config.go

package config

import (
   "fmt"
   "log"
   "os"
   "path"
   "path/filepath"
   "runtime"

   "github.com/spf13/viper"
)

type config struct {
   AppEnv   string
   Database struct {
      User                 string
      Password             string
      Net                  string
      Addr                 string
      DBName               string
      AllowNativePasswords bool
      Params               struct {
         ParseTime string
         Charset   string
         Loc       string
         TLS       string
      }
   }
}

// C is config variable
var C config

// Application Environment name
const (
   Development = "development"
   Staging     = "staging"
   Production  = "production"
)

// ReadConfigOption is a config option
type ReadConfigOption struct {
   AppEnv string
}

// ReadConfig configures config file
func ReadConfig(option ReadConfigOption) {
   Config := &C

   e := appEnv(option)

   if e == Staging {
     setStaging()
   } else if e == Production {
     setProd()
   } else {
     setDev()
   }

   viper.SetConfigType("yml")
   viper.AutomaticEnv()

   if err := viper.ReadInConfig(); err != nil {
      fmt.Println(err)
      log.Fatalln(err)
   }

   if err := viper.Unmarshal(&Config); err != nil {
      fmt.Println(err)
      os.Exit(1)
   }
}

func appEnv(option ReadConfigOption) string {
   if option.AppEnv != "" {
      return option.AppEnv
   }
   if os.Getenv("APP_ENV") != "" {
      return os.Getenv("APP_ENV")
   }

   return Development
}

func rootDir() string {
   _, b, _, _ := runtime.Caller(0)
   d := path.Join(path.Dir(b))
   return filepath.Dir(d)
}

func setDev() {
   viper.AddConfigPath(filepath.Join(rootDir(), "config"))
   viper.SetConfigName("config")
}

func setStaging() {
   viper.AddConfigPath(filepath.Join(rootDir(), "config"))
   viper.SetConfigName("config.staging")
}

func setProd() {
   viper.AddConfigPath(filepath.Join(rootDir(), "config"))
   viper.SetConfigName("config.production")
}