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//! This example shows how to configure fern to output really nicely colored
//! logs
//! - when the log level is error, the whole line is red
//! - when the log level is warn, the whole line is yellow
//! - when the log level is info, the level name is green and the rest of the
//! line is white
//! - when the log level is debug, the whole line is white
//! - when the log level is trace, the whole line is gray ("bright black")
use std::time::SystemTime;
use fern::colors::{Color, ColoredLevelConfig};
use log::{debug, error, info, trace, warn};
fn main() {
set_up_logging();
// let's simulate some logging
info!("starting simulation!");
for i in 0..26 {
trace!("loading: {}%, very verbose debbuging information", 4 * i);
if 5 == i {
debug!("this is taking so long... boooring!");
} else if 10 == i {
debug!("still alive! yay!");
} else if 13 == i {
info!("halfway there!");
} else if 16 == i {
debug!("*scratches nose*");
warn!("nose is itching, continuing anyways");
} else if 20 == i {
debug!("uh oh");
warn!(">nose itching intensifies");
error!("HATCHOOO!");
debug!("encountered minor problem, trying to recover");
info!("gesundheit");
debug!("recovered from minor problem, continuing");
} else if 25 == i {
info!("successfully loaded nothing");
info!("have a good time!");
}
}
}
// ===================== Logging Set Up =====================
fn set_up_logging() {
// configure colors for the whole line
let colors_line = ColoredLevelConfig::new()
.error(Color::Red)
.warn(Color::Yellow)
// we actually don't need to specify the color for debug and info, they are white by default
.info(Color::White)
.debug(Color::White)
// depending on the terminals color scheme, this is the same as the background color
.trace(Color::BrightBlack);
// configure colors for the name of the level.
// since almost all of them are the same as the color for the whole line, we
// just clone `colors_line` and overwrite our changes
let colors_level = colors_line.info(Color::Green);
// here we set up our fern Dispatch
fern::Dispatch::new()
.format(move |out, message, record| {
out.finish(format_args!(
"{color_line}[{date} {level} {target} {color_line}] {message}\x1B[0m",
color_line = format_args!(
"\x1B[{}m",
colors_line.get_color(&record.level()).to_fg_str()
),
date = humantime::format_rfc3339_seconds(SystemTime::now()),
target = record.target(),
level = colors_level.color(record.level()),
message = message,
));
})
// set the default log level. to filter out verbose log messages from dependencies, set
// this to Warn and overwrite the log level for your crate.
.level(log::LevelFilter::Warn)
// change log levels for individual modules. Note: This looks for the record's target
// field which defaults to the module path but can be overwritten with the `target`
// parameter:
// `info!(target="special_target", "This log message is about special_target");`
.level_for("pretty_colored", log::LevelFilter::Trace)
// output to stdout
.chain(std::io::stdout())
.apply()
.unwrap();
debug!("finished setting up logging! yay!");
}
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