Extract volumepathhandler into seperate directory

pkg/volume/util/volumepathhandler/volume_path_handler.go

+/*
+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"
+	"path/filepath"
+
+	"github.com/golang/glog"
+
+	"k8s.io/apimachinery/pkg/types"
+)
+
+const (
+	losetupPath           = "losetup"
+	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) error
+	// UnmapDevice removes a symbolic link to block device under specified map path
+	UnmapDevice(mapPath string, linkName string) 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)
+	// GetDeviceSymlinkRefs searches symbolic links under global map path
+	GetDeviceSymlinkRefs(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)
+	// GetLoopDevice returns the full path to the loop device associated with the given path.
+	GetLoopDevice(path string) (string, error)
+	// RemoveLoopDevice removes specified loopback device
+	RemoveLoopDevice(device 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) 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)
+	}
+	glog.V(5).Infof("MapDevice: devicePath %s", devicePath)
+	glog.V(5).Infof("MapDevice: mapPath %s", mapPath)
+	glog.V(5).Infof("MapDevice: linkName %s", linkName)
+
+	// Check and create mapPath
+	_, err := os.Stat(mapPath)
+	if err != nil && !os.IsNotExist(err) {
+		glog.Errorf("cannot validate map path: %s", mapPath)
+		return err
+	}
+	if err = os.MkdirAll(mapPath, 0750); err != nil {
+		return fmt.Errorf("Failed to mkdir %s, error %v", mapPath, err)
+	}
+	// Remove old symbolic link(or file) then create new one.
+	// This should be done because current symbolic link is
+	// stale accross node reboot.
+	linkPath := path.Join(mapPath, string(linkName))
+	if err = os.Remove(linkPath); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	err = os.Symlink(devicePath, linkPath)
+	return err
+}
+
+// UnmapDevice removes a symbolic link associated to block device under specified map path
+func (v VolumePathHandler) UnmapDevice(mapPath string, linkName string) error {
+	if len(mapPath) == 0 {
+		return fmt.Errorf("Failed to unmap device from map path. mapPath is empty")
+	}
+	glog.V(5).Infof("UnmapDevice: mapPath %s", mapPath)
+	glog.V(5).Infof("UnmapDevice: linkName %s", linkName)
+
+	// Check symbolic link exists
+	linkPath := path.Join(mapPath, string(linkName))
+	if islinkExist, checkErr := v.IsSymlinkExist(linkPath); checkErr != nil {
+		return checkErr
+	} else if !islinkExist {
+		glog.Warningf("Warning: Unmap skipped because symlink does not exist on the path: %v", linkPath)
+		return nil
+	}
+	err := os.Remove(linkPath)
+	return err
+}
+
+// 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")
+	}
+	glog.V(5).Infof("RemoveMapPath: mapPath %s", mapPath)
+	err := os.RemoveAll(mapPath)
+	if err != nil && !os.IsNotExist(err) {
+		return 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 symbolick 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 exits and it's symbolick link, return true and no error
+		if fi.Mode()&os.ModeSymlink == os.ModeSymlink {
+			return true, nil
+		}
+		// If file exits but it's not symbolick link, return fale and no error
+		return false, nil
+	}
+	// If file doesn't exist, return false and no error
+	if os.IsNotExist(err) {
+		return false, nil
+	}
+	// Return error from Lstat()
+	return false, err
+}
+
+// GetDeviceSymlinkRefs searches symbolic links under global map path
+func (v VolumePathHandler) GetDeviceSymlinkRefs(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.ModeSymlink != os.ModeSymlink {
+			continue
+		}
+		filename := file.Name()
+		filepath, err := os.Readlink(path.Join(mapPath, filename))
+		if err != nil {
+			return nil, fmt.Errorf("Symbolic link cannot be retrieved %v", err)
+		}
+		glog.V(5).Infof("GetDeviceSymlinkRefs: filepath: %v, devPath: %v", filepath, devPath)
+		if filepath == devPath {
+			refs = append(refs, path.Join(mapPath, filename))
+		}
+	}
+	glog.V(5).Infof("GetDeviceSymlinkRefs: refs %v", refs)
+	return refs, nil
+}
+
+// FindGlobalMapPathUUIDFromPod finds {pod uuid} symbolic link under globalMapPath
+// corresponding to map path symlink, and then return global map path with pod uuid.
+// ex. mapPath symlink: pods/{podUid}}/{DefaultKubeletVolumeDevicesDirName}/{escapeQualifiedPluginName}/{volumeName} -> /dev/sdX
+//     globalMapPath/{pod uuid}: plugins/kubernetes.io/{PluginName}/{DefaultKubeletVolumeDevicesDirName}/{volumePluginDependentPath}/{pod uuid} -> /dev/sdX
+func (v VolumePathHandler) FindGlobalMapPathUUIDFromPod(pluginDir, mapPath string, podUID types.UID) (string, error) {
+	var globalMapPathUUID string
+	// Find symbolic link named pod uuid under plugin dir
+	err := filepath.Walk(pluginDir, func(path string, fi os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if (fi.Mode()&os.ModeSymlink == os.ModeSymlink) && (fi.Name() == string(podUID)) {
+			glog.V(5).Infof("FindGlobalMapPathFromPod: path %s, mapPath %s", path, mapPath)
+			if res, err := compareSymlinks(path, mapPath); err == nil && res {
+				globalMapPathUUID = path
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		return "", err
+	}
+	glog.V(5).Infof("FindGlobalMapPathFromPod: globalMapPathUUID %s", globalMapPathUUID)
+	// Return path contains global map path + {pod uuid}
+	return globalMapPathUUID, nil
+}
+
+func compareSymlinks(global, pod string) (bool, error) {
+	devGlobal, err := os.Readlink(global)
+	if err != nil {
+		return false, err
+	}
+	devPod, err := os.Readlink(pod)
+	if err != nil {
+		return false, err
+	}
+	glog.V(5).Infof("CompareSymlinks: devGloBal %s, devPod %s", devGlobal, devPod)
+	if devGlobal == devPod {
+		return true, nil
+	}
+	return false, nil
+}

pkg/volume/util/volumepathhandler/volume_path_handler_linux.go

+// +build linux
+
+/*
+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 (
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/golang/glog"
+)
+
+// AttachFileDevice takes a path to a regular file and makes it available as an
+// attached block device.
+func (v VolumePathHandler) AttachFileDevice(path string) (string, error) {
+	blockDevicePath, err := v.GetLoopDevice(path)
+	if err != nil && err.Error() != ErrDeviceNotFound {
+		return "", err
+	}
+
+	// If no existing loop device for the path, create one
+	if blockDevicePath == "" {
+		glog.V(4).Infof("Creating device for path: %s", path)
+		blockDevicePath, err = makeLoopDevice(path)
+		if err != nil {
+			return "", err
+		}
+	}
+	return blockDevicePath, nil
+}
+
+// GetLoopDevice returns the full path to the loop device associated with the given path.
+func (v VolumePathHandler) GetLoopDevice(path string) (string, error) {
+	_, err := os.Stat(path)
+	if os.IsNotExist(err) {
+		return "", errors.New(ErrDeviceNotFound)
+	}
+	if err != nil {
+		return "", fmt.Errorf("not attachable: %v", err)
+	}
+
+	args := []string{"-j", path}
+	cmd := exec.Command(losetupPath, args...)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		glog.V(2).Infof("Failed device discover command for path %s: %v", path, err)
+		return "", err
+	}
+	return parseLosetupOutputForDevice(out)
+}
+
+func makeLoopDevice(path string) (string, error) {
+	args := []string{"-f", "--show", path}
+	cmd := exec.Command(losetupPath, args...)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		glog.V(2).Infof("Failed device create command for path %s: %v", path, err)
+		return "", err
+	}
+	return parseLosetupOutputForDevice(out)
+}
+
+// RemoveLoopDevice removes specified loopback device
+func (v VolumePathHandler) RemoveLoopDevice(device string) error {
+	args := []string{"-d", device}
+	cmd := exec.Command(losetupPath, args...)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		if _, err := os.Stat(device); os.IsNotExist(err) {
+			return nil
+		}
+		glog.V(2).Infof("Failed to remove loopback device: %s: %v %s", device, err, out)
+		return err
+	}
+	return nil
+}
+
+func parseLosetupOutputForDevice(output []byte) (string, error) {
+	if len(output) == 0 {
+		return "", errors.New(ErrDeviceNotFound)
+	}
+
+	// losetup returns device in the format:
+	// /dev/loop1: [0073]:148662 (/dev/sda)
+	device := strings.TrimSpace(strings.SplitN(string(output), ":", 2)[0])
+	if len(device) == 0 {
+		return "", errors.New(ErrDeviceNotFound)
+	}
+	return device, nil
+}

pkg/volume/util/volumepathhandler/volume_path_handler_unsupported.go

+// +build !linux
+
+/*
+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"
+)
+
+// AttachFileDevice takes a path to a regular file and makes it available as an
+// attached block device.
+func (v VolumePathHandler) AttachFileDevice(path string) (string, error) {
+	return "", fmt.Errorf("AttachFileDevice not supported for this build.")
+}
+
+// GetLoopDevice returns the full path to the loop device associated with the given path.
+func (v VolumePathHandler) GetLoopDevice(path string) (string, error) {
+	return "", fmt.Errorf("GetLoopDevice not supported for this build.")
+}
+
+// RemoveLoopDevice removes specified loopback device
+func (v VolumePathHandler) RemoveLoopDevice(device string) error {
+	return fmt.Errorf("RemoveLoopDevice not supported for this build.")
+}