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moby--moby/volume/local/local.go
Brian Goff d3eca4451d Move responsibility of ls/inspect to volume driver
Makes `docker volume ls` and `docker volume inspect` ask the volume
drivers rather than only using what is cached locally.

Previously in order to use a volume from an external driver, one would
either have to use `docker volume create` or have a container that is
already using that volume for it to be visible to the other volume
API's.

For keeping uniqueness of volume names in the daemon, names are bound to
a driver on a first come first serve basis. If two drivers have a volume
with the same name, the first one is chosen, and a warning is logged
about the second one.

Adds 2 new methods to the plugin API, `List` and `Get`.
If a plugin does not implement these endpoints, a user will not be able
to find the specified volumes as well requests go through the drivers.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2016-01-05 16:28:38 -05:00

232 lines
5.8 KiB
Go

// Package local provides the default implementation for volumes. It
// is used to mount data volume containers and directories local to
// the host server.
package local
import (
"errors"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"sync"
derr "github.com/docker/docker/errors"
"github.com/docker/docker/pkg/idtools"
"github.com/docker/docker/utils"
"github.com/docker/docker/volume"
)
// VolumeDataPathName is the name of the directory where the volume data is stored.
// It uses a very distinctive name to avoid collisions migrating data between
// Docker versions.
const (
VolumeDataPathName = "_data"
volumesPathName = "volumes"
)
var (
// ErrNotFound is the typed error returned when the requested volume name can't be found
ErrNotFound = errors.New("volume not found")
// volumeNameRegex ensures the name assigned for the volume is valid.
// This name is used to create the bind directory, so we need to avoid characters that
// would make the path to escape the root directory.
volumeNameRegex = utils.RestrictedVolumeNamePattern
)
// New instantiates a new Root instance with the provided scope. Scope
// is the base path that the Root instance uses to store its
// volumes. The base path is created here if it does not exist.
func New(scope string, rootUID, rootGID int) (*Root, error) {
rootDirectory := filepath.Join(scope, volumesPathName)
if err := idtools.MkdirAllAs(rootDirectory, 0700, rootUID, rootGID); err != nil {
return nil, err
}
r := &Root{
scope: scope,
path: rootDirectory,
volumes: make(map[string]*localVolume),
rootUID: rootUID,
rootGID: rootGID,
}
dirs, err := ioutil.ReadDir(rootDirectory)
if err != nil {
return nil, err
}
for _, d := range dirs {
name := filepath.Base(d.Name())
r.volumes[name] = &localVolume{
driverName: r.Name(),
name: name,
path: r.DataPath(name),
}
}
return r, nil
}
// Root implements the Driver interface for the volume package and
// manages the creation/removal of volumes. It uses only standard vfs
// commands to create/remove dirs within its provided scope.
type Root struct {
m sync.Mutex
scope string
path string
volumes map[string]*localVolume
rootUID int
rootGID int
}
// List lists all the volumes
func (r *Root) List() ([]volume.Volume, error) {
var ls []volume.Volume
for _, v := range r.volumes {
ls = append(ls, v)
}
return ls, nil
}
// DataPath returns the constructed path of this volume.
func (r *Root) DataPath(volumeName string) string {
return filepath.Join(r.path, volumeName, VolumeDataPathName)
}
// Name returns the name of Root, defined in the volume package in the DefaultDriverName constant.
func (r *Root) Name() string {
return volume.DefaultDriverName
}
// Create creates a new volume.Volume with the provided name, creating
// the underlying directory tree required for this volume in the
// process.
func (r *Root) Create(name string, _ map[string]string) (volume.Volume, error) {
if err := r.validateName(name); err != nil {
return nil, err
}
r.m.Lock()
defer r.m.Unlock()
v, exists := r.volumes[name]
if exists {
return v, nil
}
path := r.DataPath(name)
if err := idtools.MkdirAllAs(path, 0755, r.rootUID, r.rootGID); err != nil {
if os.IsExist(err) {
return nil, fmt.Errorf("volume already exists under %s", filepath.Dir(path))
}
return nil, err
}
v = &localVolume{
driverName: r.Name(),
name: name,
path: path,
}
r.volumes[name] = v
return v, nil
}
// Remove removes the specified volume and all underlying data. If the
// given volume does not belong to this driver and an error is
// returned. The volume is reference counted, if all references are
// not released then the volume is not removed.
func (r *Root) Remove(v volume.Volume) error {
r.m.Lock()
defer r.m.Unlock()
lv, ok := v.(*localVolume)
if !ok {
return errors.New("unknown volume type")
}
realPath, err := filepath.EvalSymlinks(lv.path)
if err != nil {
if !os.IsNotExist(err) {
return err
}
realPath = filepath.Dir(lv.path)
}
if !r.scopedPath(realPath) {
return fmt.Errorf("Unable to remove a directory of out the Docker root %s: %s", r.scope, realPath)
}
if err := removePath(realPath); err != nil {
return err
}
delete(r.volumes, lv.name)
return removePath(filepath.Dir(lv.path))
}
func removePath(path string) error {
if err := os.RemoveAll(path); err != nil {
if os.IsNotExist(err) {
return nil
}
return err
}
return nil
}
// Get looks up the volume for the given name and returns it if found
func (r *Root) Get(name string) (volume.Volume, error) {
r.m.Lock()
v, exists := r.volumes[name]
r.m.Unlock()
if !exists {
return nil, ErrNotFound
}
return v, nil
}
func (r *Root) validateName(name string) error {
if !volumeNameRegex.MatchString(name) {
return derr.ErrorCodeVolumeName.WithArgs(name, utils.RestrictedNameChars)
}
return nil
}
// localVolume implements the Volume interface from the volume package and
// represents the volumes created by Root.
type localVolume struct {
m sync.Mutex
usedCount int
// unique name of the volume
name string
// path is the path on the host where the data lives
path string
// driverName is the name of the driver that created the volume.
driverName string
}
// Name returns the name of the given Volume.
func (v *localVolume) Name() string {
return v.name
}
// DriverName returns the driver that created the given Volume.
func (v *localVolume) DriverName() string {
return v.driverName
}
// Path returns the data location.
func (v *localVolume) Path() string {
return v.path
}
// Mount implements the localVolume interface, returning the data location.
func (v *localVolume) Mount() (string, error) {
return v.path, nil
}
// Umount is for satisfying the localVolume interface and does not do anything in this driver.
func (v *localVolume) Unmount() error {
return nil
}