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https://github.com/daboross/fern
Simple, efficient logging for Rust
https://github.com/daboross/fern
logging logging-library rust
Last synced: 3 days ago
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Simple, efficient logging for Rust
- Host: GitHub
- URL: https://github.com/daboross/fern
- Owner: daboross
- License: mit
- Created: 2014-12-16T01:43:47.000Z (about 10 years ago)
- Default Branch: main
- Last Pushed: 2024-12-15T10:12:11.000Z (about 2 months ago)
- Last Synced: 2025-01-28T13:46:40.607Z (10 days ago)
- Topics: logging, logging-library, rust
- Language: Rust
- Homepage:
- Size: 700 KB
- Stars: 855
- Watchers: 9
- Forks: 51
- Open Issues: 43
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
Awesome Lists containing this project
README
fern
====
[![crates.io version badge][cratesio-badge]][fern-crate]
[![Build Status][test-status-badge]][test-status-link]
- [documentation][fern-docs]
- [crates.io page][fern-crate]
- [example program][fern-example]
Simple, efficient logging for [Rust].
Logging configuration is recursively branched: formatting, filters, and output can be applied at each
`fern::Dispatch`, applying to increasingly specific kinds of logging.
```rust
// Configure logger at runtime
fern::Dispatch::new()
// Perform allocation-free log formatting
.format(|out, message, record| {
out.finish(format_args!(
"[{} {} {}] {}",
humantime::format_rfc3339(std::time::SystemTime::now()),
record.level(),
record.target(),
message
))
})
// Add blanket level filter -
.level(log::LevelFilter::Debug)
// - and per-module overrides
.level_for("hyper", log::LevelFilter::Info)
// Output to stdout, files, and other Dispatch configurations
.chain(std::io::stdout())
.chain(fern::log_file("output.log")?)
// Apply globally
.apply()?;
// and log using log crate macros!
log::info!("hello, world!");
```
Examples of all features at the [api docs][fern-docs]. See fern in use with this [example command line program][fern-example].
## Project Direction
I've posted a GitHub Discussion talking about the future of fern: https://github.com/daboross/fern/discussions/147
If you've ever used fern, or you do today, I'd love input!
## fern 0.4.4, 0.5.\*, 0.6.\* security warning - `colored` crate + custom global allocator
One of our downstream dependencies, [atty](https://docs.rs/atty/), through
[colored](https://docs.rs/colored/), has an unsoundness issue:
.
This shows up in one situation: if you're using `colored` 0.1.0 and a custom global allocator.
Upgrade to `fern` 0.7.0 to fix.
### Contributing
There's one thing I need right now, more than anything else: input on what fern does well, and what it should keep
doing well. See [Project Direction](#project-direction).
Besides that, I'm open to PRs! I'll probably review promptly, and I'm always open to being nudged if I don't.
For small PRs, I'll mark anything I need changed in a review, and work with you on that.
For larger PRs, I reserve the right to pull in your commits as they are, then fix things I want to be different myself.
In a workplace, I'd try to never do this - but this is a hobby project for me, and I'd rather be overly particular about
fern's implementation than be reasonable.
This is a change from my previous policy.
See [CONTRIBUTING](./CONTRIBUTING.md) for technical information on contributing.
[Rust]: https://www.rust-lang.org/
[test-status-badge]: https://github.com/daboross/fern/workflows/tests/badge.svg?branch=main&event=push
[test-status-link]: https://github.com/daboross/fern/actions/workflows/rust.yml
[issue-resolution-badge]: http://isitmaintained.com/badge/resolution/daboross/fern.svg
[isitmaintained-link]: http://isitmaintained.com/project/daboross/fern
[cratesio-badge]: https://img.shields.io/crates/v/fern.svg
[fern-docs]: https://docs.rs/fern/
[fern-crate]: https://crates.io/crates/fern
[fern-example]: https://github.com/daboross/fern/tree/main/examples/cmd-program.rs
[log]: https://github.com/rust-lang/log