func NewDiscovery(cfg *SDConfig, logger log.Logger) *Discovery {
	if logger == nil {
		logger = log.NewNopLogger()
	}
	d := &Discovery{
		cfg:    cfg,
		port:   cfg.Port,
		logger: logger,
	}
	d.Discovery = refresh.NewDiscovery(
		logger,
		"azure",
		time.Duration(cfg.RefreshInterval),
		d.refresh,
	)
	return d
}
func NewDiscovery(cfg *SDConfig, logger log.Logger) *Discovery {
	if logger == nil {
		logger = log.NewNopLogger()
	}
	d := &Discovery{
		cfg:    cfg,
		port:   cfg.Port,
		logger: logger,
	}
	d.Discovery = refresh.NewDiscovery(
		logger,
		"azure",
		time.Duration(cfg.RefreshInterval),
		d.refresh,
	)
	return d
}
// NewDiscovery returns a new AzureDiscovery which periodically refreshes its targets.