Multi file writer not working for logging to both file and io::stdout

[hyc3z]

Bug Report

Version

tracing = "0.1.35"
tracing-appender = "0.2.2"
tracing-subscriber = "0.3.14"

tracing v0.1.35
│ │ │ │ ├── tracing-attributes v0.1.22 (proc-macro)
│ │ │ │ └── tracing-core v0.1.28
│ │ │ └── tracing v0.1.35 ()
│ │ ├── tracing v0.1.35 ()
│ │ └── tracing v0.1.35 ()
│ │ └── tracing v0.1.35 ()
│ ├── tracing v0.1.35 ()
├── tracing v0.1.35 ()
├── tracing-appender v0.2.2
│ └── tracing-subscriber v0.3.14
│ ├── tracing-core v0.1.28 ()
│ └── tracing-log v0.1.3
│ └── tracing-core v0.1.28 ()
├── tracing-subscriber v0.3.14 (*)

Platform

macos 12.4 monterey

Crates

Description

In the main function:

let file_appender = tracing_appender::rolling::never("./logs", "log.log");

tracing_subscriber::fmt()
    .with_writer(file_appender)
    .with_ansi(false)
    .with_max_level(tracing::Level::TRACE)
    .init();

Above works, the log successfully outputs to log file.
However, when adding an additional writer to std::io::stdout, the log will only appear in the terminal, not in the file.

let file_appender = tracing_appender::rolling::never("./logs", "log.log");

tracing_subscriber::fmt()
    .with_writer(file_appender)
    .with_writer(std::io::stdout)
    .with_ansi(false)
    .with_max_level(tracing::Level::TRACE)
    .init();

When I follow the example here:
https://github.com/tokio-rs/tracing/blob/master/examples/examples/appender-multifile.rs

I get the following output:

no method named `and` found for struct `tracing_appender::rolling::RollingFileAppender` in the current scope

[davidbarsky]

However, when adding an additional writer to std::io::stdout, the log will only appear in the terminal, not in the file.

In this example below this sentence, you're replacing the file_appender writer with the std::io::stdout writer, which explains the behavior you're seeing.

When I follow the example here:
https://github.com/tokio-rs/tracing/blob/master/examples/examples/appender-multifile.rs

Do you have use tracing_subscriber::fmt::writer::MakeWriterExt; at the top of your file? The .and combinator is defined on that extension trait.

[hyc3z]

Thanks a lot for your response!
I tried and added
use tracing_subscriber::fmt::writer::MakeWriterExt;
and it is now logging to both file and stdout.

[davidbarsky]

glad to hear that it's working now!