sebastienrousseau/rlg

Near-lock-free structured logging for Rust: records leave the application thread with a few atomic operations and are formatted and written by a background flusher.
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Contents
**Getting started**
- Install — Cargo for the libraries, cargo install for the CLIs and the MCP server
- Requirements — toolchain floor, platforms
- Quick Start — one structured record, fired and flushed
**The rlg ecosystem**
- The rlg ecosystem — rlg, rlg-cli, rlg-report, rlg-mcp, rlg-otlp, rlg-redact, rlg-tower, rlg-test, rlg-wasm, rlg-ebpf
**Library reference**
- Capabilities at a glance — the current surface by theme
- Ecosystem comparison — short matrix; full table at docs/COMPARISON.md
- Benchmarks — headline numbers; full table at docs/BENCHMARKS.md
- Features — module-level capability list
- Configuration — core options
- Examples — runnable example index
**Operational**
- When not to use rlg — limitations
- Development — make targets, fuzzing, CI
- Security — guarantees and compliance
- Documentation — all reference docs
- Stability guarantees — SemVer axis, output stability, minimum toolchain discipline
- License
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Install
As a Rust library
Satellites install the same way, all at the same version:
Command-line tools
From a checkout, make install builds the three binaries and installs
them with their manpages and bash, zsh and fish completions under
/usr/local (PREFIX and DESTDIR are honoured; make uninstall
reverses it). The binaries generate both themselves:
rlg --manpage > rlg.1, rlg --completions zsh > _rlg.
rlg-mcp is also published as a container image,
ghcr.io/sebastienrousseau/rlg-mcp, and listed in the MCP registry.
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Requirements
- **Rust 1.88.0 or newer** (edition 2024). CI builds every library and
binary on 1.88.0; see the toolchain policy.
- **macOS or Linux** for the native sinks (os_log, journald).
Everywhere else, including Windows, rlg writes to a file or stdout.
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Quick Start
fire() checks the level, pushes the record into a ring buffer and
returns; the flusher thread formats it as JSON and writes it to the
platform sink. This block is compiled and run by cargo test.
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The rlg ecosystem
Ten crates at lockstep version 0.0.15, released together.
| Component | Purpose | Use case |
| :--- | :--- | :--- |
| rlg | The engine: 65,536-slot ring buffer, background flusher, 14 formats, native sinks | Structured logging in any Rust program |
| rlg-cli | The rlg binary: filter by level, component or attribute, convert between formats | my-service \| rlg --min-level error --format ecs |
| rlg-report | The rlg-report binary and library: counts by level and component, top messages, latency percentiles | On-call triage, daily error digests |
| rlg-mcp | MCP server: four tools, one prompt, two resources over stdio, streamable HTTP or HTTP+SSE | AI agents reading production logs |
| rlg-otlp | OTLP/HTTP exporter to a local OpenTelemetry Collector | Honeycomb, Datadog, Grafana through a Collector |
| rlg-redact | Scrubs cards, JWTs, bearer tokens, emails, IPv4 addresses and AWS keys in one pass | GDPR and audit-trail safety |
| rlg-tower | tower::Layer emitting one access-log record per request | axum, hyper and other tower services |
| rlg-test | Capture records in a test and assert on them | Libraries testing their own log output |
| rlg-wasm | wasm-bindgen bindings and a WASI 0.2 component interface | Browsers, Deno, Workers, wasmtime hosts |
| rlg-ebpf | Process enrichment, portable; an eBPF enricher scaffold on Linux | Host context on every record |
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Capabilities at a glance
| Area | Capability | Status |
| :--- | :--- | :--- |
| Ingestion | Atomic level filter, ring-buffer push, no lock on the caller's thread | Stable |
| Formats | JSON, NDJSON, ECS, GELF, Logstash, OTLP, MCP, logfmt, CLF, CEF, ELF, W3C, Apache, Log4j XML | Stable |