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volumes.go
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volumes.go
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package daemon
import (
"errors"
"os"
"path/filepath"
"strings"
"github.com/docker/docker/container"
"github.com/docker/docker/daemon/execdriver"
derr "github.com/docker/docker/errors"
"github.com/docker/docker/volume"
"github.com/docker/engine-api/types"
containertypes "github.com/docker/engine-api/types/container"
"github.com/opencontainers/runc/libcontainer/label"
)
var (
// ErrVolumeReadonly is used to signal an error when trying to copy data into
// a volume mount that is not writable.
ErrVolumeReadonly = errors.New("mounted volume is marked read-only")
)
type mounts []execdriver.Mount
// volumeToAPIType converts a volume.Volume to the type used by the remote API
func volumeToAPIType(v volume.Volume) *types.Volume {
return &types.Volume{
Name: v.Name(),
Driver: v.DriverName(),
Mountpoint: v.Path(),
}
}
// Len returns the number of mounts. Used in sorting.
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. Used in sorting.
func (m mounts) Less(i, j int) bool {
return m.parts(i) < m.parts(j)
}
// Swap swaps two items in an array of mounts. Used in sorting
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. Used in sorting.
func (m mounts) parts(i int) int {
return strings.Count(filepath.Clean(m[i].Destination), string(os.PathSeparator))
}
// 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.
// 4. Cleanup old volumes that are about to be reassigned.
func (daemon *Daemon) registerMountPoints(container *container.Container, hostConfig *containertypes.HostConfig) error {
binds := map[string]bool{}
mountPoints := map[string]*volume.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 := volume.ParseVolumesFrom(v)
if err != nil {
return err
}
c, err := daemon.GetContainer(containerID)
if err != nil {
return err
}
for _, m := range c.MountPoints {
cp := &volume.MountPoint{
Name: m.Name,
Source: m.Source,
RW: m.RW && volume.ReadWrite(mode),
Driver: m.Driver,
Destination: m.Destination,
Propagation: m.Propagation,
}
if len(cp.Source) == 0 {
v, err := daemon.volumes.GetWithRef(cp.Name, cp.Driver, container.ID)
if err != nil {
return err
}
cp.Volume = v
}
mountPoints[cp.Destination] = cp
}
}
// 3. Read bind mounts
for _, b := range hostConfig.Binds {
// #10618
bind, err := volume.ParseMountSpec(b, hostConfig.VolumeDriver)
if err != nil {
return err
}
if binds[bind.Destination] {
return derr.ErrorCodeMountDup.WithArgs(bind.Destination)
}
if len(bind.Name) > 0 && len(bind.Driver) > 0 {
// create the volume
v, err := daemon.volumes.CreateWithRef(bind.Name, bind.Driver, container.ID, 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()
bind = setBindModeIfNull(bind)
}
if label.RelabelNeeded(bind.Mode) {
if err := label.Relabel(bind.Source, container.MountLabel, label.IsShared(bind.Mode)); err != nil {
return err
}
}
binds[bind.Destination] = true
mountPoints[bind.Destination] = bind
}
container.Lock()
// 4. Cleanup old volumes that are about to be reassigned.
for _, m := range mountPoints {
if m.BackwardsCompatible() {
if mp, exists := container.MountPoints[m.Destination]; exists && mp.Volume != nil {
daemon.volumes.Dereference(mp.Volume, container.ID)
}
}
}
container.MountPoints = mountPoints
container.Unlock()
return nil
}
// lazyInitializeVolume initializes a mountpoint's volume if needed.
// This happens after a daemon restart.
func (daemon *Daemon) lazyInitializeVolume(containerID string, m *volume.MountPoint) error {
if len(m.Driver) > 0 && m.Volume == nil {
v, err := daemon.volumes.GetWithRef(m.Name, m.Driver, containerID)
if err != nil {
return err
}
m.Volume = v
}
return nil
}