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use log::{debug, error, info, trace, warn, LevelFilter, SetLoggerError};
use log4rs::{
append::{
console::{ConsoleAppender, Target},
file::FileAppender,
},
config::{Appender, Config, Root},
encode::pattern::PatternEncoder,
filter::threshold::ThresholdFilter,
};
fn main() -> Result<(), SetLoggerError> {
let level = log::LevelFilter::Info;
let file_path = "/tmp/foo.log";
// Build a stderr logger.
let stderr = ConsoleAppender::builder().target(Target::Stderr).build();
// Logging to log file.
let logfile = FileAppender::builder()
// Pattern: https://docs.rs/log4rs/*/log4rs/encode/pattern/index.html
.encoder(Box::new(PatternEncoder::new("{l} - {m}\n")))
.build(file_path)
.unwrap();
// Log Trace level output to file where trace is the default level
// and the programmatically specified level to stderr.
let config = Config::builder()
.appender(Appender::builder().build("logfile", Box::new(logfile)))
.appender(
Appender::builder()
.filter(Box::new(ThresholdFilter::new(level)))
.build("stderr", Box::new(stderr)),
)
.build(
Root::builder()
.appender("logfile")
.appender("stderr")
.build(LevelFilter::Trace),
)
.unwrap();
// Use this to change log levels at runtime.
// This means you can change the default log level to trace
// if you are trying to debug an issue and need more logs on then turn it off
// once you are done.
let _handle = log4rs::init_config(config)?;
error!("Goes to stderr and file");
warn!("Goes to stderr and file");
info!("Goes to stderr and file");
debug!("Goes to file only");
trace!("Goes to file only");
Ok(())
}
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