Slogx

A structured logging library for Go, built on top of slog with automatic log rotation, environment awareness, and flexible configuration.

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Features

• Built on Go 1.21+ slog package
• Automatic log rotation (powered by lumberjack)
• JSON and text output formats
• Auto-naming log files based on program name
• Environment-aware configuration (test/production)
• Environment variables support
• Console and file output support
• Dynamic log level adjustment via signals
• Structured logging with field support

Installation

go get github.com/luojiego/slogx

Quick Start

package main

import (
    "fmt"
    slogx "github.com/luojiego/slogx"
)

func main() {
    // Use package-level functions
    slogx.Info("Application started")
    slogx.Debug("Debug information")
    slogx.Error("Error occurred", "error", fmt.Errorf("321"))

    // Use With to add extra fields
    logger := slogx.With("module", "user-service")
    logger.Info("User logged in", "userId", 123)
}

Configuration

Default Settings

• Log file location: ./logs/<program-name>.log
• Log level: Debug
• Output format: Text
• Single log file size: 50MB
• Number of backup files: 100
• Log retention days: 30 days

Environment Variables

Configure logging behavior through environment variables:

Variable	Description	Default
LOG_MAX_SIZE	Maximum size of each log file (MB)	50
LOG_MAX_BACKUPS	Maximum number of old log files	100
LOG_MAX_AGE	Days to retain old log files	30
GO_ENV	Runtime environment (production/prod for production)	-

Environment-Specific Behavior

Test Environment (Default):

• Outputs to both console and file
• No compression for old log files

Production Environment (GO_ENV=production/prod):

• File output only
• Automatic compression for old log files

Custom Configuration

Use NewLogger function for custom configuration:

logger := slogx.NewLogger(slogx.Config{
    Level:      "debug",
    Format:     "json",
    Filename:   "custom.log",
    MaxSize:    100,    // MB
    MaxBackups: 10,     // number of files
    MaxAge:     7,      // days
    Compress:   true,   // compress old files
    Stdout:     true,   // console output
})

// Set as default logger (optional)
slogx.SetDefaultLogger(logger)

Dynamic Log Level Adjustment

Adjust log levels at runtime using system signals:

• SIGHUP: Set to Debug level
• SIGUSR1: Set to Info level
• SIGUSR2: Set to Warn level

Example (Unix/Linux):

# Switch to Debug level
kill -HUP <pid>

# Switch to Info level
kill -USR1 <pid>

# Switch to Warn level
kill -USR2 <pid>

Dependencies

• Go 1.21+
• gopkg.in/natefinch/lumberjack.v2

License

MIT License

Contributing

Issues and Pull Requests are welcome!

Author

luojiego