229 lines
5.6 KiB
Go
229 lines
5.6 KiB
Go
// Package local provides the default implementation for volumes. It
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// is used to mount data volume containers and directories local to
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// the host server.
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package local
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import (
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"errors"
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"fmt"
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"io/ioutil"
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"os"
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"path/filepath"
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"strings"
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"sync"
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"github.com/docker/docker/volume"
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)
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// VolumeDataPathName is the name of the directory where the volume data is stored.
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// It uses a very distintive name to avoid collisions migrating data between
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// Docker versions.
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const (
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VolumeDataPathName = "_data"
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volumesPathName = "volumes"
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)
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var (
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// ErrNotFound is the typed error returned when the requested volume name can't be found
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ErrNotFound = errors.New("volume not found")
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oldVfsDir = filepath.Join("vfs", "dir")
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)
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// New instantiates a new Root instance with the provided scope. Scope
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// is the base path that the Root instance uses to store its
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// volumes. The base path is created here if it does not exist.
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func New(scope string) (*Root, error) {
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rootDirectory := filepath.Join(scope, volumesPathName)
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if err := os.MkdirAll(rootDirectory, 0700); err != nil {
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return nil, err
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}
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r := &Root{
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scope: scope,
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path: rootDirectory,
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volumes: make(map[string]*localVolume),
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}
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dirs, err := ioutil.ReadDir(rootDirectory)
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if err != nil {
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return nil, err
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}
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for _, d := range dirs {
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name := filepath.Base(d.Name())
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r.volumes[name] = &localVolume{
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driverName: r.Name(),
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name: name,
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path: r.DataPath(name),
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}
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}
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return r, nil
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}
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// Root implements the Driver interface for the volume package and
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// manages the creation/removal of volumes. It uses only standard vfs
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// commands to create/remove dirs within its provided scope.
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type Root struct {
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m sync.Mutex
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scope string
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path string
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volumes map[string]*localVolume
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}
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// List lists all the volumes
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func (r *Root) List() []volume.Volume {
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var ls []volume.Volume
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for _, v := range r.volumes {
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ls = append(ls, v)
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}
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return ls
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}
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// DataPath returns the constructed path of this volume.
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func (r *Root) DataPath(volumeName string) string {
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return filepath.Join(r.path, volumeName, VolumeDataPathName)
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}
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// Name returns the name of Root, defined in the volume package in the DefaultDriverName constant.
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func (r *Root) Name() string {
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return volume.DefaultDriverName
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}
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// Create creates a new volume.Volume with the provided name, creating
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// the underlying directory tree required for this volume in the
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// process.
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func (r *Root) Create(name string, _ map[string]string) (volume.Volume, error) {
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r.m.Lock()
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defer r.m.Unlock()
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v, exists := r.volumes[name]
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if exists {
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return v, nil
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}
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path := r.DataPath(name)
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if err := os.MkdirAll(path, 0755); err != nil {
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if os.IsExist(err) {
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return nil, fmt.Errorf("volume already exists under %s", filepath.Dir(path))
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}
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return nil, err
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}
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v = &localVolume{
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driverName: r.Name(),
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name: name,
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path: path,
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}
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r.volumes[name] = v
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return v, nil
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}
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// Remove removes the specified volume and all underlying data. If the
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// given volume does not belong to this driver and an error is
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// returned. The volume is reference counted, if all references are
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// not released then the volume is not removed.
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func (r *Root) Remove(v volume.Volume) error {
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r.m.Lock()
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defer r.m.Unlock()
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lv, ok := v.(*localVolume)
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if !ok {
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return errors.New("unknown volume type")
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}
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realPath, err := filepath.EvalSymlinks(lv.path)
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if err != nil {
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if !os.IsNotExist(err) {
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return err
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}
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realPath = filepath.Dir(lv.path)
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}
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if !r.scopedPath(realPath) {
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return fmt.Errorf("Unable to remove a directory of out the Docker root %s: %s", r.scope, realPath)
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}
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if err := removePath(realPath); err != nil {
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return err
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}
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delete(r.volumes, lv.name)
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return removePath(filepath.Dir(lv.path))
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}
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func removePath(path string) error {
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if err := os.RemoveAll(path); err != nil {
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if os.IsNotExist(err) {
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return nil
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}
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return err
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}
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return nil
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}
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// Get looks up the volume for the given name and returns it if found
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func (r *Root) Get(name string) (volume.Volume, error) {
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r.m.Lock()
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v, exists := r.volumes[name]
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r.m.Unlock()
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if !exists {
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return nil, ErrNotFound
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}
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return v, nil
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}
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// scopedPath verifies that the path where the volume is located
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// is under Docker's root and the valid local paths.
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func (r *Root) scopedPath(realPath string) bool {
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// Volumes path for Docker version >= 1.7
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if strings.HasPrefix(realPath, filepath.Join(r.scope, volumesPathName)) && realPath != filepath.Join(r.scope, volumesPathName) {
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return true
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}
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// Volumes path for Docker version < 1.7
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if strings.HasPrefix(realPath, filepath.Join(r.scope, oldVfsDir)) {
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return true
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}
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return false
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}
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// localVolume implements the Volume interface from the volume package and
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// represents the volumes created by Root.
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type localVolume struct {
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m sync.Mutex
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usedCount int
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// unique name of the volume
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name string
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// path is the path on the host where the data lives
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path string
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// driverName is the name of the driver that created the volume.
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driverName string
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}
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// Name returns the name of the given Volume.
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func (v *localVolume) Name() string {
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return v.name
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}
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// DriverName returns the driver that created the given Volume.
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func (v *localVolume) DriverName() string {
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return v.driverName
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}
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// Path returns the data location.
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func (v *localVolume) Path() string {
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return v.path
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}
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// Mount implements the localVolume interface, returning the data location.
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func (v *localVolume) Mount() (string, error) {
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return v.path, nil
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}
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// Umount is for satisfying the localVolume interface and does not do anything in this driver.
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func (v *localVolume) Unmount() error {
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return nil
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}
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