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moby--moby/volume/volume.go
Brian Goff 6d98e344c7 revendor engine-api
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
2016-08-16 14:16:12 -04:00

191 lines
5.9 KiB
Go

package volume
import (
"fmt"
"os"
"strings"
"syscall"
"github.com/docker/docker/pkg/stringid"
"github.com/docker/docker/pkg/system"
mounttypes "github.com/docker/engine-api/types/mount"
"github.com/opencontainers/runc/libcontainer/label"
)
// DefaultDriverName is the driver name used for the driver
// implemented in the local package.
const DefaultDriverName = "local"
// Scopes define if a volume has is cluster-wide (global) or local only.
// Scopes are returned by the volume driver when it is queried for capabilities and then set on a volume
const (
LocalScope = "local"
GlobalScope = "global"
)
// Driver is for creating and removing volumes.
type Driver interface {
// Name returns the name of the volume driver.
Name() string
// Create makes a new volume with the given id.
Create(name string, opts map[string]string) (Volume, error)
// Remove deletes the volume.
Remove(vol Volume) (err error)
// List lists all the volumes the driver has
List() ([]Volume, error)
// Get retrieves the volume with the requested name
Get(name string) (Volume, error)
// Scope returns the scope of the driver (e.g. `global` or `local`).
// Scope determines how the driver is handled at a cluster level
Scope() string
}
// Capability defines a set of capabilities that a driver is able to handle.
type Capability struct {
// Scope is the scope of the driver, `global` or `local`
// A `global` scope indicates that the driver manages volumes across the cluster
// A `local` scope indicates that the driver only manages volumes resources local to the host
// Scope is declared by the driver
Scope string
}
// Volume is a place to store data. It is backed by a specific driver, and can be mounted.
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(id string) (string, error)
// Unmount unmounts the volume when it is no longer in use.
Unmount(id string) error
// Status returns low-level status information about a volume
Status() map[string]interface{}
}
// LabeledVolume wraps a Volume with user-defined labels
type LabeledVolume interface {
Labels() map[string]string
Volume
}
// ScopedVolume wraps a volume with a cluster scope (e.g., `local` or `global`)
type ScopedVolume interface {
Scope() string
Volume
}
// MountPoint is the intersection point between a volume and a container. It
// specifies which volume is to be used and where inside a container it should
// be mounted.
type MountPoint struct {
Source string // Container host directory
Destination string // Inside the container
RW bool // True if writable
Name string // Name set by user
Driver string // Volume driver to use
Volume Volume `json:"-"`
// Note Mode is not used on Windows
Mode string `json:"Relabel"` // Originally field was `Relabel`"
// Note Propagation is not used on Windows
Propagation mounttypes.Propagation // Mount propagation string
Named bool // specifies if the mountpoint was specified by name
// Specifies if data should be copied from the container before the first mount
// Use a pointer here so we can tell if the user set this value explicitly
// This allows us to error out when the user explicitly enabled copy but we can't copy due to the volume being populated
CopyData bool `json:"-"`
// ID is the opaque ID used to pass to the volume driver.
// This should be set by calls to `Mount` and unset by calls to `Unmount`
ID string
}
// Setup sets up a mount point by either mounting the volume if it is
// configured, or creating the source directory if supplied.
func (m *MountPoint) Setup(mountLabel string) (string, error) {
if m.Volume != nil {
if m.ID == "" {
m.ID = stringid.GenerateNonCryptoID()
}
return m.Volume.Mount(m.ID)
}
if len(m.Source) == 0 {
return "", fmt.Errorf("Unable to setup mount point, neither source nor volume defined")
}
// system.MkdirAll() produces an error if m.Source exists and is a file (not a directory),
if err := system.MkdirAll(m.Source, 0755); err != nil {
if perr, ok := err.(*os.PathError); ok {
if perr.Err != syscall.ENOTDIR {
return "", err
}
}
}
if label.RelabelNeeded(m.Mode) {
if err := label.Relabel(m.Source, mountLabel, label.IsShared(m.Mode)); err != nil {
return "", err
}
}
return m.Source, nil
}
// Path returns the path of a volume in a mount point.
func (m *MountPoint) Path() string {
if m.Volume != nil {
return m.Volume.Path()
}
return m.Source
}
// Type returns the type of mount point
func (m *MountPoint) Type() string {
if m.Name != "" {
return "volume"
}
if m.Source != "" {
return "bind"
}
return "ephemeral"
}
// ParseVolumesFrom ensures that the supplied volumes-from is valid.
func ParseVolumesFrom(spec string) (string, string, error) {
if len(spec) == 0 {
return "", "", fmt.Errorf("volumes-from specification cannot be an empty string")
}
specParts := strings.SplitN(spec, ":", 2)
id := specParts[0]
mode := "rw"
if len(specParts) == 2 {
mode = specParts[1]
if !ValidMountMode(mode) {
return "", "", errInvalidMode(mode)
}
// For now don't allow propagation properties while importing
// volumes from data container. These volumes will inherit
// the same propagation property as of the original volume
// in data container. This probably can be relaxed in future.
if HasPropagation(mode) {
return "", "", errInvalidMode(mode)
}
// Do not allow copy modes on volumes-from
if _, isSet := getCopyMode(mode); isSet {
return "", "", errInvalidMode(mode)
}
}
return id, mode, nil
}
func errInvalidMode(mode string) error {
return fmt.Errorf("invalid mode: %v", mode)
}
func errInvalidSpec(spec string) error {
return fmt.Errorf("Invalid volume specification: '%s'", spec)
}