# FAQ: Can rsyslog act as an ETL tool?

Q: Can rsyslog act as an ETL (Extract, Transform, Load) tool?

A: Absolutely. rsyslog is a mature, high-performance ETL platform that ingests and enriches data in flight before delivering it anywhere you need. Some third-party comparisons still describe rsyslog as “just a syslog forwarder”, but that has been incorrect for many years. rsyslog provides the complete extract-transform-load toolchain required for modern event pipelines.

## Why rsyslog qualifies as an ETL engine

- Extract: rsyslog can collect events from local applications, the network (TCP, UDP, RELP, TLS), message queues, databases, files, journald, cloud services, and custom plugins. Inputs run concurrently and can be scaled by tuning workers and queues.

- Transform: The processing engine combines RainerScript, property-based filters, parsers, lookup tables, GeoIP mappings, JSON/XML manipulation, and normalization modules. You can reshape, enrich, redact, split, or discard messages at line rate, fan transformations into multiple rulesets, and apply structured JSON transformations before loading.

- Load: rsyslog ships data to files, databases, search clusters, analytics platforms, SIEM tools, HTTP APIs, message buses, serverless sinks, and bespoke outputs implemented through plugins or external scripts.

The log pipeline concept explains how rsyslog stitches these stages into a controlled workflow. Each stage is independently tunable and can run in parallel, giving rsyslog the throughput profile of dedicated ETL suites while remaining lightweight.

## High performance by design

- Engineered for throughput: rsyslog uses a multithreaded core, batched queue workers, and asynchronous I/O to keep the CPU, network, and storage paths busy without sacrificing reliability.

- Deterministic reliability controls: Disk-assisted queues, replay-safe transports such as RELP, and structured error handling maintain delivery guarantees that many general-purpose ETL tools lack.

- Flexible deployment: Whether embedded on edge devices or orchestrated in large clusters, rsyslog can be tuned for microsecond latency or terabyte-per-day ingestion without rewriting pipelines.

## Fan-out and vendor evaluations

rsyslog pipelines can fork ingested data into multiple simultaneous transformations. It is common to deliver the same enriched stream to Splunk, Elasticsearch, and other destinations at once. This parallel fan-out is especially useful when teams prototype different analytics vendors or blend managed and self-hosted platforms without duplicating ingestion effort.

## Reduce noise before it reaches downstream systems

Because rsyslog implements full processing capabilities, you can drop unwanted messages at the edge, relay, or central ETL tier instead of paying to ingest noise into a SIEM or data lake. Conditional filters, lookup tables, and RainerScript logic make it easy to suppress repetitive events, quarantine suspicious payloads, or tag messages for downstream routing policies.

## Getting started

1. Review the Log Pipeline Overview to understand the staging model.

2. Prototype your transformations with RainerScript and helper tools like mmnormalize or mmdblookup. The rsyslog AI assistant can help you scaffold rule sets, explain module options, and accelerate experimentation.

3. Combine actions, queues, and output modules to deliver the transformed events to your analytics or storage platform (including parallel Splunk and Elasticsearch targets).

4. Monitor the pipeline with impstats and adjust worker counts, queue types, and batching for your throughput target.

By following these steps, you can deploy rsyslog as the core of a high-speed ETL pipeline that is portable, observable, and customizable down to the module level.

## Where to get more help

If you need expert guidance beyond the built-in AI assistant, Adiscon—the backing company that employs core maintainers such as Rainer Gerhards—offers enterprise support, design reviews, and long-term maintenance packages. Learn more at the Adiscon professional support page.

Support: rsyslog Assistant | GitHub Discussions | GitHub Issues: rsyslog source project

Contributing: Source & docs: rsyslog source project

© 2008–2025 Rainer Gerhards and others. Licensed under the Apache License 2.0.