distribution/storagedriver/azure/azure.go

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// Package azure provides a storagedriver.StorageDriver implementation to
// store blobs in Microsoft Azure Blob Storage Service.
package azure
import (
"bytes"
"encoding/base64"
"fmt"
"io"
"io/ioutil"
"strconv"
"strings"
"github.com/docker/docker-registry/storagedriver"
"github.com/docker/docker-registry/storagedriver/factory"
azure "github.com/MSOpenTech/azure-sdk-for-go/clients/storage"
)
const driverName = "azure"
const (
paramAccountName = "accountname"
paramAccountKey = "accountkey"
paramContainer = "container"
)
// Driver is a storagedriver.StorageDriver implementation backed by
// Microsoft Azure Blob Storage Service.
type Driver struct {
client *azure.BlobStorageClient
container string
}
func init() {
factory.Register(driverName, &azureDriverFactory{})
}
type azureDriverFactory struct{}
func (factory *azureDriverFactory) Create(parameters map[string]string) (storagedriver.StorageDriver, error) {
return FromParameters(parameters)
}
// FromParameters constructs a new Driver with a given parameters map.
func FromParameters(parameters map[string]string) (*Driver, error) {
accountName, ok := parameters[paramAccountName]
if !ok {
return nil, fmt.Errorf("No %s parameter provided", paramAccountName)
}
accountKey, ok := parameters[paramAccountKey]
if !ok {
return nil, fmt.Errorf("No %s parameter provided", paramAccountKey)
}
container, ok := parameters[paramContainer]
if !ok {
return nil, fmt.Errorf("No %s parameter provided", paramContainer)
}
return New(accountName, accountKey, container)
}
// New constructs a new Driver with the given Azure Storage Account credentials
func New(accountName, accountKey, container string) (*Driver, error) {
api, err := azure.NewBasicClient(accountName, accountKey)
if err != nil {
return nil, err
}
blobClient := api.GetBlobService()
// Create registry container
if _, err = blobClient.CreateContainerIfNotExists(container, azure.ContainerAccessTypePrivate); err != nil {
return nil, err
}
return &Driver{
client: blobClient,
container: container}, nil
}
// Implement the storagedriver.StorageDriver interface.
// GetContent retrieves the content stored at "path" as a []byte.
func (d *Driver) GetContent(path string) ([]byte, error) {
blob, err := d.client.GetBlob(d.container, path)
if err != nil {
if is404(err) {
return nil, storagedriver.PathNotFoundError{Path: path}
}
return nil, err
}
return ioutil.ReadAll(blob)
}
// PutContent stores the []byte content at a location designated by "path".
func (d *Driver) PutContent(path string, contents []byte) error {
return d.client.PutBlockBlob(d.container, path, ioutil.NopCloser(bytes.NewReader(contents)))
}
// ReadStream retrieves an io.ReadCloser for the content stored at "path" with a
// given byte offset.
func (d *Driver) ReadStream(path string, offset int64) (io.ReadCloser, error) {
if ok, err := d.client.BlobExists(d.container, path); err != nil {
return nil, err
} else if !ok {
return nil, storagedriver.PathNotFoundError{Path: path}
}
size, err := d.CurrentSize(path)
if err != nil {
return nil, err
}
if offset >= int64(size) {
return nil, storagedriver.InvalidOffsetError{Path: path, Offset: offset}
}
bytesRange := fmt.Sprintf("%v-", offset)
resp, err := d.client.GetBlobRange(d.container, path, bytesRange)
if err != nil {
return nil, err
}
return resp, nil
}
// WriteStream stores the contents of the provided io.ReadCloser at a location
// designated by the given path.
func (d *Driver) WriteStream(path string, offset, size int64, reader io.ReadCloser) error {
var (
lastBlockNum int
resumableOffset int64
blocks []azure.Block
)
if blobExists, err := d.client.BlobExists(d.container, path); err != nil {
return err
} else if !blobExists { // new blob
lastBlockNum = 0
resumableOffset = 0
} else { // append
if parts, err := d.client.GetBlockList(d.container, path, azure.BlockListTypeCommitted); err != nil {
return err
} else if len(parts.CommittedBlocks) == 0 {
lastBlockNum = 0
resumableOffset = 0
} else {
lastBlock := parts.CommittedBlocks[len(parts.CommittedBlocks)-1]
if lastBlockNum, err = blockNum(lastBlock.Name); err != nil {
return fmt.Errorf("Cannot parse block name as number '%s': %s", lastBlock.Name, err.Error())
}
var totalSize int64
for _, v := range parts.CommittedBlocks {
blocks = append(blocks, azure.Block{
Id: v.Name,
Status: azure.BlockStatusCommitted})
totalSize += int64(v.Size)
}
// NOTE: Azure driver currently supports only append mode (resumable
// index is exactly where the committed blocks of the blob end).
// In order to support writing to offsets other than last index,
// adjacent blocks overlapping with the [offset:offset+size] area
// must be fetched, splitted and should be overwritten accordingly.
// As the current use of this method is append only, that implementation
// is omitted.
resumableOffset = totalSize
}
}
if offset != resumableOffset {
return storagedriver.InvalidOffsetError{Path: path, Offset: offset}
}
// Put content
buf := make([]byte, azure.MaxBlobBlockSize)
for {
// Read chunks of exactly size N except the last chunk to
// maximize block size and minimize block count.
n, err := io.ReadFull(reader, buf)
if err == io.EOF {
break
}
data := buf[:n]
blockID := toBlockID(lastBlockNum + 1)
if err = d.client.PutBlock(d.container, path, blockID, data); err != nil {
return err
}
blocks = append(blocks, azure.Block{
Id: blockID,
Status: azure.BlockStatusLatest})
lastBlockNum++
}
// Commit block list
return d.client.PutBlockList(d.container, path, blocks)
}
// CurrentSize retrieves the curernt size in bytes of the object at the given
// path.
func (d *Driver) CurrentSize(path string) (uint64, error) {
props, err := d.client.GetBlobProperties(d.container, path)
if err != nil {
return 0, err
}
return props.ContentLength, nil
}
// List returns a list of the objects that are direct descendants of the given
// path.
func (d *Driver) List(path string) ([]string, error) {
if path == "/" {
path = ""
}
blobs, err := d.listBlobs(d.container, path)
if err != nil {
return blobs, err
}
list := directDescendants(blobs, path)
return list, nil
}
// Move moves an object stored at sourcePath to destPath, removing the original
// object.
func (d *Driver) Move(sourcePath string, destPath string) error {
sourceBlobURL := d.client.GetBlobUrl(d.container, sourcePath)
err := d.client.CopyBlob(d.container, destPath, sourceBlobURL)
if err != nil {
if is404(err) {
return storagedriver.PathNotFoundError{Path: sourcePath}
}
return err
}
return d.client.DeleteBlob(d.container, sourcePath)
}
// Delete recursively deletes all objects stored at "path" and its subpaths.
func (d *Driver) Delete(path string) error {
ok, err := d.client.DeleteBlobIfExists(d.container, path)
if err != nil {
return err
}
if ok {
return nil // was a blob and deleted, return
}
// Not a blob, see if path is a virtual container with blobs
blobs, err := d.listBlobs(d.container, path)
if err != nil {
return err
}
for _, b := range blobs {
if err = d.client.DeleteBlob(d.container, b); err != nil {
return err
}
}
if len(blobs) == 0 {
return storagedriver.PathNotFoundError{Path: path}
}
return nil
}
// directDescendants will find direct descendants (blobs or virtual containers)
// of from list of blob paths and will return their full paths. Elements in blobs
// list must be prefixed with a "/" and
//
// Example: direct descendants of "/" in {"/foo", "/bar/1", "/bar/2"} is
// {"/foo", "/bar"} and direct descendants of "bar" is {"/bar/1", "/bar/2"}
func directDescendants(blobs []string, prefix string) []string {
if !strings.HasPrefix(prefix, "/") { // add trailing '/'
prefix = "/" + prefix
}
if !strings.HasSuffix(prefix, "/") { // containerify the path
prefix += "/"
}
out := make(map[string]bool)
for _, b := range blobs {
if strings.HasPrefix(b, prefix) {
rel := b[len(prefix):]
c := strings.Count(rel, "/")
if c == 0 {
out[b] = true
} else {
out[prefix+rel[:strings.Index(rel, "/")]] = true
}
}
}
var keys []string
for k := range out {
keys = append(keys, k)
}
return keys
}
func (d *Driver) listBlobs(container, virtPath string) ([]string, error) {
if virtPath != "" && !strings.HasSuffix(virtPath, "/") { // containerify the path
virtPath += "/"
}
out := []string{}
marker := ""
for {
resp, err := d.client.ListBlobs(d.container, azure.ListBlobsParameters{
Marker: marker,
Prefix: virtPath,
})
if err != nil {
return out, err
}
for _, b := range resp.Blobs {
out = append(out, b.Name)
}
if len(resp.Blobs) == 0 || resp.NextMarker == "" {
break
}
marker = resp.NextMarker
}
return out, nil
}
func is404(err error) bool {
e, ok := err.(azure.StorageServiceError)
return ok && e.StatusCode == 404
}
func blockNum(b64Name string) (int, error) {
s, err := base64.StdEncoding.DecodeString(b64Name)
if err != nil {
return 0, err
}
return strconv.Atoi(string(s))
}
func toBlockID(i int) string {
return base64.StdEncoding.EncodeToString([]byte(strconv.Itoa(i)))
}