config

Config Package

Environment variable configuration loader with struct tag support and default values.

Features

• Load environment variables into Go structs using reflection
• Support for default values via struct tags
• Type conversion for string, int, int64, and bool fields
• Simple, zero-dependency implementation

Usage

Basic Example

package main

import (
    "fmt"
    "github.com/gobeaver/beaver-kit/config"
)

type AppConfig struct {
    DatabaseURL string `env:"DATABASE_URL,default:postgres://localhost/myapp"`
    Port        int    `env:"PORT,default:8080"`
    Debug       bool   `env:"DEBUG,default:false"`
}

func main() {
    cfg := &AppConfig{}
    if err := config.Load(cfg); err != nil {
        panic(err)
    }
    
    fmt.Printf("Database: %s\n", cfg.DatabaseURL)
    fmt.Printf("Port: %d\n", cfg.Port)
    fmt.Printf("Debug: %t\n", cfg.Debug)
}

Environment Variables

DATABASE_URL=postgres://prod-server/myapp
PORT=3000
DEBUG=true

Struct Tag Format

type Config struct {
    Field string `env:"ENV_VAR_NAME,default:defaultvalue"`
}

• ENV_VAR_NAME: Environment variable to read from
• default:value: Optional default value if environment variable is not set

Supported Types

• string: Direct assignment
• int and int64: Parsed using strconv.ParseInt
• bool: Parsed using strconv.ParseBool (accepts: true, false, 1, 0, t, f, TRUE, FALSE, True, False)

Package Integration Pattern

Many packages use this config pattern for initialization:

package mypackage

type Config struct {
    APIKey string `env:"MYPACKAGE_API_KEY"`
    Host   string `env:"MYPACKAGE_HOST,default:localhost"`
    Port   int    `env:"MYPACKAGE_PORT,default:8080"`
}

func GetConfig() *Config {
    cfg := &Config{}
    config.Load(cfg)
    return cfg
}

Implementation

The config.Load() function uses reflection to:

1. Iterate through struct fields
2. Read env tags to get environment variable names and defaults
3. Load values from environment or use defaults
4. Convert string values to appropriate field types