How to set custom timestamp format using tracing-subscriber?

Question

I am trying to use tracing-subscriber crate for logging purposes. So far, I was able to use the file rolling correctly and log the events in a file.

let appender = tracing_appender::rolling::daily("/logs", "log_test.log");
let (non_blocking_appender, _guard) = tracing_appender::non_blocking(appender);
tracing_subscriber::fmt().with_writer(non_blocking_appender).with_ansi(false).init();
info!("logging info!");

Output:

2023-07-13T09:48:10.321104Z  INFO logging: logging info!

I want to customize the message with a [year-month-day hour:minute:seconds] timestamp instead. I've tried both the event_format and with_timer, but if I use them, the init() method is not longer available:

let timer = time::format_description::parse("[year]-[month padding:zero]-[day padding:zero] [hour]:[minute]:[second]").expect("Cataplum");
let timer_format = fmt::format().with_timer(timer);
let subscriber = tracing_subscriber::fmt().with_writer(non_blocking_appender).with_timer(timer_format);

Is there an easy way for format this message?

Answer 1

You can set a time format this way:

let timer = time::format_description::parse(
    "[year]-[month padding:zero]-[day padding:zero] [hour]:[minute]:[second]",
)
.expect("Cataplum");
let time_offset =
    time::UtcOffset::current_local_offset().unwrap_or_else(|_| time::UtcOffset::UTC);
let timer = fmt::time::OffsetTime::new(time_offset, timer);
let subscriber = tracing_subscriber::fmt()
    .with_write(non_blocking_appender)
    .with_timer(timer)
    .init();