| package mounts // import "github.com/docker/docker/volume/mounts" |
| |
| import ( |
| "fmt" |
| "os" |
| "path/filepath" |
| "syscall" |
| |
| mounttypes "github.com/docker/docker/api/types/mount" |
| "github.com/docker/docker/pkg/idtools" |
| "github.com/docker/docker/pkg/stringid" |
| "github.com/docker/docker/volume" |
| "github.com/opencontainers/selinux/go-selinux/label" |
| "github.com/pkg/errors" |
| ) |
| |
| // 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. |
| // |
| // Note that this type is embedded in `container.Container` object and persisted to disk. |
| // Changes to this struct need to by synced with on disk state. |
| type MountPoint struct { |
| // Source is the source path of the mount. |
| // E.g. `mount --bind /foo /bar`, `/foo` is the `Source`. |
| Source string |
| // Destination is the path relative to the container root (`/`) to the mount point |
| // It is where the `Source` is mounted to |
| Destination string |
| // RW is set to true when the mountpoint should be mounted as read-write |
| RW bool |
| // Name is the name reference to the underlying data defined by `Source` |
| // e.g., the volume name |
| Name string |
| // Driver is the volume driver used to create the volume (if it is a volume) |
| Driver string |
| // Type of mount to use, see `Type<foo>` definitions in github.com/docker/docker/api/types/mount |
| Type mounttypes.Type `json:",omitempty"` |
| // Volume is the volume providing data to this mountpoint. |
| // This is nil unless `Type` is set to `TypeVolume` |
| Volume volume.Volume `json:"-"` |
| |
| // Mode is the comma separated list of options supplied by the user when creating |
| // the bind/volume mount. |
| // Note Mode is not used on Windows |
| Mode string `json:"Relabel,omitempty"` // Originally field was `Relabel`" |
| |
| // Propagation describes how the mounts are propagated from the host into the |
| // mount point, and vice-versa. |
| // See https://www.kernel.org/doc/Documentation/filesystems/sharedsubtree.txt |
| // Note Propagation is not used on Windows |
| Propagation mounttypes.Propagation `json:",omitempty"` // Mount propagation string |
| |
| // 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 `json:",omitempty"` |
| |
| // Sepc is a copy of the API request that created this mount. |
| Spec mounttypes.Mount |
| |
| // Some bind mounts should not be automatically created. |
| // (Some are auto-created for backwards-compatability) |
| // This is checked on the API but setting this here prevents race conditions. |
| // where a bind dir existed during validation was removed before reaching the setup code. |
| SkipMountpointCreation bool |
| |
| // Track usage of this mountpoint |
| // Specifically needed for containers which are running and calls to `docker cp` |
| // because both these actions require mounting the volumes. |
| active int |
| } |
| |
| // Cleanup frees resources used by the mountpoint |
| func (m *MountPoint) Cleanup() error { |
| if m.Volume == nil || m.ID == "" { |
| return nil |
| } |
| |
| if err := m.Volume.Unmount(m.ID); err != nil { |
| return errors.Wrapf(err, "error unmounting volume %s", m.Volume.Name()) |
| } |
| |
| m.active-- |
| if m.active == 0 { |
| m.ID = "" |
| } |
| return nil |
| } |
| |
| // Setup sets up a mount point by either mounting the volume if it is |
| // configured, or creating the source directory if supplied. |
| // The, optional, checkFun parameter allows doing additional checking |
| // before creating the source directory on the host. |
| func (m *MountPoint) Setup(mountLabel string, rootIDs idtools.IDPair, checkFun func(m *MountPoint) error) (path string, err error) { |
| if m.SkipMountpointCreation { |
| return m.Source, nil |
| } |
| |
| defer func() { |
| if err != nil || !label.RelabelNeeded(m.Mode) { |
| return |
| } |
| |
| var sourcePath string |
| sourcePath, err = filepath.EvalSymlinks(m.Source) |
| if err != nil { |
| path = "" |
| err = errors.Wrapf(err, "error evaluating symlinks from mount source %q", m.Source) |
| return |
| } |
| err = label.Relabel(sourcePath, mountLabel, label.IsShared(m.Mode)) |
| if err == syscall.ENOTSUP { |
| err = nil |
| } |
| if err != nil { |
| path = "" |
| err = errors.Wrapf(err, "error setting label on mount source '%s'", sourcePath) |
| } |
| }() |
| |
| if m.Volume != nil { |
| id := m.ID |
| if id == "" { |
| id = stringid.GenerateNonCryptoID() |
| } |
| path, err := m.Volume.Mount(id) |
| if err != nil { |
| return "", errors.Wrapf(err, "error while mounting volume '%s'", m.Source) |
| } |
| |
| m.ID = id |
| m.active++ |
| return path, nil |
| } |
| |
| if len(m.Source) == 0 { |
| return "", fmt.Errorf("Unable to setup mount point, neither source nor volume defined") |
| } |
| |
| if m.Type == mounttypes.TypeBind { |
| // Before creating the source directory on the host, invoke checkFun if it's not nil. One of |
| // the use case is to forbid creating the daemon socket as a directory if the daemon is in |
| // the process of shutting down. |
| if checkFun != nil { |
| if err := checkFun(m); err != nil { |
| return "", err |
| } |
| } |
| |
| // idtools.MkdirAllNewAs() produces an error if m.Source exists and is a file (not a directory) |
| // also, makes sure that if the directory is created, the correct remapped rootUID/rootGID will own it |
| if err := idtools.MkdirAllAndChownNew(m.Source, 0755, rootIDs); err != nil { |
| if perr, ok := err.(*os.PathError); ok { |
| if perr.Err != syscall.ENOTDIR { |
| return "", errors.Wrapf(err, "error while creating mount source path '%s'", m.Source) |
| } |
| } |
| } |
| } |
| 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 |
| } |
| |
| func errInvalidMode(mode string) error { |
| return errors.Errorf("invalid mode: %v", mode) |
| } |
| |
| func errInvalidSpec(spec string) error { |
| return errors.Errorf("invalid volume specification: '%s'", spec) |
| } |