Snowlog

A structured logging library for Rust that outputs logs in JSON format with support for log rotation, multiple writers, and global logging.

Features

• Structured Logging: Logs are structured as JSON objects with fields like service name, level, message, timestamp, and payload.
• Log Levels: Supports Debug, Info, Warn, Error levels with filtering.
• Writers:
  • ConsoleWriter: Outputs to stdout.
  • RotationWriter: Writes to files with automatic rotation based on line count.
  • MultiWriter: Combines multiple writers for simultaneous output.
• Global Logger: Uses OnceLock for thread-safe global configuration.

Installation

Add this to your Cargo.toml:

[dependencies]
rogger = "0.1.0"
serde_json = "1.0"  # For JSON payloads

Usage

Basic Setup

use rogger::{Logger, LogLevel, ConsoleWriter};

fn main() {
    // Initialize the global logger
    let writer = Box::new(ConsoleWriter);
    Logger::init(LogLevel::Info, "my_app".to_string(), writer);

    // Log messages
    Logger::info("Application started", serde_json::json!({"version": "1.0"}));
    Logger::error("An error occurred", serde_json::json!({"error_code": 500}));
}

Using File Rotation

use rogger::RotationWriter;
use std::path::Path;

let writer = Box::new(RotationWriter::new(
    Path::new("./logs"),
    "app.log".to_string(),
    1000,  // Max lines per file
));
Logger::init(LogLevel::Debug, "my_app".to_string(), writer);

Multiple Writers

use rogger::{MultiWriter, ConsoleWriter, RotationWriter};

let multi_writer = Box::new(MultiWriter::new());
multi_writer.add_writer(Box::new(ConsoleWriter));
multi_writer.add_writer(Box::new(RotationWriter::new(
    Path::new("./logs"),
    "app.log".to_string(),
    1000,
)));
Logger::init(LogLevel::Info, "my_app".to_string(), multi_writer);

Log Levels

• LogLevel::Debug
• LogLevel::Info
• LogLevel::Warn
• LogLevel::Error

Logs below the set level are filtered out.

API

Logger

• Logger::init(level: LogLevel, service: String, writer: Box<dyn Writer + Send>): Initialize the global logger.
• Logger::debug(message: &str, payload: serde_json::Value)
• Logger::info(message: &str, payload: serde_json::Value)
• Logger::warn(message: &str, payload: serde_json::Value)
• Logger::error(message: &str, payload: serde_json::Value)

Writers

All writers implement the Writer trait.

• ConsoleWriter: Prints to stdout.
• RotationWriter::new(path: &Path, base_filename: String, max_lines: usize): Rotates files when max_lines is reached.
• MultiWriter::new() + add_writer(writer: Box<dyn Writer>): Combines writers.

LogEntry

Represents a log entry. Can be serialized to JSON.

let entry = LogEntry::new("service".to_string(), "info".to_string(), "message".to_string(), payload, None);
let json = entry.to_json_string().unwrap();

License

MPL-2.0