commons

README

Commons Library

A collection of common Go utilities for building production applications.

Features

Logger

A structured logging wrapper around go.uber.org/zap that provides:

• JSON formatted output with ISO8601 timestamps
• Configurable log levels (debug, info, warn, error, fatal)
• Environment variable configuration via LOG_LEVEL
• Runtime log level changes
• Caller information in logs

Installation

go get github.com/jbjoret/commons

Usage

Logger Package

Basic Usage

package main

import (
    "github.com/jbjoret/commons/logger"
    "go.uber.org/zap"
)

func main() {
    // Optional: Initialize from environment (reads LOG_LEVEL env var)
    logger.Init()

    // Log at different levels
    logger.Debug("Debug information", zap.Int("count", 42))
    logger.Info("Application started", zap.String("version", "1.0"))
    logger.Warn("Warning message", zap.String("component", "api"))
    logger.Error("Error occurred", zap.Error(err))

    // Fatal logs and exits
    logger.Fatal("Critical error", zap.String("reason", "startup failed"))
}

Setting Log Level

From Environment Variable:

# Set before running your application
export LOG_LEVEL=debug
go run main.go

Programmatically:

// Change log level at runtime
if err := logger.SetLogLevel("debug"); err != nil {
    logger.Error("Failed to set log level", zap.Error(err))
}

// Get current log level
level := logger.GetLogLevel()
logger.Info("Current log level", zap.String("level", level))

Supported Log Levels

• debug - Detailed information for diagnosing problems
• info - General informational messages (default)
• warn or warning - Warning messages
• error - Error messages
• dpanic - Development panic (panics in development, logs in production)
• panic - Logs and then panics
• fatal - Logs and then calls os.Exit(1)

Example Output

{
  "level": "info",
  "timestamp": "2026-01-16T11:37:53.965+0100",
  "caller": "main.go:15",
  "msg": "Application started",
  "version": "1.0"
}

Development

Building

make target

Running Tests

make test

Formatting Code

make fmt

Updating Dependencies

make update

Requirements

• Go 1.26 or higher
• Dependencies are managed via Go modules

License

See LICENSE file for details.