package main import ( "errors" "fmt" // "github.com/davecgh/go-spew/spew" "log" "os" "strconv" ) type ConfigEntry struct { Type string Ptr interface{} Values []string } type TrelloConfig struct { Url string Token string } type SmtpConfig struct { Hostname string Port uint16 Username string Password string AuthType string SecurityType string } type EmailConfig struct { From string To string Subject string } type Config struct { Email EmailConfig Smtp SmtpConfig Trello TrelloConfig } func NewConfig() *Config { return &Config{} } func (config *Config) ParseEnv() (int, error) { // map env variables to config pointers dataMap := map[string](ConfigEntry){ "EMAIL_FROM": ConfigEntry{"string", &(config.Email.From), nil}, "EMAIL_TO": ConfigEntry{"string", &(config.Email.To), nil}, "EMAIL_SUBJECT": ConfigEntry{"string", &(config.Email.Subject), nil}, "TRELLO_URL": ConfigEntry{"string", &(config.Trello.Url), nil}, "TRELLO_TOKEN": ConfigEntry{"string", &(config.Trello.Token), nil}, "SMTP_HOSTNAME": ConfigEntry{"string", &(config.Smtp.Hostname), nil}, "SMTP_USERNAME": ConfigEntry{"string", &(config.Smtp.Username), nil}, "SMTP_PASSWORD": ConfigEntry{"string", &(config.Smtp.Password), nil}, "SMTP_PORT": ConfigEntry{"uint16", &(config.Smtp.Port), nil}, "SMTP_AUTH_TYPE": ConfigEntry{"string", &(config.Smtp.AuthType), []string{"none", "plain", "login"}}, "SMTP_SECURITY_TYPE": ConfigEntry{"string", &(config.Smtp.SecurityType), []string{"none", "tls", "starttls"}}, } for envVar, mapEntry := range dataMap { envValue := os.Getenv(envVar) if len(envValue) == 0 { errmsg := fmt.Sprintf( "Empty environment variable. Please set %s value", envVar, ) log.Panic(errors.New(errmsg)) } if mapEntry.Values != nil { allowedValue := false for _, v := range mapEntry.Values { if v == envValue { allowedValue = true } } if !allowedValue { errmsg := fmt.Sprintf( "Wrong value for %s=%s. Value must be one of %v", envVar, envValue, mapEntry.Values, ) log.Panic(errors.New(errmsg)) } } switch mapEntry.Type { case "string": *(mapEntry.Ptr.(*string)) = envValue case "uint16": u64, err := strconv.ParseUint(envValue, 10, 16) if err != nil { errmsg := fmt.Sprintf( "Unable to convert %s=%s to unsigned int", envVar, envValue, ) log.Panic(errors.New(errmsg)) } *(mapEntry.Ptr.(*uint16)) = uint16(u64) case "bool": b, err := strconv.ParseBool(envValue) if err != nil { errmsg := fmt.Sprintf( "Unable to convert %s=%s to boolean", envVar, envValue, ) log.Panic(errors.New(errmsg)) } *(mapEntry.Ptr.(*bool)) = b default: errmsg := fmt.Sprintf( "Undefined parser for %s<%s>", envVar, mapEntry.Type, ) log.Panic(errors.New(errmsg)) } } // spew.Dump(config) return 0, nil }