config

Config Package

The config package provides a reusable and extensible configuration loader built on top of Viper. It is designed to simplify configuration management in Go applications by supporting multiple config sources, context propagation, and functional loading options.

Features

• Environment-First Configuration: Automatically reads from environment variables.
• YAML File Support: Load config from .yaml files (required or optional).
• Injectable Defaults: Provide fallback values when env or file values are not present.
• Context Integration: Easily inject and retrieve config via context.Context or *http.Request.

Usage

This is the simplest way to get started using MustConfig with some defaults:

package main

import (
	"fmt"

	"github.com/kittipat1413/go-common/framework/config"
)

func main() {
	cfg := config.MustConfig(
        config.WithRequiredConfigPath("env.yaml"),
		config.WithDefaults(map[string]any{
			"SERVICE_NAME": "my-service",
			"SERVICE_PORT": ":8080",
			"ENV":          "development",
		}),
	)

	// Read config values
	serviceName := cfg.GetString("SERVICE_NAME")
	port := cfg.GetString("SERVICE_PORT")
	env := cfg.GetString("ENV")

	fmt.Println("=== Service Config ===")
	fmt.Printf("Service Name: %s\n", serviceName)
	fmt.Printf("Port:         %s\n", port)
	fmt.Printf("Environment:  %s\n", env)
}

With an optional env.yaml override:

SERVICE_NAME: "user-api"
SERVICE_PORT: ":9090"
ENV: "staging"

Examples

• You can find a complete working example in the repository under framework/config/example.

Functional Options

WithRequiredConfigPath(path string): Fails if the file does not exist or is unreadable.

config.WithRequiredConfigPath("env.yaml")

WithOptionalConfigPaths(path string): Tries each path in order and uses the first found file. Skips missing files.

config.WithOptionalConfigPaths("env.yaml")

WithDefaults(defaults map[string]any): Injects fallback values if the config key is not set in env or file.

config.WithDefaults(map[string]any{
    "SERVICE_NAME": "my-service",
    "SERVICE_PORT": ":8080",
    "ENV":          "development",
})

Accessing Values

cfg.Get("SERVICE_NAME")           // any type
cfg.GetString("SERVICE_NAME")     // string
cfg.GetInt("MAX_WORKERS")         // int
cfg.GetDuration("TIMEOUT")        // string, use time.ParseDuration
cfg.All()                         // map[string]interface{}