How to use tracing crate in Rust logging and diagnostics

Use the tracing crate by adding it to your dependencies, initializing a subscriber in main, and using macros like trace! or the #[tracing::instrument] attribute to log events.

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

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

    info!("Application started");
    process_data(42);
}

#[tracing::instrument]
fn process_data(value: i32) {
    tracing::debug!("Processing value: {}", value);
}

Add tracing = "0.1" and tracing-subscriber = "0.3" to your Cargo.toml dependencies.

The tracing crate lets you add diagnostic logs to your Rust code to see what is happening inside your program. It works like a dashboard for your application, showing you events as they occur without slowing down your code. You use it when you need to debug issues or monitor performance in production.