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moby--moby/daemon/volumes_unix.go
David Calavera 55a601e3f1 Vendor libcontainer v0.0.4
Noteworthy changes:

- Add Prestart/Poststop hook support
- Fix bug finding cgroup mount directory
- Add OomScoreAdj as a container configuration option
- Ensure the cleanup jobs in the deferrer are executed on error
- Don't make modifications to /dev when it is bind mounted

Other changes in runc:

https://github.com/opencontainers/runc/compare/v0.0.3...v0.0.4

Signed-off-by: David Calavera <david.calavera@gmail.com>
2015-09-11 16:17:59 -04:00

414 lines
12 KiB
Go

// +build !windows
package daemon
import (
"fmt"
"io/ioutil"
"os"
"path/filepath"
"sort"
"strings"
"github.com/Sirupsen/logrus"
"github.com/docker/docker/daemon/execdriver"
"github.com/docker/docker/pkg/system"
"github.com/docker/docker/runconfig"
"github.com/docker/docker/volume"
volumedrivers "github.com/docker/docker/volume/drivers"
"github.com/docker/docker/volume/local"
"github.com/opencontainers/runc/libcontainer/label"
)
// copyOwnership copies the permissions and uid:gid of the source file
// to the destination file
func copyOwnership(source, destination string) error {
stat, err := system.Stat(source)
if err != nil {
return err
}
if err := os.Chown(destination, int(stat.UID()), int(stat.Gid())); err != nil {
return err
}
return os.Chmod(destination, os.FileMode(stat.Mode()))
}
// setupMounts iterates through each of the mount points for a container and
// calls Setup() on each. It also looks to see if is a network mount such as
// /etc/resolv.conf, and if it is not, appends it to the array of mounts.
func (container *Container) setupMounts() ([]execdriver.Mount, error) {
var mounts []execdriver.Mount
for _, m := range container.MountPoints {
path, err := m.Setup()
if err != nil {
return nil, err
}
if !container.trySetNetworkMount(m.Destination, path) {
mounts = append(mounts, execdriver.Mount{
Source: path,
Destination: m.Destination,
Writable: m.RW,
})
}
}
mounts = sortMounts(mounts)
return append(mounts, container.networkMounts()...), nil
}
// parseBindMount validates the configuration of mount information in runconfig is valid.
func parseBindMount(spec, volumeDriver string) (*mountPoint, error) {
bind := &mountPoint{
RW: true,
}
arr := strings.Split(spec, ":")
switch len(arr) {
case 2:
bind.Destination = arr[1]
case 3:
bind.Destination = arr[1]
mode := arr[2]
if !volume.ValidMountMode(mode) {
return nil, fmt.Errorf("invalid mode for volumes-from: %s", mode)
}
bind.RW = volume.ReadWrite(mode)
// Mode field is used by SELinux to decide whether to apply label
bind.Mode = mode
default:
return nil, fmt.Errorf("Invalid volume specification: %s", spec)
}
//validate the volumes destination path
if !filepath.IsAbs(bind.Destination) {
return nil, fmt.Errorf("Invalid volume destination path: %s mount path must be absolute.", bind.Destination)
}
name, source, err := parseVolumeSource(arr[0])
if err != nil {
return nil, err
}
if len(source) == 0 {
bind.Driver = volumeDriver
if len(bind.Driver) == 0 {
bind.Driver = volume.DefaultDriverName
}
} else {
bind.Source = filepath.Clean(source)
}
bind.Name = name
bind.Destination = filepath.Clean(bind.Destination)
return bind, nil
}
// sortMounts sorts an array of mounts in lexicographic order. This ensure that
// when mounting, the mounts don't shadow other mounts. For example, if mounting
// /etc and /etc/resolv.conf, /etc/resolv.conf must not be mounted first.
func sortMounts(m []execdriver.Mount) []execdriver.Mount {
sort.Sort(mounts(m))
return m
}
type mounts []execdriver.Mount
// Len returns the number of mounts
func (m mounts) Len() int {
return len(m)
}
// Less returns true if the number of parts (a/b/c would be 3 parts) in the
// mount indexed by parameter 1 is less than that of the mount indexed by
// parameter 2.
func (m mounts) Less(i, j int) bool {
return m.parts(i) < m.parts(j)
}
// Swap swaps two items in an array of mounts.
func (m mounts) Swap(i, j int) {
m[i], m[j] = m[j], m[i]
}
// parts returns the number of parts in the destination of a mount.
func (m mounts) parts(i int) int {
return len(strings.Split(filepath.Clean(m[i].Destination), string(os.PathSeparator)))
}
// migrateVolume links the contents of a volume created pre Docker 1.7
// into the location expected by the local driver.
// It creates a symlink from DOCKER_ROOT/vfs/dir/VOLUME_ID to DOCKER_ROOT/volumes/VOLUME_ID/_container_data.
// It preserves the volume json configuration generated pre Docker 1.7 to be able to
// downgrade from Docker 1.7 to Docker 1.6 without losing volume compatibility.
func migrateVolume(id, vfs string) error {
l, err := volumedrivers.Lookup(volume.DefaultDriverName)
if err != nil {
return err
}
newDataPath := l.(*local.Root).DataPath(id)
fi, err := os.Stat(newDataPath)
if err != nil && !os.IsNotExist(err) {
return err
}
if fi != nil && fi.IsDir() {
return nil
}
return os.Symlink(vfs, newDataPath)
}
// validVolumeLayout checks whether the volume directory layout
// is valid to work with Docker post 1.7 or not.
func validVolumeLayout(files []os.FileInfo) bool {
if len(files) == 1 && files[0].Name() == local.VolumeDataPathName && files[0].IsDir() {
return true
}
if len(files) != 2 {
return false
}
for _, f := range files {
if f.Name() == "config.json" ||
(f.Name() == local.VolumeDataPathName && f.Mode()&os.ModeSymlink == os.ModeSymlink) {
// Old volume configuration, we ignore it
continue
}
return false
}
return true
}
// verifyVolumesInfo ports volumes configured for the containers pre docker 1.7.
// It reads the container configuration and creates valid mount points for the old volumes.
func (daemon *Daemon) verifyVolumesInfo(container *Container) error {
// Inspect old structures only when we're upgrading from old versions
// to versions >= 1.7 and the MountPoints has not been populated with volumes data.
if len(container.MountPoints) == 0 && len(container.Volumes) > 0 {
for destination, hostPath := range container.Volumes {
vfsPath := filepath.Join(daemon.root, "vfs", "dir")
rw := container.VolumesRW != nil && container.VolumesRW[destination]
if strings.HasPrefix(hostPath, vfsPath) {
id := filepath.Base(hostPath)
if err := migrateVolume(id, hostPath); err != nil {
return err
}
container.addLocalMountPoint(id, destination, rw)
} else { // Bind mount
id, source, err := parseVolumeSource(hostPath)
// We should not find an error here coming
// from the old configuration, but who knows.
if err != nil {
return err
}
container.addBindMountPoint(id, source, destination, rw)
}
}
} else if len(container.MountPoints) > 0 {
// Volumes created with a Docker version >= 1.7. We verify integrity in case of data created
// with Docker 1.7 RC versions that put the information in
// DOCKER_ROOT/volumes/VOLUME_ID rather than DOCKER_ROOT/volumes/VOLUME_ID/_container_data.
l, err := volumedrivers.Lookup(volume.DefaultDriverName)
if err != nil {
return err
}
for _, m := range container.MountPoints {
if m.Driver != volume.DefaultDriverName {
continue
}
dataPath := l.(*local.Root).DataPath(m.Name)
volumePath := filepath.Dir(dataPath)
d, err := ioutil.ReadDir(volumePath)
if err != nil {
// If the volume directory doesn't exist yet it will be recreated,
// so we only return the error when there is a different issue.
if !os.IsNotExist(err) {
return err
}
// Do not check when the volume directory does not exist.
continue
}
if validVolumeLayout(d) {
continue
}
if err := os.Mkdir(dataPath, 0755); err != nil {
return err
}
// Move data inside the data directory
for _, f := range d {
oldp := filepath.Join(volumePath, f.Name())
newp := filepath.Join(dataPath, f.Name())
if err := os.Rename(oldp, newp); err != nil {
logrus.Errorf("Unable to move %s to %s\n", oldp, newp)
}
}
}
return container.toDiskLocking()
}
return nil
}
// parseVolumesFrom ensure that the supplied volumes-from is valid.
func parseVolumesFrom(spec string) (string, string, error) {
if len(spec) == 0 {
return "", "", fmt.Errorf("malformed volumes-from specification: %s", spec)
}
specParts := strings.SplitN(spec, ":", 2)
id := specParts[0]
mode := "rw"
if len(specParts) == 2 {
mode = specParts[1]
if !volume.ValidMountMode(mode) {
return "", "", fmt.Errorf("invalid mode for volumes-from: %s", mode)
}
}
return id, mode, nil
}
// registerMountPoints initializes the container mount points with the configured volumes and bind mounts.
// It follows the next sequence to decide what to mount in each final destination:
//
// 1. Select the previously configured mount points for the containers, if any.
// 2. Select the volumes mounted from another containers. Overrides previously configured mount point destination.
// 3. Select the bind mounts set by the client. Overrides previously configured mount point destinations.
func (daemon *Daemon) registerMountPoints(container *Container, hostConfig *runconfig.HostConfig) error {
binds := map[string]bool{}
mountPoints := map[string]*mountPoint{}
// 1. Read already configured mount points.
for name, point := range container.MountPoints {
mountPoints[name] = point
}
// 2. Read volumes from other containers.
for _, v := range hostConfig.VolumesFrom {
containerID, mode, err := parseVolumesFrom(v)
if err != nil {
return err
}
c, err := daemon.Get(containerID)
if err != nil {
return err
}
for _, m := range c.MountPoints {
cp := &mountPoint{
Name: m.Name,
Source: m.Source,
RW: m.RW && volume.ReadWrite(mode),
Driver: m.Driver,
Destination: m.Destination,
}
if len(cp.Source) == 0 {
v, err := daemon.createVolume(cp.Name, cp.Driver, nil)
if err != nil {
return err
}
cp.Volume = v
}
mountPoints[cp.Destination] = cp
}
}
// 3. Read bind mounts
for _, b := range hostConfig.Binds {
// #10618
bind, err := parseBindMount(b, hostConfig.VolumeDriver)
if err != nil {
return err
}
if binds[bind.Destination] {
return fmt.Errorf("Duplicate bind mount %s", bind.Destination)
}
if len(bind.Name) > 0 && len(bind.Driver) > 0 {
// create the volume
v, err := daemon.createVolume(bind.Name, bind.Driver, nil)
if err != nil {
return err
}
bind.Volume = v
bind.Source = v.Path()
// bind.Name is an already existing volume, we need to use that here
bind.Driver = v.DriverName()
// Since this is just a named volume and not a typical bind, set to shared mode `z`
if bind.Mode == "" {
bind.Mode = "z"
}
}
shared := label.IsShared(bind.Mode)
if err := label.Relabel(bind.Source, container.MountLabel, shared); err != nil {
return err
}
binds[bind.Destination] = true
mountPoints[bind.Destination] = bind
}
// Keep backwards compatible structures
bcVolumes := map[string]string{}
bcVolumesRW := map[string]bool{}
for _, m := range mountPoints {
if m.BackwardsCompatible() {
bcVolumes[m.Destination] = m.Path()
bcVolumesRW[m.Destination] = m.RW
// This mountpoint is replacing an existing one, so the count needs to be decremented
if mp, exists := container.MountPoints[m.Destination]; exists && mp.Volume != nil {
daemon.volumes.Decrement(mp.Volume)
}
}
}
container.Lock()
container.MountPoints = mountPoints
container.Volumes = bcVolumes
container.VolumesRW = bcVolumesRW
container.Unlock()
return nil
}
// createVolume creates a volume.
func (daemon *Daemon) createVolume(name, driverName string, opts map[string]string) (volume.Volume, error) {
v, err := daemon.volumes.Create(name, driverName, opts)
if err != nil {
return nil, err
}
daemon.volumes.Increment(v)
return v, nil
}
// parseVolumeSource parses the origin sources that's mounted into the container.
func parseVolumeSource(spec string) (string, string, error) {
if !filepath.IsAbs(spec) {
return spec, "", nil
}
return "", spec, nil
}
// BackwardsCompatible decides whether this mount point can be
// used in old versions of Docker or not.
// Only bind mounts and local volumes can be used in old versions of Docker.
func (m *mountPoint) BackwardsCompatible() bool {
return len(m.Source) > 0 || m.Driver == volume.DefaultDriverName
}