How to Add Logging to a Rust Application

Add the tracing crate to your project and initialize a subscriber in main to capture logs.

1. Add the dependency to Cargo.toml:

[dependencies]
tracing = "0.1"
tracing-subscriber = "0.3"

2. Import the macros and initialize the subscriber in src/main.rs:

use tracing::{info, Level};
use tracing_subscriber;

fn main() {
    tracing_subscriber::fmt()
        .with_max_level(Level::INFO)
        .init();

    info!("Application started");
}

Logging is like adding a notebook to your application that records what happens as it runs. You use it to track errors, monitor performance, or understand user behavior without stopping the program. It helps you see inside the black box of your running code.