Adding `ftail` library as a dependency

Run this command in a terminal, in your project's directory:

cargo add ftail

To add it manually, edit your project's Cargo.toml file and add to the [dependencies] section:

ftail = "0.3.1"

The ftail library will be automatically available globally. Read the ftail library documentation.

Back to the crate overview.

Readme

Ftail

Ftail is a simple logging implementation for the log crate with support for multiple channels, including console output, files, and custom loggers.

Features

Multiple logging channels: console, formatted console, single file, daily file, and custom
Level and target filtering
Optional timestamp formatting and timezone support
Automatic log rotation and retention
Use RUST_LOG environment variable for dynamic log level control (use '_env_level' postfix)

Quick Start

Add Ftail to your Cargo.toml:

[dependencies]
ftail = "0.3"

Initialize Ftail in your main.rs or lib.rs:

use ftail::Ftail;
use log::LevelFilter;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    Ftail::new()
        .console(LevelFilter::Info)        // log to console
        .daily_file("logs", LevelFilter::Error) // log errors to daily files
        .init()?; // initialize logger

    log::info!("Hello, Ftail!");
    log::error!("This is an error message");
    Ok(())
}

Configuration Options

Option	Description	Notes
`.datetime_format()`	Set the datetime format	Ex: `"%Y-%m-%d %H:%M:%S%.3f"`
`.timezone()`	Set the timezone	Requires `timezone` feature
`.max_file_size()`	Maximum file size in MB	Older logs renamed `.old{N}`
`.retention_days()`	Number of days to keep log files	Daily file only
`.filter_levels()`	Log only the specified levels	`Vec<Level>`
`.filter_targets()`	Log only the specified targets	`Vec<&str>`

Channels

Console

Logs to the standard output without formatting.

Ftail::new()
    .console(LevelFilter::Trace)
    .init()?;

Output:

2024-09-13 17:35:18 TRACE console This is a trace message
2024-09-13 17:35:18 DEBUG console This is a debug message
2024-09-13 17:35:18 INFO foo bar
2024-09-13 17:35:18 WARN console This is a warning message
2024-09-13 17:35:18 ERROR console This is an error message

Formatted Console

Logs with formatted and colored output.

Ftail::new()
    .formatted_console(LevelFilter::Trace)
    .init()?;

Output:

2024-09-13 17:35:37 · TRACE
This is a trace message
examples/formatted_console/src/main.rs:9

2024-09-13 17:35:37 · DEBUG
This is a debug message
examples/formatted_console/src/main.rs:11

Single File

Logs to a single file (e.g., logs/demo.log).

Ftail::new()
    .single_file(Path::new("logs/demo.log"), true, LevelFilter::Trace)
    .init()?;

append = true keeps existing logs, false overwrites.

Daily File

Logs to daily files in a directory (e.g., logs/2025-09-25.log).

Ftail::new()
    .daily_file(Path::new("logs"), LevelFilter::Trace)
    .init()?;

Automatically rotates files per day.

Custom Channel

Create your own logger by implementing the log::Log trait:

Ftail::new()
    .custom(
        |config| Box::new(CustomLogger { config }) as Box<dyn Log + Send + Sync>,
        LevelFilter::Debug,
    )
    .datetime_format("%H:%M:%S%.3f")
    .init()?;

struct CustomLogger {
    config: ftail::Config,
}

impl log::Log for CustomLogger {
    fn enabled(&self, metadata: &log::Metadata) -> bool {
        metadata.level() <= self.config.level_filter
    }

    fn log(&self, record: &log::Record) {
        if !self.enabled(record.metadata()) {
            return;
        }
        let time = chrono::Local::now()
            .format(&self.config.datetime_format)
            .to_string();
        println!("[{}] {}: {}", time, record.level(), record.args());
    }

    fn flush(&self) {}
}

Output:

19:37:22.402 [DEBUG] This is a debug message
19:37:22.403 [INFO] bar
19:37:22.403 [WARN] This is a warning message
19:37:22.403 [ERROR] This is an error message

Tips

Use .console(LevelFilter::Debug) for development.
Use .daily_file() in production to organize logs by date.
Combine .max_file_size() and .retention_days() to prevent disk bloat.
Only enable the channels you need to reduce overhead by disabling default features in Cargo.toml.

Adding ftail library as a dependency

Adding `ftail` library as a dependency