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moby--moby/layer/filestore.go
Derek McGowan 500e77bad0 Add layer store
Layer store manages read-only and read-write layers on a union file system.
Read only layers are always referenced by content addresses.
Read-write layer identifiers are handled by the caller but upon registering
its difference, the committed read-only layer will be referenced by content
hash.

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
2015-11-24 09:40:23 -08:00

318 lines
7.8 KiB
Go

package layer
import (
"compress/gzip"
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"regexp"
"strconv"
"github.com/Sirupsen/logrus"
"github.com/docker/distribution/digest"
"github.com/docker/docker/pkg/ioutils"
)
var (
stringIDRegexp = regexp.MustCompile(`^[a-f0-9]{64}(-init)?$`)
supportedAlgorithms = []digest.Algorithm{
digest.SHA256,
// digest.SHA384, // Currently not used
// digest.SHA512, // Currently not used
}
)
type fileMetadataStore struct {
root string
}
type fileMetadataTransaction struct {
store *fileMetadataStore
root string
}
// NewFSMetadataStore returns an instance of a metadata store
// which is backed by files on disk using the provided root
// as the root of metadata files.
func NewFSMetadataStore(root string) (MetadataStore, error) {
if err := os.MkdirAll(root, 0700); err != nil {
return nil, err
}
return &fileMetadataStore{
root: root,
}, nil
}
func (fms *fileMetadataStore) getLayerDirectory(layer ChainID) string {
dgst := digest.Digest(layer)
return filepath.Join(fms.root, string(dgst.Algorithm()), dgst.Hex())
}
func (fms *fileMetadataStore) getLayerFilename(layer ChainID, filename string) string {
return filepath.Join(fms.getLayerDirectory(layer), filename)
}
func (fms *fileMetadataStore) getMountDirectory(mount string) string {
return filepath.Join(fms.root, "mounts", mount)
}
func (fms *fileMetadataStore) getMountFilename(mount, filename string) string {
return filepath.Join(fms.getMountDirectory(mount), filename)
}
func (fms *fileMetadataStore) StartTransaction() (MetadataTransaction, error) {
tmpDir := filepath.Join(fms.root, "tmp")
if err := os.MkdirAll(tmpDir, 0755); err != nil {
return nil, err
}
td, err := ioutil.TempDir(tmpDir, "layer-")
if err != nil {
return nil, err
}
// Create a new tempdir
return &fileMetadataTransaction{
store: fms,
root: td,
}, nil
}
func (fm *fileMetadataTransaction) SetSize(size int64) error {
content := fmt.Sprintf("%d", size)
return ioutil.WriteFile(filepath.Join(fm.root, "size"), []byte(content), 0644)
}
func (fm *fileMetadataTransaction) SetParent(parent ChainID) error {
return ioutil.WriteFile(filepath.Join(fm.root, "parent"), []byte(digest.Digest(parent).String()), 0644)
}
func (fm *fileMetadataTransaction) SetDiffID(diff DiffID) error {
return ioutil.WriteFile(filepath.Join(fm.root, "diff"), []byte(digest.Digest(diff).String()), 0644)
}
func (fm *fileMetadataTransaction) SetCacheID(cacheID string) error {
return ioutil.WriteFile(filepath.Join(fm.root, "cache-id"), []byte(cacheID), 0644)
}
func (fm *fileMetadataTransaction) TarSplitWriter() (io.WriteCloser, error) {
f, err := os.OpenFile(filepath.Join(fm.root, "tar-split.json.gz"), os.O_TRUNC|os.O_CREATE|os.O_WRONLY, 0644)
if err != nil {
return nil, err
}
fz := gzip.NewWriter(f)
return ioutils.NewWriteCloserWrapper(fz, func() error {
fz.Close()
return f.Close()
}), nil
}
func (fm *fileMetadataTransaction) Commit(layer ChainID) error {
finalDir := fm.store.getLayerDirectory(layer)
if err := os.MkdirAll(filepath.Dir(finalDir), 0755); err != nil {
return err
}
return os.Rename(fm.root, finalDir)
}
func (fm *fileMetadataTransaction) Cancel() error {
return os.RemoveAll(fm.root)
}
func (fm *fileMetadataTransaction) String() string {
return fm.root
}
func (fms *fileMetadataStore) GetSize(layer ChainID) (int64, error) {
content, err := ioutil.ReadFile(fms.getLayerFilename(layer, "size"))
if err != nil {
return 0, err
}
size, err := strconv.ParseInt(string(content), 10, 64)
if err != nil {
return 0, err
}
return size, nil
}
func (fms *fileMetadataStore) GetParent(layer ChainID) (ChainID, error) {
content, err := ioutil.ReadFile(fms.getLayerFilename(layer, "parent"))
if err != nil {
if os.IsNotExist(err) {
return "", nil
}
return "", err
}
dgst, err := digest.ParseDigest(string(content))
if err != nil {
return "", err
}
return ChainID(dgst), nil
}
func (fms *fileMetadataStore) GetDiffID(layer ChainID) (DiffID, error) {
content, err := ioutil.ReadFile(fms.getLayerFilename(layer, "diff"))
if err != nil {
return "", err
}
dgst, err := digest.ParseDigest(string(content))
if err != nil {
return "", err
}
return DiffID(dgst), nil
}
func (fms *fileMetadataStore) GetCacheID(layer ChainID) (string, error) {
content, err := ioutil.ReadFile(fms.getLayerFilename(layer, "cache-id"))
if err != nil {
return "", err
}
if !stringIDRegexp.MatchString(string(content)) {
return "", errors.New("invalid cache id value")
}
return string(content), nil
}
func (fms *fileMetadataStore) TarSplitReader(layer ChainID) (io.ReadCloser, error) {
fz, err := os.Open(fms.getLayerFilename(layer, "tar-split.json.gz"))
if err != nil {
return nil, err
}
f, err := gzip.NewReader(fz)
if err != nil {
return nil, err
}
return ioutils.NewReadCloserWrapper(f, func() error {
f.Close()
return fz.Close()
}), nil
}
func (fms *fileMetadataStore) SetMountID(mount string, mountID string) error {
if err := os.MkdirAll(fms.getMountDirectory(mount), 0755); err != nil {
return err
}
return ioutil.WriteFile(fms.getMountFilename(mount, "mount-id"), []byte(mountID), 0644)
}
func (fms *fileMetadataStore) SetInitID(mount string, init string) error {
if err := os.MkdirAll(fms.getMountDirectory(mount), 0755); err != nil {
return err
}
return ioutil.WriteFile(fms.getMountFilename(mount, "init-id"), []byte(init), 0644)
}
func (fms *fileMetadataStore) SetMountParent(mount string, parent ChainID) error {
if err := os.MkdirAll(fms.getMountDirectory(mount), 0755); err != nil {
return err
}
return ioutil.WriteFile(fms.getMountFilename(mount, "parent"), []byte(digest.Digest(parent).String()), 0644)
}
func (fms *fileMetadataStore) GetMountID(mount string) (string, error) {
content, err := ioutil.ReadFile(fms.getMountFilename(mount, "mount-id"))
if err != nil {
return "", err
}
if !stringIDRegexp.MatchString(string(content)) {
return "", errors.New("invalid mount id value")
}
return string(content), nil
}
func (fms *fileMetadataStore) GetInitID(mount string) (string, error) {
content, err := ioutil.ReadFile(fms.getMountFilename(mount, "init-id"))
if err != nil {
if os.IsNotExist(err) {
return "", nil
}
return "", err
}
if !stringIDRegexp.MatchString(string(content)) {
return "", errors.New("invalid init id value")
}
return string(content), nil
}
func (fms *fileMetadataStore) GetMountParent(mount string) (ChainID, error) {
content, err := ioutil.ReadFile(fms.getMountFilename(mount, "parent"))
if err != nil {
if os.IsNotExist(err) {
return "", nil
}
return "", err
}
dgst, err := digest.ParseDigest(string(content))
if err != nil {
return "", err
}
return ChainID(dgst), nil
}
func (fms *fileMetadataStore) List() ([]ChainID, []string, error) {
var ids []ChainID
for _, algorithm := range supportedAlgorithms {
fileInfos, err := ioutil.ReadDir(filepath.Join(fms.root, string(algorithm)))
if err != nil {
if os.IsNotExist(err) {
continue
}
return nil, nil, err
}
for _, fi := range fileInfos {
if fi.IsDir() && fi.Name() != "mounts" {
dgst := digest.NewDigestFromHex(string(algorithm), fi.Name())
if err := dgst.Validate(); err != nil {
logrus.Debugf("Ignoring invalid digest %s:%s", algorithm, fi.Name())
} else {
ids = append(ids, ChainID(dgst))
}
}
}
}
fileInfos, err := ioutil.ReadDir(filepath.Join(fms.root, "mounts"))
if err != nil {
if os.IsNotExist(err) {
return ids, []string{}, nil
}
return nil, nil, err
}
var mounts []string
for _, fi := range fileInfos {
if fi.IsDir() {
mounts = append(mounts, fi.Name())
}
}
return ids, mounts, nil
}
func (fms *fileMetadataStore) Remove(layer ChainID) error {
return os.RemoveAll(fms.getLayerDirectory(layer))
}
func (fms *fileMetadataStore) RemoveMount(mount string) error {
return os.RemoveAll(fms.getMountDirectory(mount))
}