func (r defaultNetworkResolver) GetDefaultNetwork() (boshsettings.Network, error) {
	network := boshsettings.Network{}

	routes, err := r.routesSearcher.SearchRoutes()
	if err != nil {
		return network, bosherr.WrapError(err, "Searching routes")
	}

	if len(routes) == 0 {
		return network, bosherr.Error("No routes found")
	}

	for _, route := range routes {
		if !route.IsDefault() {
			continue
		}

		ip, err := r.ipResolver.GetPrimaryIPv4(route.InterfaceName)
		if err != nil {
			return network, bosherr.WrapErrorf(err, "Getting primary IPv4 for interface '%s'", route.InterfaceName)
		}

		return boshsettings.Network{
			IP:      ip.IP.String(),
			Netmask: gonet.IP(ip.Mask).String(),
			Gateway: route.Gateway,
		}, nil

	}

	return network, bosherr.Error("Failed to find default route")
}

func (r concreteRunner) Run(action Action, payloadBytes []byte) (value interface{}, err error) {
	payloadArgs, err := r.extractJSONArguments(payloadBytes)
	if err != nil {
		err = bosherr.WrapError(err, "Extracting json arguments")
		return
	}

	actionValue := reflect.ValueOf(action)
	runMethodValue := actionValue.MethodByName("Run")
	if runMethodValue.Kind() != reflect.Func {
		err = bosherr.Error("Run method not found")
		return
	}

	runMethodType := runMethodValue.Type()
	if r.invalidReturnTypes(runMethodType) {
		err = bosherr.Error("Run method should return a value and an error")
		return
	}

	methodArgs, err := r.extractMethodArgs(runMethodType, payloadArgs)
	if err != nil {
		err = bosherr.WrapError(err, "Extracting method arguments from payload")
		return
	}

	values := runMethodValue.Call(methodArgs)
	return r.extractReturns(values)
}

func (f SettingsSourceFactory) buildWithoutRegistry() (boshsettings.Source, error) {
	var settingsSources []boshsettings.Source

	for _, opts := range f.options.Sources {
		var settingsSource boshsettings.Source

		switch typedOpts := opts.(type) {
		case HTTPSourceOptions:
			return nil, bosherr.Error("HTTP source is not supported without registry")

		case ConfigDriveSourceOptions:
			settingsSource = NewConfigDriveSettingsSource(
				typedOpts.DiskPaths,
				typedOpts.MetaDataPath,
				typedOpts.SettingsPath,
				f.platform,
				f.logger,
			)

		case FileSourceOptions:
			return nil, bosherr.Error("File source is not supported without registry")

		case CDROMSourceOptions:
			settingsSource = NewCDROMSettingsSource(
				typedOpts.FileName,
				f.platform,
				f.logger,
			)
		}

		settingsSources = append(settingsSources, settingsSource)
	}

	return NewMultiSettingsSource(settingsSources...)
}

func (a DrainAction) determineParams(drainType DrainType, currentSpec boshas.V1ApplySpec, newSpecs []boshas.V1ApplySpec) (boshdrain.ScriptParams, error) {
	var newSpec *boshas.V1ApplySpec
	var params boshdrain.ScriptParams

	if len(newSpecs) > 0 {
		newSpec = &newSpecs[0]
	}

	switch drainType {
	case DrainTypeStatus:
		// Status was used in the past when dynamic drain was implemented in the Director.
		// Now that we implement it in the agent, we should never get a call for this type.
		return params, bosherr.Error("Unexpected call with drain type 'status'")

	case DrainTypeUpdate:
		if newSpec == nil {
			return params, bosherr.Error("Drain update requires new spec")
		}

		params = boshdrain.NewUpdateParams(currentSpec, *newSpec)

	case DrainTypeShutdown:
		err := a.notifier.NotifyShutdown()
		if err != nil {
			return params, bosherr.WrapError(err, "Notifying shutdown")
		}

		params = boshdrain.NewShutdownParams(currentSpec, newSpec)
	}

	return params, nil
}

func (p linux) findRootDevicePath() (string, error) {
	mounts, err := p.diskManager.GetMountsSearcher().SearchMounts()

	if err != nil {
		return "", bosherr.WrapError(err, "Searching mounts")
	}

	for _, mount := range mounts {
		if mount.MountPoint == "/" && strings.HasPrefix(mount.PartitionPath, "/dev/") {
			p.logger.Debug(logTag, "Found root partition: `%s'", mount.PartitionPath)

			stdout, _, _, err := p.cmdRunner.RunCommand("readlink", "-f", mount.PartitionPath)
			if err != nil {
				return "", bosherr.WrapError(err, "Shelling out to readlink")
			}
			rootPartition := strings.Trim(stdout, "\n")
			p.logger.Debug(logTag, "Symlink is: `%s'", rootPartition)

			validRootPartition := regexp.MustCompile(`^/dev/[a-z]+1$`)
			if !validRootPartition.MatchString(rootPartition) {
				return "", bosherr.Error("Root partition is not the first partition")
			}

			return strings.Trim(rootPartition, "1"), nil
		}
	}

	return "", bosherr.Error("Getting root partition device")
}

func (bc FileBundleCollection) Get(definition BundleDefinition) (Bundle, error) {
	if len(definition.BundleName()) == 0 {
		return nil, bosherr.Error("Missing bundle name")
	}

	if len(definition.BundleVersion()) == 0 {
		return nil, bosherr.Error("Missing bundle version")
	}

	installPath := filepath.Join(bc.installPath, bc.name, definition.BundleName(), definition.BundleVersion())
	enablePath := filepath.Join(bc.enablePath, bc.name, definition.BundleName())
	return NewFileBundle(installPath, enablePath, bc.fs, bc.logger), nil
}

func (b localBlobstore) Validate() error {
	path, found := b.options["blobstore_path"]
	if !found {
		return bosherr.Error("missing blobstore_path")
	}

	_, ok := path.(string)
	if !ok {
		return bosherr.Error("blobstore_path must be a string")
	}

	return nil
}

func (b retryableBlobstore) Validate() error {
	if b.maxTries < 1 {
		return bosherr.Error("Max tries must be > 0")
	}

	return b.blobstore.Validate()
}

func (udev ConcreteUdevDevice) readByte(filePath string) error {
	udev.logger.Debug(udev.logtag, "readBytes from file: %s", filePath)
	device, err := os.Open(filePath)
	if err != nil {
		return err
	}
	defer func() {
		if err = device.Close(); err != nil {
			udev.logger.Warn(udev.logtag, "Failed to close device: %s", err.Error())
		}
	}()
	udev.logger.Debug(udev.logtag, "Successfully open file: %s", filePath)

	bytes := make([]byte, 1, 1)
	read, err := device.Read(bytes)
	if err != nil {
		return err
	}
	udev.logger.Debug(udev.logtag, "Successfully read %d bytes from file: %s", read, filePath)

	if read != 1 {
		return bosherr.Error("Device readable but zero length")
	}

	return nil
}

func (b FileBundle) GetInstallPath() (boshsys.FileSystem, string, error) {
	path := b.installPath
	if !b.fs.FileExists(path) {
		return nil, "", bosherr.Error("install dir does not exist")
	}

	return b.fs, path, nil
}

func (ms *configDriveMetadataService) GetInstanceID() (string, error) {
	if ms.metaDataContents.InstanceID == "" {
		return "", bosherr.Error("Failed to load instance-id from config drive metadata service")
	}

	ms.logger.Debug(ms.logTag, "Getting instance id: %s", ms.metaDataContents.InstanceID)
	return ms.metaDataContents.InstanceID, nil
}

func (ms *configDriveMetadataService) GetServerName() (string, error) {
	if ms.userDataContents.Server.Name == "" {
		return "", bosherr.Error("Failed to load server name from config drive metadata service")
	}

	ms.logger.Debug(ms.logTag, "Getting server name: %s", ms.userDataContents.Server.Name)
	return ms.userDataContents.Server.Name, nil
}

func (ms *configDriveMetadataService) GetPublicKey() (string, error) {
	if firstPublicKey, ok := ms.metaDataContents.PublicKeys["0"]; ok {
		if openSSHKey, ok := firstPublicKey["openssh-key"]; ok {
			return openSSHKey, nil
		}
	}

	return "", bosherr.Error("Failed to load openssh-key from config drive metadata service")
}

func NewMultiSettingsSource(sources ...boshsettings.Source) (boshsettings.Source, error) {
	var err error

	if len(sources) == 0 {
		err = bosherr.Error("MultiSettingsSource requires to have at least one source")
	}

	return &MultiSettingsSource{sources: sources}, err
}

func (d *dummyNatsJobSupervisor) Start() error {
	if d.status == "fail_task" {
		return bosherror.Error("fake-task-fail-error")
	}
	if d.status != "failing" {
		d.status = "running"
	}
	return nil
}

func (r concreteRunner) extractReturns(values []reflect.Value) (value interface{}, err error) {
	errValue := values[1]
	if !errValue.IsNil() {
		errorValues := errValue.MethodByName("Error").Call([]reflect.Value{})
		err = bosherr.Error(errorValues[0].String())
	}

	value = values[0].Interface()
	return
}

func BuildErrorWithJSON(msg string, logger boshlog.Logger) ([]byte, error) {
	response := NewExceptionResponse(bosherr.Error(msg))

	respJSON, err := json.Marshal(response)
	if err != nil {
		return respJSON, bosherr.WrapError(err, "Marshalling JSON")
	}

	logger.Info(mbusHandlerLogTag, "Building error", msg)

	return respJSON, nil
}

func (udev ConcreteUdevDevice) Trigger() (err error) {
	udev.logger.Debug(udev.logtag, "Triggering UdevDevice")
	switch {
	case udev.runner.CommandExists("udevadm"):
		_, _, _, err = udev.runner.RunCommand("udevadm", "trigger")
	case udev.runner.CommandExists("udevtrigger"):
		_, _, _, err = udev.runner.RunCommand("udevtrigger")
	default:
		err = bosherr.Error("can not find udevadm or udevtrigger commands")
	}
	return
}

func (ms httpMetadataService) GetServerName() (string, error) {
	userData, err := ms.getUserData()
	if err != nil {
		return "", bosherr.WrapError(err, "Getting user data")
	}

	serverName := userData.Server.Name

	if len(serverName) == 0 {
		return "", bosherr.Error("Empty server name")
	}

	return serverName, nil
}

func (d *Downloader) httpClient() (*http.Client, error) {
	certPool := x509.NewCertPool()
	if !certPool.AppendCertsFromPEM(([]byte)(d.config.CACertPem)) {
		return nil, errors.Error("Failed to load CA cert")
	}

	tr := &http.Transport{
		TLSClientConfig: &tls.Config{
			RootCAs:    certPool,
			ClientAuth: tls.RequireAndVerifyClientCert,
		},
	}

	return &http.Client{Transport: tr}, nil
}