Go Logging Package

This Go package provides a customizable logging solution with colored terminal output and structured logging for non-terminal outputs. It is designed to work seamlessly across Windows, macOS (Darwin), and Linux, leveraging the log/slog package with platform-specific enhancements.

Features

• Colored Terminal Output: Log levels like [DEBUG], [INFO] are color-coded (blue, green, yellow, red) when output is a terminal.
• Structured Logging: Clean structured logs with a level_str attribute when redirected to files or other non-terminal outputs.
• Cross-Platform Support:
  • Windows: Enables ANSI escape codes.
  • macOS/Linux: Uses native ANSI support.
• Configurable Output: Supports any io.Writer (e.g., os.Stdout, os.Stderr, or a file).
• Robust Error Handling: Returns errors on configuration/logging failures.
• Safe Log Level Handling: Gracefully handles unknown/custom levels with fallback formatting.

Installation

Requires Go 1.21 or later:

go get github.com/yourusername/logging
go get golang.org/x/term

Replace github.com/yourusername/logging with the actual import path.

Usage

package main

import (
	"fmt"
	"os"
	"log/slog"

	"github.com/yourusername/logging"
)

func main() {
	if err := logging.ConfigureLogging(os.Stdout); err != nil {
		fmt.Fprintf(os.Stderr, "Failed to configure logging: %v\n", err)
		os.Exit(1)
	}

	slog.Debug("This is a debug message")
	slog.Info("This is an info message")
	slog.Warn("This is a warning message")
	slog.Error("This is an error message")
}

Example Output

Terminal (Windows/macOS/Linux):

[DEBUG] This is a debug message   // in blue
[INFO]  This is an info message   // in green
[WARN]  This is a warning message // in yellow
[ERROR] This is an error message  // in red

Redirected to a File:

time=2025-06-06T14:20:00Z level=DEBUG level_str=[DEBUG] msg="This is a debug message"
time=2025-06-06T14:20:00Z level=INFO  level_str=[INFO]  msg="This is an info message"
time=2025-06-06T14:20:00Z level=WARN  level_str=[WARN]  msg="This is a warning message"
time=2025-06-06T14:20:00Z level=ERROR level_str=[ERROR] msg="This is an error message"

Customizing Output

You can direct logs to a file:

package main

import (
	"fmt"
	"os"
	"log/slog"

	"github.com/yourusername/logging"
)

func main() {
	file, err := os.Create("app.log")
	if err != nil {
		fmt.Fprintf(os.Stderr, "Failed to create log file: %v\n", err)
		os.Exit(1)
	}
	defer file.Close()

	if err := logging.ConfigureLogging(file); err != nil {
		fmt.Fprintf(os.Stderr, "Failed to configure logging: %v\n", err)
		os.Exit(1)
	}

	slog.Info("Logging to a file")
}

Platform-Specific Notes

• Windows: Uses golang.org/x/sys/windows to enable ANSI color support.
• macOS/Linux: Relies on native terminal support for ANSI color codes.
• Uses Go build tags (//go:build windows, //go:build darwin || linux) for platform-specific implementations.

Dependencies

• Standard library: log/slog, os, fmt, io, context
• golang.org/x/term
• golang.org/x/sys/windows (Windows only)

Building and Testing

go build ./...
go test ./...

Test on all supported platforms to validate both colored terminal output and structured log files.