rlg

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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

[dependencies]
rlg = "0.0.18"

Satellites install the same way, all at the same version:

[dependencies]
rlg-otlp   = "0.0.18"  # ship records to an OpenTelemetry Collector
rlg-tower  = "0.0.18"  # per-request access logs for tower services
rlg-redact = "0.0.18"  # scrub secrets and PII before they are written

[dev-dependencies]
rlg-test   = "0.0.18"  # assert on captured records in tests

Command-line tools

cargo install rlg-cli      # `rlg`: filter and convert log files
cargo install rlg-report   # `rlg-report`: summaries by level, component and message
cargo install rlg-mcp      # `rlg-mcp`: log files as tools for AI agents

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 1.89.0 or newer (edition 2024). CI builds every library and binary on 1.89.0; 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

use rlg::log::Log;
use rlg::log_format::LogFormat;

fn main() {
    // Keep the guard for the life of the program: dropping it flushes
    // pending records and stops the background thread.
    let _guard = rlg::init().unwrap();

    Log::info("User authenticated")
        .component("auth-service")
        .with("user_id", 42)
        .format(LogFormat::JSON)
        .fire();
}

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 0.0.18, 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

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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
Sinks	os_log (macOS), journald (Linux), file, stdout	Stable
Sinks	io_uring file sink (Linux, uring feature)	Scaffold
Configuration	TOML load, validation, polling hot-reload (tokio feature)	Stable
Bridges	log facade via rlg::init(); tracing layer (tracing-layer feature)	Stable
Export	OTLP/HTTP to a local Collector (rlg-otlp)	Stable
Agents	MCP server over stdio, streamable HTTP and HTTP+SSE (rlg-mcp)	Stable
Enrichment	eBPF kernel context (rlg-ebpf, Linux)	Scaffold

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