Enable tracing in rust to a stdout or log files

My example how to use tracing, logging and testing in rust. Feel free to play with it and copy code to your projects. Merge requests, comments etc are welcome. Please note that this is just a functional example. Nothing special, just to demonstrate how to use tracing and get more insights. You probably need to add some switches to make it more configurable.

Usage example shown in this code

let _guard = init_tracing(true, Level::TRACE);

cargo run                   
    Finished dev [unoptimized + debuginfo] target(s) in 0.16s
     Running `target\debug\test_tokio.exe`
2023-05-11T06:00:04.094565Z DEBUG main ThreadId(01) something happened inside my_span
2023-05-11T06:00:04.094821Z TRACE main ThreadId(01) main:hello_string: return="hello world 🦀 ❤ ❤\u{fe0f} ☮ 翿"
2023-05-11T06:00:04.094904Z  INFO main ThreadId(01) main: hello world 🦀 ❤ ❤️ ☮ 翿
2023-05-11T06:00:04.094917Z  INFO main ThreadId(01) main: 340282366920938463463374607431768211455

Or when switched to file output:

let _guard = init_tracing(false, Level::TRACE);

cargo run
   Compiling test_tokio v0.1.0 (C:\Users\Maciej Bednarz\projects\rust\test_tokio)
    Finished dev [unoptimized + debuginfo] target(s) in 1.52s
     Running `target\debug\test_tokio.exe`
     
cat logs/service.log.2023-05-11

2023-05-11T06:51:25.627924Z DEBUG main ThreadId(01) something happened inside my_span
2023-05-11T06:51:25.628087Z TRACE main ThreadId(01) main:hello_string: return="hello world 🦀 ❤ ❤\u{fe0f} ☮ 翿"
2023-05-11T06:51:25.628158Z  INFO main ThreadId(01) main: hello world 🦀 ❤ ❤️ ☮ 翿
2023-05-11T06:51:25.628182Z  INFO main ThreadId(01) main: 340282366920938463463374607431768211455

Implemented by this function:

/// Initialize tracing
pub fn init_tracing(
    stdout: bool,
    filter: tracing::Level,
) -> tracing_appender::non_blocking::WorkerGuard {
    // Decide which output should be used
    let (writer, guard) = if stdout {
        let (writer, guard) = tracing_appender::non_blocking(std::io::stdout());
        (writer, guard)
    } else {
        let file_appender = tracing_appender::rolling::daily("logs", "service.log");
        let (writer, guard) = tracing_appender::non_blocking(file_appender);
        (writer, guard)
    };

    // Initialize tracing instance
    tracing_subscriber::fmt()
        .with_writer(writer)
        .with_max_level(filter)
        .with_ansi(stdout)
        .with_target(false)
        .with_file(false)
        .with_thread_ids(true)
        .with_thread_names(true)
        .init();

    guard
}

Usage example:

[dependencies]
tokio = { version = "1", features = ["full"] }
tracing = "0.1"
tracing-subscriber = "0.3"
tracing-appender = "0.2.2"

mod helpers;
use helpers::*;

use std::str::{self};

use tracing::{debug, info, span, Level};

#[tracing::instrument(ret, level=Level::TRACE)]
async fn hello_string<'life>() -> &'life str {
    "hello world 🦀 ❤ ❤️ ☮ \u{7fff}"
}

#[tokio::main]
async fn main() {

    let _guard = init_tracing(false, Level::TRACE);
    let op = hello_string();

    // records an event within "my_span".
    debug!("something happened inside my_span");
    let span = span!(Level::INFO, "main");
    let _guard = span.enter();

    let res = op.await;
    info!("{}", res);
    info!("{}", u128::MAX);
}