WIP: kata containers

pkg/volumepathhandler/volume_path_handler.go

@@ -0,0 +1,297 @@
+/*
+Copyright 2018 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 volumepathhandler
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"k8s.io/klog"
+	"k8s.io/kubernetes/pkg/util/mount"
+
+	"k8s.io/apimachinery/pkg/types"
+)
+
+const (
+	losetupPath           = "losetup"
+	statPath              = "stat"
+	ErrDeviceNotFound     = "device not found"
+	ErrDeviceNotSupported = "device not supported"
+)
+
+// BlockVolumePathHandler defines a set of operations for handling block volume-related operations
+type BlockVolumePathHandler interface {
+	// MapDevice creates a symbolic link to block device under specified map path
+	MapDevice(devicePath string, mapPath string, linkName string, bindMount bool) error
+	// UnmapDevice removes a symbolic link to block device under specified map path
+	UnmapDevice(mapPath string, linkName string, bindMount bool) error
+	// RemovePath removes a file or directory on specified map path
+	RemoveMapPath(mapPath string) error
+	// IsSymlinkExist retruns true if specified symbolic link exists
+	IsSymlinkExist(mapPath string) (bool, error)
+	// IsDeviceBindMountExist retruns true if specified bind mount exists
+	IsDeviceBindMountExist(mapPath string) (bool, error)
+	// GetDeviceBindMountRefs searches bind mounts under global map path
+	GetDeviceBindMountRefs(devPath string, mapPath string) ([]string, error)
+	// FindGlobalMapPathUUIDFromPod finds {pod uuid} symbolic link under globalMapPath
+	// corresponding to map path symlink, and then return global map path with pod uuid.
+	FindGlobalMapPathUUIDFromPod(pluginDir, mapPath string, podUID types.UID) (string, error)
+	// AttachFileDevice takes a path to a regular file and makes it available as an
+	// attached block device.
+	AttachFileDevice(path string) (string, error)
+	// DetachFileDevice takes a path to the attached block device and
+	// detach it from block device.
+	DetachFileDevice(path string) error
+	// GetLoopDevice returns the full path to the loop device associated with the given path.
+	GetLoopDevice(path string) (string, error)
+}
+
+// NewBlockVolumePathHandler returns a new instance of BlockVolumeHandler.
+func NewBlockVolumePathHandler() BlockVolumePathHandler {
+	var volumePathHandler VolumePathHandler
+	return volumePathHandler
+}
+
+// VolumePathHandler is path related operation handlers for block volume
+type VolumePathHandler struct {
+}
+
+// MapDevice creates a symbolic link to block device under specified map path
+func (v VolumePathHandler) MapDevice(devicePath string, mapPath string, linkName string, bindMount bool) error {
+	// Example of global map path:
+	//   globalMapPath/linkName: plugins/kubernetes.io/{PluginName}/{DefaultKubeletVolumeDevicesDirName}/{volumePluginDependentPath}/{podUid}
+	//   linkName: {podUid}
+	//
+	// Example of pod device map path:
+	//   podDeviceMapPath/linkName: pods/{podUid}/{DefaultKubeletVolumeDevicesDirName}/{escapeQualifiedPluginName}/{volumeName}
+	//   linkName: {volumeName}
+	if len(devicePath) == 0 {
+		return fmt.Errorf("failed to map device to map path. devicePath is empty")
+	}
+	if len(mapPath) == 0 {
+		return fmt.Errorf("failed to map device to map path. mapPath is empty")
+	}
+	if !filepath.IsAbs(mapPath) {
+		return fmt.Errorf("the map path should be absolute: map path: %s", mapPath)
+	}
+	klog.V(5).Infof("MapDevice: devicePath %s", devicePath)
+	klog.V(5).Infof("MapDevice: mapPath %s", mapPath)
+	klog.V(5).Infof("MapDevice: linkName %s", linkName)
+
+	// Check and create mapPath
+	_, err := os.Stat(mapPath)
+	if err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("cannot validate map path: %s: %v", mapPath, err)
+	}
+	if err = os.MkdirAll(mapPath, 0750); err != nil {
+		return fmt.Errorf("failed to mkdir %s: %v", mapPath, err)
+	}
+
+	if bindMount {
+		return mapBindMountDevice(v, devicePath, mapPath, linkName)
+	}
+	return mapSymlinkDevice(v, devicePath, mapPath, linkName)
+}
+
+func mapBindMountDevice(v VolumePathHandler, devicePath string, mapPath string, linkName string) error {
+	// Check bind mount exists
+	linkPath := filepath.Join(mapPath, string(linkName))
+
+	file, err := os.Stat(linkPath)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return fmt.Errorf("failed to stat file %s: %v", linkPath, err)
+		}
+
+		// Create file
+		newFile, err := os.OpenFile(linkPath, os.O_CREATE|os.O_RDWR, 0750)
+		if err != nil {
+			return fmt.Errorf("failed to open file %s: %v", linkPath, err)
+		}
+		if err := newFile.Close(); err != nil {
+			return fmt.Errorf("failed to close file %s: %v", linkPath, err)
+		}
+	} else {
+		// Check if device file
+		// TODO: Need to check if this device file is actually the expected bind mount
+		if file.Mode()&os.ModeDevice == os.ModeDevice {
+			klog.Warningf("Warning: Map skipped because bind mount already exist on the path: %v", linkPath)
+			return nil
+		}
+
+		klog.Warningf("Warning: file %s is already exist but not mounted, skip creating file", linkPath)
+	}
+
+	// Bind mount file
+	mounter := &mount.SafeFormatAndMount{Interface: mount.New(""), Exec: mount.NewOSExec()}
+	if err := mounter.Mount(devicePath, linkPath, "" /* fsType */, []string{"bind"}); err != nil {
+		return fmt.Errorf("failed to bind mount devicePath: %s to linkPath %s: %v", devicePath, linkPath, err)
+	}
+
+	return nil
+}
+
+func mapSymlinkDevice(v VolumePathHandler, devicePath string, mapPath string, linkName string) error {
+	// Remove old symbolic link(or file) then create new one.
+	// This should be done because current symbolic link is
+	// stale across node reboot.
+	linkPath := filepath.Join(mapPath, string(linkName))
+	if err := os.Remove(linkPath); err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("failed to remove file %s: %v", linkPath, err)
+	}
+	return os.Symlink(devicePath, linkPath)
+}
+
+// UnmapDevice removes a symbolic link associated to block device under specified map path
+func (v VolumePathHandler) UnmapDevice(mapPath string, linkName string, bindMount bool) error {
+	if len(mapPath) == 0 {
+		return fmt.Errorf("failed to unmap device from map path. mapPath is empty")
+	}
+	klog.V(5).Infof("UnmapDevice: mapPath %s", mapPath)
+	klog.V(5).Infof("UnmapDevice: linkName %s", linkName)
+
+	if bindMount {
+		return unmapBindMountDevice(v, mapPath, linkName)
+	}
+	return unmapSymlinkDevice(v, mapPath, linkName)
+}
+
+func unmapBindMountDevice(v VolumePathHandler, mapPath string, linkName string) error {
+	// Check bind mount exists
+	linkPath := filepath.Join(mapPath, string(linkName))
+	if isMountExist, checkErr := v.IsDeviceBindMountExist(linkPath); checkErr != nil {
+		return checkErr
+	} else if !isMountExist {
+		klog.Warningf("Warning: Unmap skipped because bind mount does not exist on the path: %v", linkPath)
+
+		// Check if linkPath still exists
+		if _, err := os.Stat(linkPath); err != nil {
+			if !os.IsNotExist(err) {
+				return fmt.Errorf("failed to check if path %s exists: %v", linkPath, err)
+			}
+			// linkPath has already been removed
+			return nil
+		}
+		// Remove file
+		if err := os.Remove(linkPath); err != nil && !os.IsNotExist(err) {
+			return fmt.Errorf("failed to remove file %s: %v", linkPath, err)
+		}
+		return nil
+	}
+
+	// Unmount file
+	mounter := &mount.SafeFormatAndMount{Interface: mount.New(""), Exec: mount.NewOSExec()}
+	if err := mounter.Unmount(linkPath); err != nil {
+		return fmt.Errorf("failed to unmount linkPath %s: %v", linkPath, err)
+	}
+
+	// Remove file
+	if err := os.Remove(linkPath); err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("failed to remove file %s: %v", linkPath, err)
+	}
+
+	return nil
+}
+
+func unmapSymlinkDevice(v VolumePathHandler, mapPath string, linkName string) error {
+	// Check symbolic link exists
+	linkPath := filepath.Join(mapPath, string(linkName))
+	if islinkExist, checkErr := v.IsSymlinkExist(linkPath); checkErr != nil {
+		return checkErr
+	} else if !islinkExist {
+		klog.Warningf("Warning: Unmap skipped because symlink does not exist on the path: %v", linkPath)
+		return nil
+	}
+	return os.Remove(linkPath)
+}
+
+// RemoveMapPath removes a file or directory on specified map path
+func (v VolumePathHandler) RemoveMapPath(mapPath string) error {
+	if len(mapPath) == 0 {
+		return fmt.Errorf("failed to remove map path. mapPath is empty")
+	}
+	klog.V(5).Infof("RemoveMapPath: mapPath %s", mapPath)
+	err := os.RemoveAll(mapPath)
+	if err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("failed to remove directory %s: %v", mapPath, err)
+	}
+	return nil
+}
+
+// IsSymlinkExist returns true if specified file exists and the type is symbolik link.
+// If file doesn't exist, or file exists but not symbolic link, return false with no error.
+// On other cases, return false with error from Lstat().
+func (v VolumePathHandler) IsSymlinkExist(mapPath string) (bool, error) {
+	fi, err := os.Lstat(mapPath)
+	if err != nil {
+		// If file doesn't exist, return false and no error
+		if os.IsNotExist(err) {
+			return false, nil
+		}
+		// Return error from Lstat()
+		return false, fmt.Errorf("failed to Lstat file %s: %v", mapPath, err)
+	}
+	// If file exits and it's symbolic link, return true and no error
+	if fi.Mode()&os.ModeSymlink == os.ModeSymlink {
+		return true, nil
+	}
+	// If file exits but it's not symbolic link, return fale and no error
+	return false, nil
+}
+
+// IsDeviceBindMountExist returns true if specified file exists and the type is device.
+// If file doesn't exist, or file exists but not device, return false with no error.
+// On other cases, return false with error from Lstat().
+func (v VolumePathHandler) IsDeviceBindMountExist(mapPath string) (bool, error) {
+	fi, err := os.Lstat(mapPath)
+	if err != nil {
+		// If file doesn't exist, return false and no error
+		if os.IsNotExist(err) {
+			return false, nil
+		}
+
+		// Return error from Lstat()
+		return false, fmt.Errorf("failed to Lstat file %s: %v", mapPath, err)
+	}
+	// If file exits and it's device, return true and no error
+	if fi.Mode()&os.ModeDevice == os.ModeDevice {
+		return true, nil
+	}
+	// If file exits but it's not device, return fale and no error
+	return false, nil
+}
+
+// GetDeviceBindMountRefs searches bind mounts under global map path
+func (v VolumePathHandler) GetDeviceBindMountRefs(devPath string, mapPath string) ([]string, error) {
+	var refs []string
+	files, err := ioutil.ReadDir(mapPath)
+	if err != nil {
+		return nil, fmt.Errorf("directory cannot read %v", err)
+	}
+	for _, file := range files {
+		if file.Mode()&os.ModeDevice != os.ModeDevice {
+			continue
+		}
+		filename := file.Name()
+		// TODO: Might need to check if the file is actually linked to devPath
+		refs = append(refs, filepath.Join(mapPath, filename))
+	}
+	klog.V(5).Infof("GetDeviceBindMountRefs: refs %v", refs)
+	return refs, nil
+}