k3s/pkg/volume/csi/csi_plugin.go

/*
Copyright 2017 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package csi

import (
	"errors"
	"fmt"
	"os"
	"path"
	"sort"
	"strings"
	"time"

	"context"

	"k8s.io/klog"

	api "k8s.io/api/core/v1"
	apierrs "k8s.io/apimachinery/pkg/api/errors"
	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/types"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	utilversion "k8s.io/apimachinery/pkg/util/version"
	"k8s.io/apimachinery/pkg/util/wait"
	utilfeature "k8s.io/apiserver/pkg/util/feature"
	csiapiinformer "k8s.io/client-go/informers"
	csiinformer "k8s.io/client-go/informers/storage/v1beta1"
	clientset "k8s.io/client-go/kubernetes"
	csilister "k8s.io/client-go/listers/storage/v1beta1"
	csitranslationplugins "k8s.io/csi-translation-lib/plugins"
	"k8s.io/kubernetes/pkg/features"
	"k8s.io/kubernetes/pkg/volume"
	"k8s.io/kubernetes/pkg/volume/csi/nodeinfomanager"
)

const (
	// CSIPluginName is the name of the in-tree CSI Plugin
	CSIPluginName = "kubernetes.io/csi"

	// TODO (vladimirvivien) implement a more dynamic way to discover
	// the unix domain socket path for each installed csi driver.
	// TODO (vladimirvivien) would be nice to name socket with a .sock extension
	// for consistency.
	csiAddrTemplate = "/var/lib/kubelet/plugins/%v/csi.sock"
	csiTimeout      = 15 * time.Second
	volNameSep      = "^"
	volDataFileName = "vol_data.json"
	fsTypeBlockName = "block"

	// TODO: increase to something useful
	csiResyncPeriod = time.Minute
)

var deprecatedSocketDirVersions = []string{"0.1.0", "0.2.0", "0.3.0", "0.4.0"}

type csiPlugin struct {
	host              volume.VolumeHost
	blockEnabled      bool
	csiDriverLister   csilister.CSIDriverLister
	csiDriverInformer csiinformer.CSIDriverInformer
}

// ProbeVolumePlugins returns implemented plugins
func ProbeVolumePlugins() []volume.VolumePlugin {
	p := &csiPlugin{
		host:         nil,
		blockEnabled: utilfeature.DefaultFeatureGate.Enabled(features.CSIBlockVolume),
	}
	return []volume.VolumePlugin{p}
}

// volume.VolumePlugin methods
var _ volume.VolumePlugin = &csiPlugin{}

// RegistrationHandler is the handler which is fed to the pluginwatcher API.
type RegistrationHandler struct {
}

// TODO (verult) consider using a struct instead of global variables
// csiDrivers map keep track of all registered CSI drivers on the node and their
// corresponding sockets
var csiDrivers = &DriversStore{}

var nim nodeinfomanager.Interface

// PluginHandler is the plugin registration handler interface passed to the
// pluginwatcher module in kubelet
var PluginHandler = &RegistrationHandler{}

// ValidatePlugin is called by kubelet's plugin watcher upon detection
// of a new registration socket opened by CSI Driver registrar side car.
func (h *RegistrationHandler) ValidatePlugin(pluginName string, endpoint string, versions []string, foundInDeprecatedDir bool) error {
	klog.Infof(log("Trying to validate a new CSI Driver with name: %s endpoint: %s versions: %s, foundInDeprecatedDir: %v",
		pluginName, endpoint, strings.Join(versions, ","), foundInDeprecatedDir))

	if foundInDeprecatedDir {
		// CSI 0.x drivers used /var/lib/kubelet/plugins as the socket dir.
		// This was deprecated as the socket dir for kubelet drivers, in lieu of a dedicated dir /var/lib/kubelet/plugins_registry
		// The deprecated dir will only be allowed for a whitelisted set of old versions.
		// CSI 1.x drivers should use the /var/lib/kubelet/plugins_registry
		if !isDeprecatedSocketDirAllowed(versions) {
			err := fmt.Errorf("socket for CSI driver %q versions %v was found in a deprecated dir. Drivers implementing CSI 1.x+ must use the new dir", pluginName, versions)
			klog.Error(err)
			return err
		}
	}

	_, err := h.validateVersions("ValidatePlugin", pluginName, endpoint, versions)
	return err
}

// RegisterPlugin is called when a plugin can be registered
func (h *RegistrationHandler) RegisterPlugin(pluginName string, endpoint string, versions []string) error {
	klog.Infof(log("Register new plugin with name: %s at endpoint: %s", pluginName, endpoint))

	highestSupportedVersion, err := h.validateVersions("RegisterPlugin", pluginName, endpoint, versions)
	if err != nil {
		return err
	}

	// Storing endpoint of newly registered CSI driver into the map, where CSI driver name will be the key
	// all other CSI components will be able to get the actual socket of CSI drivers by its name.
	csiDrivers.Set(pluginName, Driver{
		endpoint:                endpoint,
		highestSupportedVersion: highestSupportedVersion,
	})

	// Get node info from the driver.
	csi, err := newCsiDriverClient(csiDriverName(pluginName))
	if err != nil {
		return err
	}

	ctx, cancel := context.WithTimeout(context.Background(), csiTimeout)
	defer cancel()

	driverNodeID, maxVolumePerNode, accessibleTopology, err := csi.NodeGetInfo(ctx)
	if err != nil {
		if unregErr := unregisterDriver(pluginName); unregErr != nil {
			klog.Error(log("registrationHandler.RegisterPlugin failed to unregister plugin due to previous error: %v", unregErr))
		}
		return err
	}

	err = nim.InstallCSIDriver(pluginName, driverNodeID, maxVolumePerNode, accessibleTopology)
	if err != nil {
		if unregErr := unregisterDriver(pluginName); unregErr != nil {
			klog.Error(log("registrationHandler.RegisterPlugin failed to unregister plugin due to previous error: %v", unregErr))
		}
		return err
	}

	return nil
}

func (h *RegistrationHandler) validateVersions(callerName, pluginName string, endpoint string, versions []string) (*utilversion.Version, error) {
	if len(versions) == 0 {
		err := fmt.Errorf("%s for CSI driver %q failed. Plugin returned an empty list for supported versions", callerName, pluginName)
		klog.Error(err)
		return nil, err
	}

	// Validate version
	newDriverHighestVersion, err := highestSupportedVersion(versions)
	if err != nil {
		err := fmt.Errorf("%s for CSI driver %q failed. None of the versions specified %q are supported. err=%v", callerName, pluginName, versions, err)
		klog.Error(err)
		return nil, err
	}

	existingDriver, driverExists := csiDrivers.Get(pluginName)
	if driverExists {
		if !existingDriver.highestSupportedVersion.LessThan(newDriverHighestVersion) {
			err := fmt.Errorf("%s for CSI driver %q failed. Another driver with the same name is already registered with a higher supported version: %q", callerName, pluginName, existingDriver.highestSupportedVersion)
			klog.Error(err)
			return nil, err
		}
	}

	return newDriverHighestVersion, nil
}

// DeRegisterPlugin is called when a plugin removed its socket, signaling
// it is no longer available
func (h *RegistrationHandler) DeRegisterPlugin(pluginName string) {
	klog.V(4).Info(log("registrationHandler.DeRegisterPlugin request for plugin %s", pluginName))
	if err := unregisterDriver(pluginName); err != nil {
		klog.Error(log("registrationHandler.DeRegisterPlugin failed: %v", err))
	}
}

func (p *csiPlugin) Init(host volume.VolumeHost) error {
	p.host = host

	if utilfeature.DefaultFeatureGate.Enabled(features.CSIDriverRegistry) {
		csiClient := host.GetKubeClient()
		if csiClient == nil {
			return errors.New("unable to get Kubernetes client")
		}
		// Start informer for CSIDrivers.
		factory := csiapiinformer.NewSharedInformerFactory(csiClient, csiResyncPeriod)
		p.csiDriverInformer = factory.Storage().V1beta1().CSIDrivers()
		p.csiDriverLister = p.csiDriverInformer.Lister()
		go factory.Start(wait.NeverStop)
	}

	var migratedPlugins = map[string](func() bool){
		csitranslationplugins.GCEPDInTreePluginName: func() bool {
			return utilfeature.DefaultFeatureGate.Enabled(features.CSIMigration) && utilfeature.DefaultFeatureGate.Enabled(features.CSIMigrationGCE)
		},
		csitranslationplugins.AWSEBSInTreePluginName: func() bool {
			return utilfeature.DefaultFeatureGate.Enabled(features.CSIMigration) && utilfeature.DefaultFeatureGate.Enabled(features.CSIMigrationAWS)
		},
		csitranslationplugins.CinderInTreePluginName: func() bool {
			return utilfeature.DefaultFeatureGate.Enabled(features.CSIMigration) && utilfeature.DefaultFeatureGate.Enabled(features.CSIMigrationOpenStack)
		},
	}

	// Initializing the label management channels
	nim = nodeinfomanager.NewNodeInfoManager(host.GetNodeName(), host, migratedPlugins)

	if utilfeature.DefaultFeatureGate.Enabled(features.CSINodeInfo) &&
		utilfeature.DefaultFeatureGate.Enabled(features.CSIMigration) {
		// This function prevents Kubelet from posting Ready status until CSINodeInfo
		// is both installed and initialized
		if err := initializeCSINode(host); err != nil {
			return fmt.Errorf("failed to initialize CSINodeInfo: %v", err)
		}
	}

	return nil
}

func initializeCSINode(host volume.VolumeHost) error {
	kvh, ok := host.(volume.KubeletVolumeHost)
	if !ok {
		klog.V(4).Info("Cast from VolumeHost to KubeletVolumeHost failed. Skipping CSINodeInfo initialization, not running on kubelet")
		return nil
	}
	kubeClient := host.GetKubeClient()
	if kubeClient == nil {
		// Kubelet running in standalone mode. Skip CSINodeInfo initialization
		klog.Warning("Skipping CSINodeInfo initialization, kubelet running in standalone mode")
		return nil
	}

	kvh.SetKubeletError(errors.New("CSINodeInfo is not yet initialized"))

	go func() {
		defer utilruntime.HandleCrash()

		// Backoff parameters tuned to retry over 140 seconds. Will fail and restart the Kubelet
		// after max retry steps.
		initBackoff := wait.Backoff{
			Steps:    6,
			Duration: 15 * time.Millisecond,
			Factor:   6.0,
			Jitter:   0.1,
		}
		err := wait.ExponentialBackoff(initBackoff, func() (bool, error) {
			klog.V(4).Infof("Initializing migrated drivers on CSINodeInfo")
			err := nim.InitializeCSINodeWithAnnotation()
			if err != nil {
				kvh.SetKubeletError(fmt.Errorf("Failed to initialize CSINodeInfo: %v", err))
				klog.Errorf("Failed to initialize CSINodeInfo: %v", err)
				return false, nil
			}

			// Successfully initialized drivers, allow Kubelet to post Ready
			kvh.SetKubeletError(nil)
			return true, nil
		})
		if err != nil {
			// 2 releases after CSIMigration and all CSIMigrationX (where X is a volume plugin)
			// are permanently enabled the apiserver/controllers can assume that the kubelet is
			// using CSI for all Migrated volume plugins. Then all the CSINode initialization
			// code can be dropped from Kubelet.
			// Kill the Kubelet process and allow it to restart to retry initialization
			klog.Fatalf("Failed to initialize CSINodeInfo after retrying")
		}
	}()
	return nil
}

func (p *csiPlugin) GetPluginName() string {
	return CSIPluginName
}

// GetvolumeName returns a concatenated string of CSIVolumeSource.Driver<volNameSe>CSIVolumeSource.VolumeHandle
// That string value is used in Detach() to extract driver name and volumeName.
func (p *csiPlugin) GetVolumeName(spec *volume.Spec) (string, error) {
	csi, err := getCSISourceFromSpec(spec)
	if err != nil {
		klog.Error(log("plugin.GetVolumeName failed to extract volume source from spec: %v", err))
		return "", err
	}

	// return driverName<separator>volumeHandle
	return fmt.Sprintf("%s%s%s", csi.Driver, volNameSep, csi.VolumeHandle), nil
}

func (p *csiPlugin) CanSupport(spec *volume.Spec) bool {
	// TODO (vladimirvivien) CanSupport should also take into account
	// the availability/registration of specified Driver in the volume source
	return spec.PersistentVolume != nil && spec.PersistentVolume.Spec.CSI != nil
}

func (p *csiPlugin) IsMigratedToCSI() bool {
	return false
}

func (p *csiPlugin) RequiresRemount() bool {
	return false
}

func (p *csiPlugin) NewMounter(
	spec *volume.Spec,
	pod *api.Pod,
	_ volume.VolumeOptions) (volume.Mounter, error) {
	pvSource, err := getCSISourceFromSpec(spec)
	if err != nil {
		return nil, err
	}
	readOnly, err := getReadOnlyFromSpec(spec)
	if err != nil {
		return nil, err
	}

	k8s := p.host.GetKubeClient()
	if k8s == nil {
		klog.Error(log("failed to get a kubernetes client"))
		return nil, errors.New("failed to get a Kubernetes client")
	}

	csi, err := newCsiDriverClient(csiDriverName(pvSource.Driver))
	if err != nil {
		return nil, err
	}

	mounter := &csiMountMgr{
		plugin:       p,
		k8s:          k8s,
		spec:         spec,
		pod:          pod,
		podUID:       pod.UID,
		driverName:   csiDriverName(pvSource.Driver),
		volumeID:     pvSource.VolumeHandle,
		specVolumeID: spec.Name(),
		csiClient:    csi,
		readOnly:     readOnly,
	}

	// Save volume info in pod dir
	dir := mounter.GetPath()
	dataDir := path.Dir(dir) // dropoff /mount at end

	if err := os.MkdirAll(dataDir, 0750); err != nil {
		klog.Error(log("failed to create dir %#v:  %v", dataDir, err))
		return nil, err
	}
	klog.V(4).Info(log("created path successfully [%s]", dataDir))

	// persist volume info data for teardown
	node := string(p.host.GetNodeName())
	attachID := getAttachmentName(pvSource.VolumeHandle, pvSource.Driver, node)
	volData := map[string]string{
		volDataKey.specVolID:    spec.Name(),
		volDataKey.volHandle:    pvSource.VolumeHandle,
		volDataKey.driverName:   pvSource.Driver,
		volDataKey.nodeName:     node,
		volDataKey.attachmentID: attachID,
	}

	if err := saveVolumeData(dataDir, volDataFileName, volData); err != nil {
		klog.Error(log("failed to save volume info data: %v", err))
		if err := os.RemoveAll(dataDir); err != nil {
			klog.Error(log("failed to remove dir after error [%s]: %v", dataDir, err))
			return nil, err
		}
		return nil, err
	}

	klog.V(4).Info(log("mounter created successfully"))

	return mounter, nil
}

func (p *csiPlugin) NewUnmounter(specName string, podUID types.UID) (volume.Unmounter, error) {
	klog.V(4).Infof(log("setting up unmounter for [name=%v, podUID=%v]", specName, podUID))

	unmounter := &csiMountMgr{
		plugin:       p,
		podUID:       podUID,
		specVolumeID: specName,
	}

	// load volume info from file
	dir := unmounter.GetPath()
	dataDir := path.Dir(dir) // dropoff /mount at end
	data, err := loadVolumeData(dataDir, volDataFileName)
	if err != nil {
		klog.Error(log("unmounter failed to load volume data file [%s]: %v", dir, err))
		return nil, err
	}
	unmounter.driverName = csiDriverName(data[volDataKey.driverName])
	unmounter.volumeID = data[volDataKey.volHandle]
	unmounter.csiClient, err = newCsiDriverClient(unmounter.driverName)
	if err != nil {
		return nil, err
	}

	return unmounter, nil
}

func (p *csiPlugin) ConstructVolumeSpec(volumeName, mountPath string) (*volume.Spec, error) {
	klog.V(4).Info(log("plugin.ConstructVolumeSpec [pv.Name=%v, path=%v]", volumeName, mountPath))

	volData, err := loadVolumeData(mountPath, volDataFileName)
	if err != nil {
		klog.Error(log("plugin.ConstructVolumeSpec failed loading volume data using [%s]: %v", mountPath, err))
		return nil, err
	}

	klog.V(4).Info(log("plugin.ConstructVolumeSpec extracted [%#v]", volData))

	fsMode := api.PersistentVolumeFilesystem
	pv := &api.PersistentVolume{
		ObjectMeta: meta.ObjectMeta{
			Name: volData[volDataKey.specVolID],
		},
		Spec: api.PersistentVolumeSpec{
			PersistentVolumeSource: api.PersistentVolumeSource{
				CSI: &api.CSIPersistentVolumeSource{
					Driver:       volData[volDataKey.driverName],
					VolumeHandle: volData[volDataKey.volHandle],
				},
			},
			VolumeMode: &fsMode,
		},
	}

	return volume.NewSpecFromPersistentVolume(pv, false), nil
}

func (p *csiPlugin) SupportsMountOption() bool {
	// TODO (vladimirvivien) use CSI VolumeCapability.MountVolume.mount_flags
	// to probe for the result for this method
	// (bswartz) Until the CSI spec supports probing, our only option is to
	// make plugins register their support for mount options or lack thereof
	// directly with kubernetes.
	return true
}

func (p *csiPlugin) SupportsBulkVolumeVerification() bool {
	return false
}

// volume.AttachableVolumePlugin methods
var _ volume.AttachableVolumePlugin = &csiPlugin{}

var _ volume.DeviceMountableVolumePlugin = &csiPlugin{}

func (p *csiPlugin) NewAttacher() (volume.Attacher, error) {
	k8s := p.host.GetKubeClient()
	if k8s == nil {
		klog.Error(log("unable to get kubernetes client from host"))
		return nil, errors.New("unable to get Kubernetes client")
	}

	return &csiAttacher{
		plugin:        p,
		k8s:           k8s,
		waitSleepTime: 1 * time.Second,
	}, nil
}

func (p *csiPlugin) NewDeviceMounter() (volume.DeviceMounter, error) {
	return p.NewAttacher()
}

func (p *csiPlugin) NewDetacher() (volume.Detacher, error) {
	k8s := p.host.GetKubeClient()
	if k8s == nil {
		klog.Error(log("unable to get kubernetes client from host"))
		return nil, errors.New("unable to get Kubernetes client")
	}

	return &csiAttacher{
		plugin:        p,
		k8s:           k8s,
		waitSleepTime: 1 * time.Second,
	}, nil
}

func (p *csiPlugin) CanAttach(spec *volume.Spec) bool {
	if spec.PersistentVolume == nil {
		klog.Error(log("plugin.CanAttach test failed, spec missing PersistentVolume"))
		return false
	}

	var driverName string
	if spec.PersistentVolume.Spec.CSI != nil {
		driverName = spec.PersistentVolume.Spec.CSI.Driver
	} else {
		klog.Error(log("plugin.CanAttach test failed, spec missing CSIPersistentVolume"))
		return false
	}

	skipAttach, err := p.skipAttach(driverName)

	if err != nil {
		klog.Error(log("plugin.CanAttach error when calling plugin.skipAttach for driver %s: %s", driverName, err))
	}

	return !skipAttach
}

func (p *csiPlugin) NewDeviceUnmounter() (volume.DeviceUnmounter, error) {
	return p.NewDetacher()
}

func (p *csiPlugin) GetDeviceMountRefs(deviceMountPath string) ([]string, error) {
	m := p.host.GetMounter(p.GetPluginName())
	return m.GetMountRefs(deviceMountPath)
}

// BlockVolumePlugin methods
var _ volume.BlockVolumePlugin = &csiPlugin{}

func (p *csiPlugin) NewBlockVolumeMapper(spec *volume.Spec, podRef *api.Pod, opts volume.VolumeOptions) (volume.BlockVolumeMapper, error) {
	if !p.blockEnabled {
		return nil, errors.New("CSIBlockVolume feature not enabled")
	}

	pvSource, err := getCSISourceFromSpec(spec)
	if err != nil {
		return nil, err
	}
	readOnly, err := getReadOnlyFromSpec(spec)
	if err != nil {
		return nil, err
	}

	klog.V(4).Info(log("setting up block mapper for [volume=%v,driver=%v]", pvSource.VolumeHandle, pvSource.Driver))
	client, err := newCsiDriverClient(csiDriverName(pvSource.Driver))
	if err != nil {
		return nil, err
	}

	k8s := p.host.GetKubeClient()
	if k8s == nil {
		klog.Error(log("failed to get a kubernetes client"))
		return nil, errors.New("failed to get a Kubernetes client")
	}

	mapper := &csiBlockMapper{
		csiClient:  client,
		k8s:        k8s,
		plugin:     p,
		volumeID:   pvSource.VolumeHandle,
		driverName: csiDriverName(pvSource.Driver),
		readOnly:   readOnly,
		spec:       spec,
		specName:   spec.Name(),
		podUID:     podRef.UID,
	}

	// Save volume info in pod dir
	dataDir := getVolumeDeviceDataDir(spec.Name(), p.host)

	if err := os.MkdirAll(dataDir, 0750); err != nil {
		klog.Error(log("failed to create data dir %s:  %v", dataDir, err))
		return nil, err
	}
	klog.V(4).Info(log("created path successfully [%s]", dataDir))

	// persist volume info data for teardown
	node := string(p.host.GetNodeName())
	attachID := getAttachmentName(pvSource.VolumeHandle, pvSource.Driver, node)
	volData := map[string]string{
		volDataKey.specVolID:    spec.Name(),
		volDataKey.volHandle:    pvSource.VolumeHandle,
		volDataKey.driverName:   pvSource.Driver,
		volDataKey.nodeName:     node,
		volDataKey.attachmentID: attachID,
	}

	if err := saveVolumeData(dataDir, volDataFileName, volData); err != nil {
		klog.Error(log("failed to save volume info data: %v", err))
		if err := os.RemoveAll(dataDir); err != nil {
			klog.Error(log("failed to remove dir after error [%s]: %v", dataDir, err))
			return nil, err
		}
		return nil, err
	}

	return mapper, nil
}

func (p *csiPlugin) NewBlockVolumeUnmapper(volName string, podUID types.UID) (volume.BlockVolumeUnmapper, error) {
	if !p.blockEnabled {
		return nil, errors.New("CSIBlockVolume feature not enabled")
	}

	klog.V(4).Infof(log("setting up block unmapper for [Spec=%v, podUID=%v]", volName, podUID))
	unmapper := &csiBlockMapper{
		plugin:   p,
		podUID:   podUID,
		specName: volName,
	}

	// load volume info from file
	dataDir := getVolumeDeviceDataDir(unmapper.specName, p.host)
	data, err := loadVolumeData(dataDir, volDataFileName)
	if err != nil {
		klog.Error(log("unmapper failed to load volume data file [%s]: %v", dataDir, err))
		return nil, err
	}
	unmapper.driverName = csiDriverName(data[volDataKey.driverName])
	unmapper.volumeID = data[volDataKey.volHandle]
	unmapper.csiClient, err = newCsiDriverClient(unmapper.driverName)
	if err != nil {
		return nil, err
	}

	return unmapper, nil
}

func (p *csiPlugin) ConstructBlockVolumeSpec(podUID types.UID, specVolName, mapPath string) (*volume.Spec, error) {
	if !p.blockEnabled {
		return nil, errors.New("CSIBlockVolume feature not enabled")
	}

	klog.V(4).Infof("plugin.ConstructBlockVolumeSpec [podUID=%s, specVolName=%s, path=%s]", string(podUID), specVolName, mapPath)

	dataDir := getVolumeDeviceDataDir(specVolName, p.host)
	volData, err := loadVolumeData(dataDir, volDataFileName)
	if err != nil {
		klog.Error(log("plugin.ConstructBlockVolumeSpec failed loading volume data using [%s]: %v", mapPath, err))
		return nil, err
	}

	klog.V(4).Info(log("plugin.ConstructBlockVolumeSpec extracted [%#v]", volData))

	blockMode := api.PersistentVolumeBlock
	pv := &api.PersistentVolume{
		ObjectMeta: meta.ObjectMeta{
			Name: volData[volDataKey.specVolID],
		},
		Spec: api.PersistentVolumeSpec{
			PersistentVolumeSource: api.PersistentVolumeSource{
				CSI: &api.CSIPersistentVolumeSource{
					Driver:       volData[volDataKey.driverName],
					VolumeHandle: volData[volDataKey.volHandle],
				},
			},
			VolumeMode: &blockMode,
		},
	}

	return volume.NewSpecFromPersistentVolume(pv, false), nil
}

func (p *csiPlugin) skipAttach(driver string) (bool, error) {
	if !utilfeature.DefaultFeatureGate.Enabled(features.CSIDriverRegistry) {
		return false, nil
	}
	if p.csiDriverLister == nil {
		return false, errors.New("CSIDriver lister does not exist")
	}
	csiDriver, err := p.csiDriverLister.Get(driver)
	if err != nil {
		if apierrs.IsNotFound(err) {
			// Don't skip attach if CSIDriver does not exist
			return false, nil
		}
		return false, err
	}
	if csiDriver.Spec.AttachRequired != nil && *csiDriver.Spec.AttachRequired == false {
		return true, nil
	}
	return false, nil
}

func (p *csiPlugin) getPublishContext(client clientset.Interface, handle, driver, nodeName string) (map[string]string, error) {
	skip, err := p.skipAttach(driver)
	if err != nil {
		return nil, err
	}
	if skip {
		return nil, nil
	}

	attachID := getAttachmentName(handle, driver, nodeName)

	// search for attachment by VolumeAttachment.Spec.Source.PersistentVolumeName
	attachment, err := client.StorageV1().VolumeAttachments().Get(attachID, meta.GetOptions{})
	if err != nil {
		return nil, err // This err already has enough context ("VolumeAttachment xyz not found")
	}

	if attachment == nil {
		err = errors.New("no existing VolumeAttachment found")
		return nil, err
	}
	return attachment.Status.AttachmentMetadata, nil
}

func unregisterDriver(driverName string) error {
	csiDrivers.Delete(driverName)

	if err := nim.UninstallCSIDriver(driverName); err != nil {
		klog.Errorf("Error uninstalling CSI driver: %v", err)
		return err
	}

	return nil
}

// Return the highest supported version
func highestSupportedVersion(versions []string) (*utilversion.Version, error) {
	if len(versions) == 0 {
		return nil, fmt.Errorf("CSI driver reporting empty array for supported versions")
	}

	// Sort by lowest to highest version
	sort.Slice(versions, func(i, j int) bool {
		parsedVersionI, err := utilversion.ParseGeneric(versions[i])
		if err != nil {
			// Push bad values to the bottom
			return true
		}

		parsedVersionJ, err := utilversion.ParseGeneric(versions[j])
		if err != nil {
			// Push bad values to the bottom
			return false
		}

		return parsedVersionI.LessThan(parsedVersionJ)
	})

	for i := len(versions) - 1; i >= 0; i-- {
		highestSupportedVersion, err := utilversion.ParseGeneric(versions[i])
		if err != nil {
			return nil, err
		}

		if highestSupportedVersion.Major() <= 1 {
			return highestSupportedVersion, nil
		}
	}

	return nil, fmt.Errorf("None of the CSI versions reported by this driver are supported")
}

// Only drivers that implement CSI 0.x are allowed to use deprecated socket dir.
func isDeprecatedSocketDirAllowed(versions []string) bool {
	for _, version := range versions {
		if isV0Version(version) {
			return true
		}
	}

	return false
}

func isV0Version(version string) bool {
	parsedVersion, err := utilversion.ParseGeneric(version)
	if err != nil {
		return false
	}

	return parsedVersion.Major() == 0
}

func isV1Version(version string) bool {
	parsedVersion, err := utilversion.ParseGeneric(version)
	if err != nil {
		return false
	}

	return parsedVersion.Major() == 1
}