package volume import ( "fmt" "os" "path/filepath" "syscall" "time" mounttypes "github.com/docker/docker/api/types/mount" "github.com/docker/docker/pkg/idtools" "github.com/docker/docker/pkg/stringid" "github.com/opencontainers/selinux/go-selinux/label" "github.com/pkg/errors" ) // 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 name. 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 // CreatedAt returns Volume Creation time CreatedAt() (time.Time, error) // Status returns low-level status information about a volume Status() map[string]interface{} } // DetailedVolume wraps a Volume with user-defined labels, options, and cluster scope (e.g., `local` or `global`) type DetailedVolume interface { Labels() map[string]string Options() map[string]string 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 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` 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 `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 // 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) { 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") } // system.MkdirAll() produces an error if m.Source exists and is a file (not a directory), 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) }