func (ep *endpoint) buildHostsFiles() error {
	var extraContent []etchosts.Record

	ep.Lock()
	container := ep.container
	joinInfo := ep.joinInfo
	ifaces := ep.iFaces
	ep.Unlock()

	if container == nil {
		return ErrNoContainer{}
	}

	if container.config.hostsPath == "" {
		container.config.hostsPath = defaultPrefix + "/" + container.id + "/hosts"
	}

	dir, _ := filepath.Split(container.config.hostsPath)
	err := createBasePath(dir)
	if err != nil {
		return err
	}

	if joinInfo != nil && joinInfo.hostsPath != "" {
		content, err := ioutil.ReadFile(joinInfo.hostsPath)
		if err != nil && !os.IsNotExist(err) {
			return err
		}

		if err == nil {
			return ioutil.WriteFile(container.config.hostsPath, content, 0644)
		}
	}

	name := container.config.hostName
	if container.config.domainName != "" {
		name = name + "." + container.config.domainName
	}

	for _, extraHost := range container.config.extraHosts {
		extraContent = append(extraContent,
			etchosts.Record{Hosts: extraHost.name, IP: extraHost.IP})
	}

	IP := ""
	if len(ifaces) != 0 && ifaces[0] != nil {
		IP = ifaces[0].addr.IP.String()
	}

	return etchosts.Build(container.config.hostsPath, IP, container.config.hostName,
		container.config.domainName, extraContent)
}

func (sb *sandbox) updateHostsFile(ifaceIP string, svcRecords []etchosts.Record) error {
	// Rebuild the hosts file accounting for the passed interface IP and service records
	extraContent := make([]etchosts.Record, 0, len(sb.config.extraHosts)+len(svcRecords))

	for _, extraHost := range sb.config.extraHosts {
		extraContent = append(extraContent, etchosts.Record{Hosts: extraHost.name, IP: extraHost.IP})
	}

	for _, svc := range svcRecords {
		extraContent = append(extraContent, svc)
	}

	return etchosts.Build(sb.config.hostsPath, ifaceIP, sb.config.hostName, sb.config.domainName, extraContent)
}

func (sb *sandbox) updateHostsFile(ifaceIP string, svcRecords []etchosts.Record) error {
	var err error

	if sb.config.originHostsPath != "" {
		return nil
	}

	max := func(a, b int) int {
		if a < b {
			return b
		}

		return a
	}

	extraContent := make([]etchosts.Record, 0,
		max(len(sb.config.extraHosts), len(svcRecords)))

	sb.hostsOnce.Do(func() {
		// Rebuild the hosts file accounting for the passed
		// interface IP and service records

		for _, extraHost := range sb.config.extraHosts {
			extraContent = append(extraContent,
				etchosts.Record{Hosts: extraHost.name, IP: extraHost.IP})
		}

		err = etchosts.Build(sb.config.hostsPath, ifaceIP,
			sb.config.hostName, sb.config.domainName, extraContent)
	})

	if err != nil {
		return err
	}

	extraContent = extraContent[:0]
	for _, svc := range svcRecords {
		extraContent = append(extraContent, svc)
	}

	sb.addHostsEntries(extraContent)
	return nil
}