code: func decodeDockerConfigFieldAuth(field string) (username, password string, err error) {
  	decoded, err := base64.StdEncoding.DecodeString(field)
  	if err != nil {
  		return
  	}
  
  	parts := strings.SplitN(string(decoded), ":", 2)
  	if len(parts) != 2 {
  		err = fmt.Errorf("unable to parse auth field")
  		return
  	}
  
  	username = parts[0]
  	password = parts[1]
  
  	return
  }
docs: // decodeDockerConfigFieldAuth deserializes the "auth" field from dockercfg into a
  // username and a password. The format of the auth field is base64(<username>:<password>).