Function set_arg_formatter

pub fn set_arg_formatter(
    forrmatter: Box<dyn ArgFormatter + Send + Sync>,
) -> Result<(), ()>

Available on crate feature custom-arg-formatter only.

Use a custom formater to format the args (the actual message) of the record . This function can only be called once and return an Error if called a second time.

This example remove the private user ipv4 loggeg by hickory from the log, if the loglevel is below Debug.

use env_logger::fmt::Formatter;
use log::{Level, Record};
use once_cell::sync::Lazy;
use regex::Regex;
use std::{io, io::Write};

static REGEX: Lazy<Regex> = Lazy::new(|| {
	// https://ihateregex.io/expr/ip/
	Regex::new(r"(\b25[0-5]|\b2[0-4][0-9]|\b[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}")
		.unwrap()
});

fn arg_format(buf: &mut Formatter, record: &Record<'_>) -> io::Result<()> {
	if let Some(mod_path) = record.module_path() {
		if log::max_level() < Level::Debug && mod_path.starts_with("hickory") {
			let message = format!("{}", record.args());
			let message = REGEX.replace_all(&message, "RESTRAINED");
			return writeln!(buf, "{}", message);
		}
	};
	writeln!(buf, "{}", record.args())
}

my_env_logger_style::set_arg_formatter(Box::new(arg_format)).unwrap();