func (dd *DNSDiscovery) refresh(name string, ch chan<- config.TargetGroup) error {
	response, err := lookupAll(name, dd.qtype)
	dnsSDLookupsCount.Inc()
	if err != nil {
		dnsSDLookupFailuresCount.Inc()
		return err
	}

	var tg config.TargetGroup
	for _, record := range response.Answer {
		target := model.LabelValue("")
		switch addr := record.(type) {
		case *dns.SRV:
			// Remove the final dot from rooted DNS names to make them look more usual.
			addr.Target = strings.TrimRight(addr.Target, ".")

			target = model.LabelValue(fmt.Sprintf("%s:%d", addr.Target, addr.Port))
		case *dns.A:
			target = model.LabelValue(fmt.Sprintf("%s:%d", addr.A, dd.port))
		case *dns.AAAA:
			target = model.LabelValue(fmt.Sprintf("%s:%d", addr.AAAA, dd.port))
		default:
			log.Warnf("%q is not a valid SRV record", record)
			continue

		}
		tg.Targets = append(tg.Targets, model.LabelSet{
			model.AddressLabel: target,
			dnsNameLabel:       model.LabelValue(name),
		})
	}

	tg.Source = name
	ch <- tg

	return nil
}

func (e *Endpoints) addServiceLabels(ns, name string, tg *config.TargetGroup) {
	svc := &apiv1.Service{}
	svc.Namespace = ns
	svc.Name = name

	obj, exists, err := e.serviceStore.Get(svc)
	if !exists || err != nil {
		return
	}
	if err != nil {
		e.logger.With("err", err).Errorln("retrieving service failed")
	}
	svc = obj.(*apiv1.Service)

	tg.Labels = tg.Labels.Merge(serviceLabels(svc))
}

func (srv *consulService) watch(ctx context.Context, ch chan<- []*config.TargetGroup) {
	catalog := srv.client.Catalog()

	lastIndex := uint64(0)
	for {
		nodes, meta, err := catalog.Service(srv.name, "", &consul.QueryOptions{
			WaitIndex: lastIndex,
			WaitTime:  watchTimeout,
		})
		// Check the context before potentially falling in a continue-loop.
		select {
		case <-ctx.Done():
			return
		default:
			// Continue.
		}

		if err != nil {
			log.Errorf("Error refreshing service %s: %s", srv.name, err)
			time.Sleep(retryInterval)
			continue
		}
		// If the index equals the previous one, the watch timed out with no update.
		if meta.LastIndex == lastIndex {
			continue
		}
		lastIndex = meta.LastIndex

		tgroup := config.TargetGroup{
			Source:  srv.name,
			Labels:  srv.labels,
			Targets: make([]model.LabelSet, 0, len(nodes)),
		}

		for _, node := range nodes {

			// We surround the separated list with the separator as well. This way regular expressions
			// in relabeling rules don't have to consider tag positions.
			var tags = srv.tagSeparator + strings.Join(node.ServiceTags, srv.tagSeparator) + srv.tagSeparator

			// If the service address is not empty it should be used instead of the node address
			// since the service may be registered remotely through a different node
			var addr string
			if node.ServiceAddress != "" {
				addr = net.JoinHostPort(node.ServiceAddress, fmt.Sprintf("%d", node.ServicePort))
			} else {
				addr = net.JoinHostPort(node.Address, fmt.Sprintf("%d", node.ServicePort))
			}

			tgroup.Targets = append(tgroup.Targets, model.LabelSet{
				model.AddressLabel:  model.LabelValue(addr),
				addressLabel:        model.LabelValue(node.Address),
				nodeLabel:           model.LabelValue(node.Node),
				tagsLabel:           model.LabelValue(tags),
				serviceAddressLabel: model.LabelValue(node.ServiceAddress),
				servicePortLabel:    model.LabelValue(strconv.Itoa(node.ServicePort)),
				serviceIDLabel:      model.LabelValue(node.ServiceID),
			})
		}
		// Check context twice to ensure we always catch cancelation.
		select {
		case <-ctx.Done():
			return
		default:
		}
		select {
		case <-ctx.Done():
			return
		case ch <- []*config.TargetGroup{&tgroup}:
		}
	}
}