minimal_logger

A minimal-resource, multi-platform logger for Rust applications with optional file output, automatic flushing, and log rotation support.

Features

Thread-local buffered logging with BufWriter
Platform-specific log rotation support
- Linux/macOS: SIGHUP
- Windows: Global\\RustLogger_LogRotate event
Periodic flush thread with configurable interval
Environment-driven configuration for log level, output file, buffer size, and format
Falls back to stderr when file output is unavailable

Getting started

Add minimal_logger as a dependency and initialise it once at startup:

use log::{error, info};

fn main() {
    minimal_logger::init().expect("failed to initialise logger");

    info!("application started");
    error!("shutdown due to error");

    minimal_logger::shutdown();
}

Configuration

The logger reads configuration from environment variables.

Variable	Default	Description
`RUST_LOG`	`info`	Global level and per-target filters
`RUST_LOG_FILE`	`stderr`	Absolute path to log file; if unset, logs go to `stderr`
`RUST_LOG_BUFFER_SIZE`	`4096`	Per-thread buffer capacity in bytes
`RUST_LOG_FLUSH_MS`	`1000`	Periodic flush interval in milliseconds
`RUST_LOG_FORMAT`	`"{timestamp} [{level:<5}] T[{thread_name}] [{file}:{line}] {args}"`	Log message format template (timestamp is fixed 6-digit microseconds)

Supported format fields:

timestamp
level
thread_name
target
module_path
file
line
args

Rotation support

The logger can reopen its log file on demand using platform-native rotation signals:

Unix-like systems: SIGHUP
Windows: Global\\RustLogger_LogRotate named event

When rotation is triggered, existing thread-local buffers flush to the old file and new writes move to the reopened file.

Cargo metadata