Mastering Rust - Second Edition

log4rs

The log4rs crate, as the name suggests, is inspired by the popular log4j library from Java. This crate is much more powerful than env_logger and allows for granular logger configuration via YAML files.

We'll build two crates to demonstrate integrating logging via the log4rs crate. One will be a library crate, cargo new my_lib --lib, and the other will be our binary crate, cargo new my_app, which uses my_lib. A cargo workspace directory, called log4rs_demo, contains both of our crates.

Our my_lib crate has the following contents in the lib.rs file:

// log4rs_demo/my_lib/lib.rsuse log::debug;pub struct Config;impl Config {    pub fn load_global_config() {        debug!("Configuration files loaded");    }}

It has a struct called Config with a dummy ...