forked from leverly/flynn
/
driver.go
126 lines (103 loc) · 2.87 KB
/
driver.go
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package graphdriver
import (
"errors"
"fmt"
"os"
"path"
"github.com/flynn/flynn/Godeps/_workspace/src/github.com/docker/docker/archive"
"github.com/flynn/flynn/Godeps/_workspace/src/github.com/docker/docker/pkg/mount"
)
type FsMagic uint64
const (
FsMagicBtrfs = FsMagic(0x9123683E)
FsMagicAufs = FsMagic(0x61756673)
)
type InitFunc func(root string, options []string) (Driver, error)
type Driver interface {
String() string
Create(id, parent string) error
Remove(id string) error
Get(id, mountLabel string) (dir string, err error)
Put(id string)
Exists(id string) bool
Status() [][2]string
Cleanup() error
}
type Differ interface {
Diff(id string) (archive.Archive, error)
Changes(id string) ([]archive.Change, error)
ApplyDiff(id string, diff archive.ArchiveReader) error
DiffSize(id string) (bytes int64, err error)
}
var (
DefaultDriver string
// All registred drivers
drivers map[string]InitFunc
// Slice of drivers that should be used in an order
priority = []string{
"aufs",
"btrfs",
"devicemapper",
"vfs",
}
ErrNotSupported = errors.New("driver not supported")
ErrPrerequisites = errors.New("prerequisites for driver not satisfied (wrong filesystem?)")
ErrIncompatibleFS = fmt.Errorf("backing file system is unsupported for this graph driver")
)
func init() {
drivers = make(map[string]InitFunc)
}
func Register(name string, initFunc InitFunc) error {
if _, exists := drivers[name]; exists {
return fmt.Errorf("Name already registered %s", name)
}
drivers[name] = initFunc
return nil
}
func GetDriver(name, home string, options []string) (Driver, error) {
if initFunc, exists := drivers[name]; exists {
return initFunc(path.Join(home, name), options)
}
return nil, ErrNotSupported
}
func New(root string, options []string) (driver Driver, err error) {
for _, name := range []string{os.Getenv("DOCKER_DRIVER"), DefaultDriver} {
if name != "" {
return GetDriver(name, root, options)
}
}
// Check for priority drivers first
for _, name := range priority {
driver, err = GetDriver(name, root, options)
if err != nil {
if err == ErrNotSupported || err == ErrPrerequisites || err == ErrIncompatibleFS {
continue
}
return nil, err
}
return driver, nil
}
// Check all registered drivers if no priority driver is found
for _, initFunc := range drivers {
if driver, err = initFunc(root, options); err != nil {
if err == ErrNotSupported || err == ErrPrerequisites || err == ErrIncompatibleFS {
continue
}
return nil, err
}
return driver, nil
}
return nil, fmt.Errorf("No supported storage backend found")
}
func MakePrivate(mountPoint string) error {
mounted, err := mount.Mounted(mountPoint)
if err != nil {
return err
}
if !mounted {
if err := mount.Mount(mountPoint, mountPoint, "none", "bind,rw"); err != nil {
return err
}
}
return mount.ForceMount("", mountPoint, "none", "private")
}