slog
slog is a mature, battle-tested Rust logging library focused on structured, contextual, and composable logging. It offers a modular ecosystem with feature crates for different output formats and backends, though the maintainers recommend evaluating tracing as an alternative, especially for async-heavy workloads.
Key facts
Objective fields from the source. Values we can't verify are shown as “Unknown” rather than guessed.
| Field | Value |
|---|---|
| Repository | slog-rs/slog |
| Owner | slog-rs |
| Primary language | Rust |
| License | Apache-2.0 — OSI-approved |
| Stars | 1.7k |
| Forks | 100 |
| Open issues | 56 |
| Latest release | v2.8.2 (2025-10-11) |
| Last updated | 2026-06-01 |
| Source | https://github.com/slog-rs/slog |
What slog is
slog provides a core logging abstraction in Rust with pluggable drains (backends) for flexibility. It supports hierarchical loggers, structured key-value logging, and contextual chaining. The ecosystem includes optional crates for async logging, JSON output, syslog integration, and terminal formatting. Minimum supported Rust version is 1.61+.
Get the slog source
Clone the repository and explore it locally.
git clone https://github.com/slog-rs/slog.gitcd slog# follow the project's README for install & configurationNeed it deployed, integrated, or customized instead? DEV.co ships production installs.
Best use cases
Implementation considerations
- Steep learning curve: understand drain composability, context chains, and initialization patterns before deploying; review examples and wiki documentation thoroughly.
- Modular by nature: core crate is minimal; you will likely need slog-term, slog-async, or custom drains to achieve production-ready logging—plan crate selection upfront.
- Minimum Rust version 1.61+; ensure your MSRV policy aligns with this baseline.
- Performance is reported as very good, but formal benchmarks vs. tracing or std log are not provided; validate latency and throughput for your workload.
- Community support available via Gitter chat; however, documentation gaps are acknowledged in the README; expect to read code and examples to fill gaps.
When to avoid it — and what to weigh
- Heavy async/await and real-time async debugging required — The official README explicitly recommends evaluating tracing for async workloads. slog's async support exists (via slog-async) but tracing has more mature async instrumentation and larger community support for debugging async code.
- You need a single, zero-configuration logging solution — slog is modular and composable by design; this requires understanding drains and chains. If you want immediate, minimal-config logging out of the box, sloggers (a third-party wrapper) or tracing may be faster onboarding.
- Large, active development team and frequent updates expected — slog has one original maintainer (Dawid Ciężarkiewicz) with potential shared ownership. Updates are stable but infrequent. Tracing benefits from Tokio/larger ecosystem backing and more frequent improvements.
- Production debugging at scale with distributed tracing — tracing has better integration with observability platforms and distributed tracing standards. slog is output-only; it does not natively provide span-based tracing or correlation for microservices.
License & commercial use
Licensed under Apache License 2.0 (Apache-2.0), a permissive OSI-approved license.
Apache-2.0 is a permissive license permitting commercial use, modification, and distribution, provided copyright notices and license text are retained. No known restrictions on commercial use. However, the README notes that cargo-crev verification is recommended to assess trustworthiness of this and all dependencies.
DEV.co evaluation signals
Editorial assessment — not user reviews. Directional, with an explicit confidence level.
| Signal | Assessment |
|---|---|
| Maintenance | Moderate |
| Documentation | Adequate |
| License clarity | Clear |
| Deployment complexity | Low |
| DEV.co fit | Good |
| Assessment confidence | High |
No known critical vulnerabilities disclosed in the data. As a logging library, slog does not perform cryptography, network operations, or authentication itself. Security posture depends on drain implementations and user code serializing sensitive data. Follow best practices: avoid logging passwords, API keys, or PII; use structured fields to redact or filter sensitive values. Verify dependencies (especially third-party drains) via cargo-crev as recommended in README.
Alternatives to consider
tracing (Tokio ecosystem)
Explicitly recommended in slog README as the modern go-to for Rust logging/tracing. Better async support, distributed tracing integration, larger community, and more frequent updates. Preferred for async-heavy microservices and observability tooling.
log (Rust standard facade)
Minimal, zero-config facade for logging. Lacks structured logging, contextual chaining, and composability. Suitable only for simple projects or when you want to delegate logging to downstream crates.
env_logger
Built on log facade, provides easy environment-variable-based filtering and terminal output. No structured logging or advanced composition. Good for quick prototypes or CLI tools; insufficient for complex production services.
Build on slog with DEV.co software developers
slog is a proven, stable choice for structured logging in synchronous Rust applications. Review the README, explore the ecosystem crates, and join the Gitter community to discuss fit for your use case. Consider tracing if async/distributed tracing is critical.
Talk to DEV.coRelated on DEV.co
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slog FAQ
Should we adopt slog or tracing?
How do I configure slog without writing boilerplate?
What is the performance impact of slog?
Is slog safe to use in production?
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Evaluate slog for your Rust project
slog is a proven, stable choice for structured logging in synchronous Rust applications. Review the README, explore the ecosystem crates, and join the Gitter community to discuss fit for your use case. Consider tracing if async/distributed tracing is critical.