my-log/config/load.go

package config

import (
	"bytes"
	"context"
	"fmt"
	"strings"

	"github.com/spf13/viper"
)

type confKeyType uint8

const (
	_ confKeyType = iota
	viperKey
)

func RetrieveFromContext(ctx context.Context) (*viper.Viper, Config) {
	v, ok := ctx.Value(viperKey).(*viper.Viper)
	if !ok {
		panic("config not found in context")
	}
	var c Config
	if err := v.Unmarshal(&c); err != nil {
		panic(fmt.Errorf("failed to unmarshal config: %w", err))
	}
	return v, c
}

func AddToContext(ctx context.Context, v *viper.Viper) context.Context {
	return context.WithValue(ctx, viperKey, v)
}

func New(ctx context.Context) (context.Context, *viper.Viper, error) {
	v := viper.New()
	v.SetConfigType("toml")

	if err := v.ReadConfig(bytes.NewBufferString(DefaultStr())); err != nil {
		return ctx, nil, err
	}

	v.SetConfigFile(DefaultPath())
	v.SetEnvPrefix("MYLOG")
	v.AutomaticEnv()
	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_", "-", "_"))

	if err := v.ReadInConfig(); err != nil {
		return ctx, nil, err
	}

	return AddToContext(ctx, v), v, nil
}