code: func NewDNSProvider() (*DNSProvider, error) {
  	_, err := env.Get("OS_AUTH_URL", "OS_USERNAME", "OS_PASSWORD", "OS_TENANT_NAME", "OS_REGION_NAME")
  	if err != nil {
  		return nil, fmt.Errorf("designate: %v", err)
  	}
  
  	opts, err := openstack.AuthOptionsFromEnv()
  	if err != nil {
  		return nil, fmt.Errorf("designate: %v", err)
  	}
  
  	config := NewDefaultConfig()
  	config.opts = opts
  
  	return NewDNSProviderConfig(config)
  }
docs: // NewDNSProvider returns a DNSProvider instance configured for Designate.
  // Credentials must be passed in the environment variables:
  // OS_AUTH_URL, OS_USERNAME, OS_PASSWORD, OS_TENANT_NAME, OS_REGION_NAME.