us to discuss integration architecture and operational readiness.