code: func readCredentialSpecRegistry(id, name string) (string, error) {
  	key, err := registryOpenKeyFunc(registry.LOCAL_MACHINE, credentialSpecRegistryLocation, registry.QUERY_VALUE)
  	if err != nil {
  		return "", errors.Wrapf(err, "failed handling spec %q for container %s - registry key %s could not be opened", name, id, credentialSpecRegistryLocation)
  	}
  	defer key.Close()
  
  	value, _, err := key.GetStringValue(name)
  	if err != nil {
  		if err == registry.ErrNotExist {
  			return "", fmt.Errorf("registry credential spec %q for container %s was not found", name, id)
  		}
  		return "", errors.Wrapf(err, "error reading credential spec %q from registry for container %s", name, id)
  	}
  
  	return value, nil
  }
docs: // readCredentialSpecRegistry is a helper function to read a credential spec from
  // the registry. If not found, we return an empty string and warn in the log.
  // This allows for staging on machines which do not have the necessary components.