Switch to github.com/golang/dep for vendoring

Signed-off-by: Mrunal Patel <mrunalp@gmail.com>

vendor/k8s.io/kubernetes/pkg/util/mount/nsenter_mount.go

@@ -0,0 +1,231 @@
+// +build linux
+
+/*
+Copyright 2014 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 mount
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/golang/glog"
+	"k8s.io/kubernetes/pkg/util/exec"
+)
+
+// NsenterMounter is part of experimental support for running the kubelet
+// in a container.  Currently, all docker containers receive their own mount
+// namespaces.  NsenterMounter works by executing nsenter to run commands in
+// the host's mount namespace.
+//
+// NsenterMounter requires:
+//
+// 1.  Docker >= 1.6 due to the dependency on the slave propagation mode
+//     of the bind-mount of the kubelet root directory in the container.
+//     Docker 1.5 used a private propagation mode for bind-mounts, so mounts
+//     performed in the host's mount namespace do not propagate out to the
+//     bind-mount in this docker version.
+// 2.  The host's root filesystem must be available at /rootfs
+// 3.  The nsenter binary must be on the Kubelet process' PATH in the container's
+//     filesystem.
+// 4.  The Kubelet process must have CAP_SYS_ADMIN (required by nsenter); at
+//     the present, this effectively means that the kubelet is running in a
+//     privileged container.
+// 5.  The volume path used by the Kubelet must be the same inside and outside
+//     the container and be writable by the container (to initialize volume)
+//     contents. TODO: remove this requirement.
+// 6.  The host image must have mount, findmnt, and umount binaries in /bin,
+//     /usr/sbin, or /usr/bin
+//
+// For more information about mount propagation modes, see:
+//   https://www.kernel.org/doc/Documentation/filesystems/sharedsubtree.txt
+type NsenterMounter struct {
+	// a map of commands to their paths on the host filesystem
+	paths map[string]string
+}
+
+func NewNsenterMounter() *NsenterMounter {
+	m := &NsenterMounter{
+		paths: map[string]string{
+			"mount":   "",
+			"findmnt": "",
+			"umount":  "",
+		},
+	}
+	// search for the mount command in other locations besides /usr/bin
+	for binary := range m.paths {
+		// default to root
+		m.paths[binary] = filepath.Join("/", binary)
+		for _, path := range []string{"/bin", "/usr/sbin", "/usr/bin"} {
+			binPath := filepath.Join(path, binary)
+			if _, err := os.Stat(filepath.Join(hostRootFsPath, binPath)); err != nil {
+				continue
+			}
+			m.paths[binary] = binPath
+			break
+		}
+		// TODO: error, so that the kubelet can stop if the mounts don't exist
+	}
+	return m
+}
+
+// NsenterMounter implements mount.Interface
+var _ = Interface(&NsenterMounter{})
+
+const (
+	hostRootFsPath     = "/rootfs"
+	hostProcMountsPath = "/rootfs/proc/1/mounts"
+	nsenterPath        = "nsenter"
+)
+
+// Mount runs mount(8) in the host's root mount namespace.  Aside from this
+// aspect, Mount has the same semantics as the mounter returned by mount.New()
+func (n *NsenterMounter) Mount(source string, target string, fstype string, options []string) error {
+	bind, bindRemountOpts := isBind(options)
+
+	if bind {
+		err := n.doNsenterMount(source, target, fstype, []string{"bind"})
+		if err != nil {
+			return err
+		}
+		return n.doNsenterMount(source, target, fstype, bindRemountOpts)
+	}
+
+	return n.doNsenterMount(source, target, fstype, options)
+}
+
+// doNsenterMount nsenters the host's mount namespace and performs the
+// requested mount.
+func (n *NsenterMounter) doNsenterMount(source, target, fstype string, options []string) error {
+	glog.V(5).Infof("nsenter Mounting %s %s %s %v", source, target, fstype, options)
+	args := n.makeNsenterArgs(source, target, fstype, options)
+
+	glog.V(5).Infof("Mount command: %v %v", nsenterPath, args)
+	exec := exec.New()
+	outputBytes, err := exec.Command(nsenterPath, args...).CombinedOutput()
+	if len(outputBytes) != 0 {
+		glog.V(5).Infof("Output of mounting %s to %s: %v", source, target, string(outputBytes))
+	}
+
+	return err
+}
+
+// makeNsenterArgs makes a list of argument to nsenter in order to do the
+// requested mount.
+func (n *NsenterMounter) makeNsenterArgs(source, target, fstype string, options []string) []string {
+	nsenterArgs := []string{
+		"--mount=/rootfs/proc/1/ns/mnt",
+		"--",
+		n.absHostPath("mount"),
+	}
+
+	args := makeMountArgs(source, target, fstype, options)
+
+	return append(nsenterArgs, args...)
+}
+
+// Unmount runs umount(8) in the host's mount namespace.
+func (n *NsenterMounter) Unmount(target string) error {
+	args := []string{
+		"--mount=/rootfs/proc/1/ns/mnt",
+		"--",
+		n.absHostPath("umount"),
+		target,
+	}
+
+	glog.V(5).Infof("Unmount command: %v %v", nsenterPath, args)
+	exec := exec.New()
+	outputBytes, err := exec.Command(nsenterPath, args...).CombinedOutput()
+	if len(outputBytes) != 0 {
+		glog.V(5).Infof("Output of unmounting %s: %v", target, string(outputBytes))
+	}
+
+	return err
+}
+
+// List returns a list of all mounted filesystems in the host's mount namespace.
+func (*NsenterMounter) List() ([]MountPoint, error) {
+	return listProcMounts(hostProcMountsPath)
+}
+
+// IsLikelyNotMountPoint determines whether a path is a mountpoint by calling findmnt
+// in the host's root mount namespace.
+func (n *NsenterMounter) IsLikelyNotMountPoint(file string) (bool, error) {
+	file, err := filepath.Abs(file)
+	if err != nil {
+		return true, err
+	}
+
+	// Check the directory exists
+	if _, err = os.Stat(file); os.IsNotExist(err) {
+		glog.V(5).Infof("findmnt: directory %s does not exist", file)
+		return true, err
+	}
+	// Add --first-only option: since we are testing for the absence of a mountpoint, it is sufficient to get only
+	// the first of multiple possible mountpoints using --first-only.
+	// Also add fstype output to make sure that the output of target file will give the full path
+	// TODO: Need more refactoring for this function. Track the solution with issue #26996
+	args := []string{"--mount=/rootfs/proc/1/ns/mnt", "--", n.absHostPath("findmnt"), "-o", "target,fstype", "--noheadings", "--first-only", "--target", file}
+	glog.V(5).Infof("findmnt command: %v %v", nsenterPath, args)
+
+	exec := exec.New()
+	out, err := exec.Command(nsenterPath, args...).CombinedOutput()
+	if err != nil {
+		glog.V(2).Infof("Failed findmnt command for path %s: %v", file, err)
+		// Different operating systems behave differently for paths which are not mount points.
+		// On older versions (e.g. 2.20.1) we'd get error, on newer ones (e.g. 2.26.2) we'd get "/".
+		// It's safer to assume that it's not a mount point.
+		return true, nil
+	}
+	mountTarget := strings.Split(string(out), " ")[0]
+	mountTarget = strings.TrimSuffix(mountTarget, "\n")
+	glog.V(5).Infof("IsLikelyNotMountPoint findmnt output for path %s: %v:", file, mountTarget)
+
+	if mountTarget == file {
+		glog.V(5).Infof("IsLikelyNotMountPoint: %s is a mount point", file)
+		return false, nil
+	}
+	glog.V(5).Infof("IsLikelyNotMountPoint: %s is not a mount point", file)
+	return true, nil
+}
+
+// DeviceOpened checks if block device in use by calling Open with O_EXCL flag.
+// Returns true if open returns errno EBUSY, and false if errno is nil.
+// Returns an error if errno is any error other than EBUSY.
+// Returns with error if pathname is not a device.
+func (n *NsenterMounter) DeviceOpened(pathname string) (bool, error) {
+	return exclusiveOpenFailsOnDevice(pathname)
+}
+
+// PathIsDevice uses FileInfo returned from os.Stat to check if path refers
+// to a device.
+func (n *NsenterMounter) PathIsDevice(pathname string) (bool, error) {
+	return pathIsDevice(pathname)
+}
+
+//GetDeviceNameFromMount given a mount point, find the volume id from checking /proc/mounts
+func (n *NsenterMounter) GetDeviceNameFromMount(mountPath, pluginDir string) (string, error) {
+	return getDeviceNameFromMount(n, mountPath, pluginDir)
+}
+
+func (n *NsenterMounter) absHostPath(command string) string {
+	path, ok := n.paths[command]
+	if !ok {
+		return command
+	}
+	return path
+}