flexi_logger 0.10.4

An easy-to-configure and flexible logger that writes logs to stderr and/or to files. It allows custom logline formats, and it allows changing the log specification at runtime. It also allows defining additional log streams, e.g. for alert or security messages.
Documentation 
#[cfg(feature = "specfile")]
extern crate flexi_logger;
#[cfg(feature = "specfile")]
#[macro_use]
extern crate log;

#[cfg(feature = "specfile")]
use flexi_logger::{detailed_format, Logger};
#[cfg(feature = "specfile")]
use std::{fs, thread, time};

/// Rudimentary test of the specfile feature, using the file ./tests/logspec.toml.
/// For real test, run this manually, change the duration before to a much higher value (see below),
/// and edit the file while the test is running. You should see the impact immediately -
/// by default, ERR, WARN, and INFO messages are printed. If you change the level in the file,
/// less or more lines should be printed.
#[cfg(feature = "specfile")]
#[cfg_attr(feature = "specfile", test)]
fn test_specfile() {
    let specfile = "./tests/logspec.toml";
    fs::remove_file(specfile).ok();
    Logger::with_str("info")
        .format(detailed_format)
        .start_with_specfile(specfile)
        .unwrap_or_else(|e| panic!("Logger initialization failed because: {}", e));

    let wait = time::Duration::from_millis(1);
    // if you want to give yourself a real chance to update the specfile in between:
    // let wait = time::Duration::from_millis(500);
    for _ in 0..100 {
        thread::sleep(wait);
        error!("This is an error message");
        warn!("This is a warning");
        info!("This is an info message");
        debug!("This is a debug message");
        trace!("This is a trace message");
    }
}