Volumes refactor and external plugin implementation.

Signed by all authors:

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Signed-off-by: Arnaud Porterie <arnaud.porterie@docker.com>
Signed-off-by: David Calavera <david.calavera@gmail.com>
Signed-off-by: Jeff Lindsay <progrium@gmail.com>
Signed-off-by: Alexander Morozov <lk4d4@docker.com>
Signed-off-by: Luke Marsden <luke@clusterhq.com>
Signed-off-by: David Calavera <david.calavera@gmail.com>

volume/drivers/adapter.go

@@ -0,0 +1,51 @@
+package volumedrivers
+
+import "github.com/docker/docker/volume"
+
+type volumeDriverAdapter struct {
+	name  string
+	proxy *volumeDriverProxy
+}
+
+func (a *volumeDriverAdapter) Name() string {
+	return a.name
+}
+
+func (a *volumeDriverAdapter) Create(name string) (volume.Volume, error) {
+	err := a.proxy.Create(name)
+	if err != nil {
+		return nil, err
+	}
+	return &volumeAdapter{a.proxy, name, a.name}, nil
+}
+
+func (a *volumeDriverAdapter) Remove(v volume.Volume) error {
+	return a.proxy.Remove(v.Name())
+}
+
+type volumeAdapter struct {
+	proxy      *volumeDriverProxy
+	name       string
+	driverName string
+}
+
+func (a *volumeAdapter) Name() string {
+	return a.name
+}
+
+func (a *volumeAdapter) DriverName() string {
+	return a.driverName
+}
+
+func (a *volumeAdapter) Path() string {
+	m, _ := a.proxy.Path(a.name)
+	return m
+}
+
+func (a *volumeAdapter) Mount() (string, error) {
+	return a.proxy.Mount(a.name)
+}
+
+func (a *volumeAdapter) Unmount() error {
+	return a.proxy.Unmount(a.name)
+}

volume/drivers/api.go

@@ -0,0 +1,20 @@
+package volumedrivers
+
+import "github.com/docker/docker/volume"
+
+type client interface {
+	Call(string, interface{}, interface{}) error
+}
+
+func NewVolumeDriver(name string, c client) volume.Driver {
+	proxy := &volumeDriverProxy{c}
+	return &volumeDriverAdapter{name, proxy}
+}
+
+type VolumeDriver interface {
+	Create(name string) (err error)
+	Remove(name string) (err error)
+	Path(name string) (mountpoint string, err error)
+	Mount(name string) (mountpoint string, err error)
+	Unmount(name string) (err error)
+}

volume/drivers/extpoint.go

@@ -0,0 +1,61 @@
+package volumedrivers
+
+import (
+	"sync"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/docker/docker/pkg/plugins"
+	"github.com/docker/docker/volume"
+)
+
+// currently created by hand. generation tool would generate this like:
+// $ extpoint-gen Driver > volume/extpoint.go
+
+var drivers = &driverExtpoint{extensions: make(map[string]volume.Driver)}
+
+type driverExtpoint struct {
+	extensions map[string]volume.Driver
+	sync.Mutex
+}
+
+func Register(extension volume.Driver, name string) bool {
+	drivers.Lock()
+	defer drivers.Unlock()
+	if name == "" {
+		return false
+	}
+	_, exists := drivers.extensions[name]
+	if exists {
+		return false
+	}
+	drivers.extensions[name] = extension
+	return true
+}
+
+func Unregister(name string) bool {
+	drivers.Lock()
+	defer drivers.Unlock()
+	_, exists := drivers.extensions[name]
+	if !exists {
+		return false
+	}
+	delete(drivers.extensions, name)
+	return true
+}
+
+func Lookup(name string) volume.Driver {
+	drivers.Lock()
+	defer drivers.Unlock()
+	ext, ok := drivers.extensions[name]
+	if ok {
+		return ext
+	}
+	pl, err := plugins.Get(name, "VolumeDriver")
+	if err != nil {
+		logrus.Errorf("Error: %v", err)
+		return nil
+	}
+	d := NewVolumeDriver(name, pl.Client)
+	drivers.extensions[name] = d
+	return d
+}

volume/drivers/proxy.go

@@ -0,0 +1,65 @@
+package volumedrivers
+
+// currently created by hand. generation tool would generate this like:
+// $ rpc-gen volume/drivers/api.go VolumeDriver > volume/drivers/proxy.go
+
+type volumeDriverRequest struct {
+	Name string
+}
+
+type volumeDriverResponse struct {
+	Mountpoint string `json:",ommitempty"`
+	Err        error  `json:",ommitempty"`
+}
+
+type volumeDriverProxy struct {
+	c client
+}
+
+func (pp *volumeDriverProxy) Create(name string) error {
+	args := volumeDriverRequest{name}
+	var ret volumeDriverResponse
+	err := pp.c.Call("VolumeDriver.Create", args, &ret)
+	if err != nil {
+		return err
+	}
+	return ret.Err
+}
+
+func (pp *volumeDriverProxy) Remove(name string) error {
+	args := volumeDriverRequest{name}
+	var ret volumeDriverResponse
+	err := pp.c.Call("VolumeDriver.Remove", args, &ret)
+	if err != nil {
+		return err
+	}
+	return ret.Err
+}
+
+func (pp *volumeDriverProxy) Path(name string) (string, error) {
+	args := volumeDriverRequest{name}
+	var ret volumeDriverResponse
+	if err := pp.c.Call("VolumeDriver.Path", args, &ret); err != nil {
+		return "", err
+	}
+	return ret.Mountpoint, ret.Err
+}
+
+func (pp *volumeDriverProxy) Mount(name string) (string, error) {
+	args := volumeDriverRequest{name}
+	var ret volumeDriverResponse
+	if err := pp.c.Call("VolumeDriver.Mount", args, &ret); err != nil {
+		return "", err
+	}
+	return ret.Mountpoint, ret.Err
+}
+
+func (pp *volumeDriverProxy) Unmount(name string) error {
+	args := volumeDriverRequest{name}
+	var ret volumeDriverResponse
+	err := pp.c.Call("VolumeDriver.Unmount", args, &ret)
+	if err != nil {
+		return err
+	}
+	return ret.Err
+}

volume/local/local.go

@@ -0,0 +1,126 @@
+package local
+
+import (
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sync"
+
+	"github.com/docker/docker/volume"
+)
+
+func New(rootDirectory string) (*Root, error) {
+	if err := os.MkdirAll(rootDirectory, 0700); err != nil {
+		return nil, err
+	}
+	r := &Root{
+		path:    rootDirectory,
+		volumes: make(map[string]*Volume),
+	}
+	dirs, err := ioutil.ReadDir(rootDirectory)
+	if err != nil {
+		return nil, err
+	}
+	for _, d := range dirs {
+		name := filepath.Base(d.Name())
+		r.volumes[name] = &Volume{
+			driverName: r.Name(),
+			name:       name,
+			path:       filepath.Join(rootDirectory, name),
+		}
+	}
+	return r, nil
+}
+
+type Root struct {
+	m       sync.Mutex
+	path    string
+	volumes map[string]*Volume
+}
+
+func (r *Root) Name() string {
+	return "local"
+}
+
+func (r *Root) Create(name string) (volume.Volume, error) {
+	r.m.Lock()
+	defer r.m.Unlock()
+	v, exists := r.volumes[name]
+	if !exists {
+		path := filepath.Join(r.path, name)
+		if err := os.Mkdir(path, 0755); err != nil {
+			if os.IsExist(err) {
+				return nil, fmt.Errorf("volume already exists under %s", path)
+			}
+			return nil, err
+		}
+		v = &Volume{
+			driverName: r.Name(),
+			name:       name,
+			path:       path,
+		}
+		r.volumes[name] = v
+	}
+	v.use()
+	return v, nil
+}
+
+func (r *Root) Remove(v volume.Volume) error {
+	r.m.Lock()
+	defer r.m.Unlock()
+	lv, ok := v.(*Volume)
+	if !ok {
+		return errors.New("unknown volume type")
+	}
+	lv.release()
+	if lv.usedCount == 0 {
+		delete(r.volumes, lv.name)
+		return os.RemoveAll(lv.path)
+	}
+	return nil
+}
+
+type Volume 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
+}
+
+func (v *Volume) Name() string {
+	return v.name
+}
+
+func (v *Volume) DriverName() string {
+	return v.driverName
+}
+
+func (v *Volume) Path() string {
+	return v.path
+}
+
+func (v *Volume) Mount() (string, error) {
+	return v.path, nil
+}
+
+func (v *Volume) Unmount() error {
+	return nil
+}
+
+func (v *Volume) use() {
+	v.m.Lock()
+	v.usedCount++
+	v.m.Unlock()
+}
+
+func (v *Volume) release() {
+	v.m.Lock()
+	v.usedCount--
+	v.m.Unlock()
+}

volume/volume.go

@@ -0,0 +1,26 @@
+package volume
+
+const DefaultDriverName = "local"
+
+type Driver interface {
+	// Name returns the name of the volume driver.
+	Name() string
+	// Create makes a new volume with the given id.
+	Create(string) (Volume, error)
+	// Remove deletes the volume.
+	Remove(Volume) error
+}
+
+type Volume interface {
+	// Name returns the name of the volume
+	Name() string
+	// DriverName returns the name of the driver which owns this volume.
+	DriverName() string
+	// Path returns the absolute path to the volume.
+	Path() string
+	// Mount mounts the volume and returns the absolute path to
+	// where it can be consumed.
+	Mount() (string, error)
+	// Unmount unmounts the volume when it is no longer in use.
+	Unmount() error
+}