Struct Logger 

pub struct Logger { /* private fields */ }

Builder for initializing the global tracing subscriber.

Uses a fluent builder pattern to configure log level, output format, and optional environment-based filtering before calling init.

Examples

Minimal setup (text output at INFO level):

use tiny_tracing::Logger;

Logger::new().init().unwrap();
tiny_tracing::info!("Ready");

JSON output with environment filter:

use tiny_tracing::{Logger, LogFormat, Level};

Logger::new()
    .with_level(Level::DEBUG)
    .with_format(LogFormat::Json)
    .with_env_filter("info,my_crate=trace")
    .init()
    .unwrap();

Implementations

impl Logger

pub fn new() -> Self

Creates a new Logger with default values.

Defaults: Level::INFO, LogFormat::Text, no env filter, file location off, target on, output to stdout.

Examples found in repository

examples/basic.rs (line 8)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    Logger::new().init()?;

    info!("hello from tiny-tracing");
    Ok(())
}

examples/file.rs (line 11)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    Logger::new()
        .with_output(Output::Both("app.log".into()))
        .init()?;

    info!("this line goes to both stdout and app.log");
    warn!(file = "app.log", "check the file for a colour-free copy");
    Ok(())
}

examples/json.rs (line 8)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    Logger::new()
        .with_level(Level::DEBUG)
        .with_format(LogFormat::Json)
        .with_file(true)
        .init()?;

    info!(user_id = 42, action = "login", "structured event");
    warn!("something worth a second look");
    Ok(())
}

examples/env_filter.rs (line 11)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let filter = std::env::var("RUST_LOG").unwrap_or_else(|_| "info,env_filter=debug".to_string());

    Logger::new().with_env_filter(filter).init()?;

    info!("info line — always visible");
    debug!("debug line — visible when this crate is at DEBUG or lower");
    trace!("trace line — needs RUST_LOG=trace or similar");
    Ok(())
}

pub fn with_level(self, level: Level) -> Self

Sets the global (default) log level.

This is the base level applied to every target. Per-target directives passed to with_env_filter refine it on top — the level is never silently ignored. A global directive inside the env filter string (e.g. the info in "info,my_crate=debug") does take precedence over this value.

Examples found in repository

examples/json.rs (line 9)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    Logger::new()
        .with_level(Level::DEBUG)
        .with_format(LogFormat::Json)
        .with_file(true)
        .init()?;

    info!(user_id = 42, action = "login", "structured event");
    warn!("something worth a second look");
    Ok(())
}

pub fn with_format(self, format: LogFormat) -> Self

Sets the output format.

Examples found in repository

examples/json.rs (line 10)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    Logger::new()
        .with_level(Level::DEBUG)
        .with_format(LogFormat::Json)
        .with_file(true)
        .init()?;

    info!(user_id = 42, action = "login", "structured event");
    warn!("something worth a second look");
    Ok(())
}

pub fn with_env_filter(self, filter: impl Into<String>) -> Self

Adds environment-based, per-target filtering via EnvFilter.

The directives here are layered on top of the global with_level value. Supported syntax: "info", "info,my_crate=debug", etc.

If not called, only the static with_level value applies.

Examples found in repository

examples/env_filter.rs (line 11)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let filter = std::env::var("RUST_LOG").unwrap_or_else(|_| "info,env_filter=debug".to_string());

    Logger::new().with_env_filter(filter).init()?;

    info!("info line — always visible");
    debug!("debug line — visible when this crate is at DEBUG or lower");
    trace!("trace line — needs RUST_LOG=trace or similar");
    Ok(())
}

pub fn with_file(self, enabled: bool) -> Self

Controls whether the source file name appears in log lines.

Disabled by default.

Examples found in repository

examples/json.rs (line 11)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    Logger::new()
        .with_level(Level::DEBUG)
        .with_format(LogFormat::Json)
        .with_file(true)
        .init()?;

    info!(user_id = 42, action = "login", "structured event");
    warn!("something worth a second look");
    Ok(())
}

pub fn with_target(self, enabled: bool) -> Self

Controls whether the module path (target) appears in log lines.

Enabled by default.

pub fn with_output(self, output: Output) -> Self

Sets where log lines are written: stdout, a file, or both.

Defaults to Output::Stdout. When a file is involved it is opened in append mode (created if missing) and writes are synchronised, so the call stays panic-free — an unopenable path yields LoggerError::OpenLogFile from init.

Examples found in repository

examples/file.rs (line 12)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    Logger::new()
        .with_output(Output::Both("app.log".into()))
        .init()?;

    info!("this line goes to both stdout and app.log");
    warn!(file = "app.log", "check the file for a colour-free copy");
    Ok(())
}

pub fn level(&self) -> Level

Returns the configured log level.

pub fn format(&self) -> LogFormat

Returns the configured output format.

pub fn init(self) -> Result<(), LoggerError>

Initializes the global tracing subscriber.

Consumes the builder. Must be called only once per process; subsequent calls return LoggerError::TryInitError.

Errors

• LoggerError::InvalidEnvFilter if an env filter was set and EnvFilter rejects it.
• LoggerError::OpenLogFile if a file output was requested but the path could not be opened for writing.
• LoggerError::TryInitError if a global subscriber is already set.

Examples found in repository

examples/basic.rs (line 8)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    Logger::new().init()?;

    info!("hello from tiny-tracing");
    Ok(())
}

examples/file.rs (line 13)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    Logger::new()
        .with_output(Output::Both("app.log".into()))
        .init()?;

    info!("this line goes to both stdout and app.log");
    warn!(file = "app.log", "check the file for a colour-free copy");
    Ok(())
}

examples/json.rs (line 12)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    Logger::new()
        .with_level(Level::DEBUG)
        .with_format(LogFormat::Json)
        .with_file(true)
        .init()?;

    info!(user_id = 42, action = "login", "structured event");
    warn!("something worth a second look");
    Ok(())
}

examples/env_filter.rs (line 11)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let filter = std::env::var("RUST_LOG").unwrap_or_else(|_| "info,env_filter=debug".to_string());

    Logger::new().with_env_filter(filter).init()?;

    info!("info line — always visible");
    debug!("debug line — visible when this crate is at DEBUG or lower");
    trace!("trace line — needs RUST_LOG=trace or similar");
    Ok(())
}

Trait Implementations

impl Default for Logger

fn default() -> Self

Returns the “default value” for a type.