heetch/confitaのサンプル

config.go

package config

import (
	"context"
	"os"
	"path/filepath"
	"strings"

	"github.com/heetch/confita"
	"github.com/heetch/confita/backend"
	"github.com/heetch/confita/backend/file"
)

type ServerConfig struct {
	Port int `config:"port"`
}

// デフォルトのenv.Backendだと微妙だったので、コピペして持ってきてprefixをつけるようなbackendを自前で書いてる
func yataiboneEnvBackend() backend.Backend {
	return backend.Func("yataibone-env", func(ctx context.Context, key string) ([]byte, error) {
		if val := os.Getenv(key); val != "" {
			return []byte(val), nil
		}
		key = strings.Replace(strings.ToUpper("YATAIBONE_"+key), "-", "_", -1)
		if val := os.Getenv(key); val != "" {
			return []byte(val), nil
		}
		return nil, backend.ErrNotFound
	})
}

func ReadServerConfig() (*ServerConfig, error) {
	var bs []backend.Backend = []backend.Backend{
		file.NewOptionalBackend("/etc/yataibone/config.yml"),
	}
	if home, err := os.UserHomeDir(); err == nil {
		bs = append(bs, file.NewOptionalBackend(filepath.Join(home, ".yataibone", "config.yml")))
	}
	if wd, err := os.Getwd(); err == nil {
		bs = append(bs, file.NewOptionalBackend(filepath.Join(wd, "yataibone.yml")))
	}
	bs = append(bs, yataiboneEnvBackend())
	l := confita.NewLoader(bs...)
	c := ServerConfig{
		Port: 8080,
	}
	err := l.Load(context.Background(), &c)
	if err != nil {
		return nil, err
	}
	return &c, nil
}