ESL_Logger

This module provides an interface for logging messages with different severity levels: DEBUG, INFO, WARN, ERROR and FATAL. Messages can be logged to standard output or to a file.

Usage

First, create a new instance of Logger:

logger := ESL_Logger.NewLogger("DevLogger", "development")
// or
logger := ESL_Logger.NewLogger("ProdLogger", "production", "app.log")

You can log messages with different severity levels:

logger.Debug("This is a debug message")
logger.Info("This is an info message")
logger.Warn("This is a warning message")
logger.Error("This is an error message")
logger.Fatal("This is a fatal message")

Customizing the Logger's Format

To customize the logger's format, modify the Format field in the Config struct when creating a new logger instance. The placeholders in the format string are:

• %s for the timestamp
• %s for the logger name
• %s for the severity level
• %s for the actual log message

config := &ESL_Logger.Config{
    Name:       "CustomLogger",
    Output:     "stdout", // or "app.log" to log to a file
    Format:     "[%s] %s - %s: %s", // Custom format: [timestamp] logger_name - severity: message
    MaxSize:    10, // maximum file size in megabytes
    MaxBackups: 3,  // maximum number of backup files
    MaxAge:     30, // maximum number of days to retain backup files
}

logger := ESL_Logger.NewLogger(config)

Colored Logs

Log messages are colored based on their severity level:

• DEBUG messages are colored in Cyan
• INFO messages are colored in Blue
• WARN messages are colored in Yellow
• ERROR messages are colored in Red
• FATAL messages are colored in Purple

Environment-Specific Configuration

You can specify different configurations for different environments. For example, you can log messages to a file in the production environment and to standard output in the development environment.

logger := ESL_Logger.NewLogger("DevLogger", "development")
// or
logger := ESL_Logger.NewLogger("ProdLogger", "production", "app.log")

Configuration

The logger can be configured using the Config struct. The following fields can be set:

type Config struct {
    Name       string // Name of the logger
    Output     string // Output destination: "stdout" or "app.log"
    Format     string // Format of the log message
    MaxSize    int    // Maximum file size in megabytes
    MaxBackups int    // Maximum number of backup files
    MaxAge     int    // Maximum number of days to retain backup files
}