Repository files navigation

A Rust library providing a lightweight loggingfacade.

• log documentation

A logging facade provides a single logging API that abstracts over the actuallogging implementation. Libraries can use the logging API provided by thiscrate, and the consumer of those libraries can choose the loggingimplementation that is most suitable for its use case.

1.61.0+

This version is explicitly tested in CI and may be bumped in any release as needed. Maintaining compatibility with older compilers is a priority though, so the bar for bumping the minimum supported version is set very high. Any changes to the supported minimum version will be called out in the release notes.

Libraries should link only to thelog crate, and use the provided macros tolog whatever information will be useful to downstream consumers:

[dependencies]log ="0.4"

use log::{info, trace, warn};pubfnshave_the_yak(yak:&mutYak){trace!("Commencing yak shaving");loop{matchfind_a_razor(){Ok(razor) =>{info!("Razor located: {razor}");                yak.shave(razor);break;}Err(err) =>{warn!("Unable to locate a razor: {err}, retrying");}}}}

In order to produce log output, executables have to use a logger implementation compatible with the facade.There are many available implementations to choose from, here are some options:

• Simple minimal loggers:
  • env_logger
  • colog
  • simple_logger
  • simplelog
  • pretty_env_logger
  • stderrlog
  • flexi_logger
  • call_logger
  • std-logger
  • structured-logger
  • clang_log
  • ftail
• Complex configurable frameworks:
  • log4rs
  • logforth
  • fern
  • spdlog-rs
• Adaptors for other facilities:
  • syslog
  • systemd-journal-logger
  • slog-stdlog
  • android_log
  • win_dbg_logger
  • db_logger
  • log-to-defmt
  • logcontrol-log
• For WebAssembly binaries:
  • console_log
• For dynamic libraries:
  • You may need to constructan FFI-safe wrapper overlog to initialize in your libraries.
• Utilities:
  • log_err
  • log-reload
  • alterable_logger

Executables should choose a logger implementation and initialize it early in theruntime of the program. Logger implementations will typically include afunction to do this. Any log messages generated before the logger isinitialized will be ignored.

The executable itself may use thelog crate to log as well.

If you enable thekv feature, you can associate structured data with your log records:

use log::{info, trace, warn};pubfnshave_the_yak(yak:&mutYak){// `yak:serde` will capture `yak` using its `serde::Serialize` impl//// You could also use `:?` for `Debug`, or `:%` for `Display`. For a// full list, see the `log` crate documentationtrace!(target ="yak_events", yak:serde;"Commencing yak shaving");loop{matchfind_a_razor(){Ok(razor) =>{info!(razor;"Razor located");                yak.shave(razor);break;}Err(e) =>{// `e:err` will capture `e` using its `std::error::Error` implwarn!(e:err;"Unable to locate a razor, retrying");}}}}