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azure.go
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azure.go
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package azure
import (
"bytes"
"context"
"crypto/md5"
"encoding/base64"
"fmt"
"hash"
"io"
"net/http"
"path"
"strings"
"github.com/restic/restic/internal/backend"
"github.com/restic/restic/internal/backend/layout"
"github.com/restic/restic/internal/backend/location"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/restic"
"github.com/Azure/azure-sdk-for-go/sdk/azcore"
"github.com/Azure/azure-sdk-for-go/sdk/azcore/streaming"
"github.com/Azure/azure-sdk-for-go/sdk/azidentity"
"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob"
"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/blob"
"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/bloberror"
"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/blockblob"
azContainer "github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/container"
)
// Backend stores data on an azure endpoint.
type Backend struct {
cfg Config
container *azContainer.Client
connections uint
prefix string
listMaxItems int
layout.Layout
}
const saveLargeSize = 256 * 1024 * 1024
const defaultListMaxItems = 5000
// make sure that *Backend implements backend.Backend
var _ restic.Backend = &Backend{}
func NewFactory() location.Factory {
return location.NewHTTPBackendFactory("azure", ParseConfig, location.NoPassword, Create, Open)
}
func open(cfg Config, rt http.RoundTripper) (*Backend, error) {
debug.Log("open, config %#v", cfg)
var client *azContainer.Client
var err error
var endpointSuffix string
if cfg.EndpointSuffix != "" {
endpointSuffix = cfg.EndpointSuffix
} else {
endpointSuffix = "core.windows.net"
}
url := fmt.Sprintf("https://%s.blob.%s/%s", cfg.AccountName, endpointSuffix, cfg.Container)
opts := &azContainer.ClientOptions{
ClientOptions: azcore.ClientOptions{
Transport: &http.Client{Transport: rt},
},
}
if cfg.AccountKey.String() != "" {
// We have an account key value, find the BlobServiceClient
// from with a BasicClient
debug.Log(" - using account key")
cred, err := azblob.NewSharedKeyCredential(cfg.AccountName, cfg.AccountKey.Unwrap())
if err != nil {
return nil, errors.Wrap(err, "NewSharedKeyCredential")
}
client, err = azContainer.NewClientWithSharedKeyCredential(url, cred, opts)
if err != nil {
return nil, errors.Wrap(err, "NewClientWithSharedKeyCredential")
}
} else if cfg.AccountSAS.String() != "" {
// Get the client using the SAS Token as authentication, this
// is longer winded than above because the SDK wants a URL for the Account
// if your using a SAS token, and not just the account name
// we (as per the SDK ) assume the default Azure portal.
// https://github.com/Azure/azure-storage-blob-go/issues/130
debug.Log(" - using sas token")
sas := cfg.AccountSAS.Unwrap()
// strip query sign prefix
if sas[0] == '?' {
sas = sas[1:]
}
urlWithSAS := fmt.Sprintf("%s?%s", url, sas)
client, err = azContainer.NewClientWithNoCredential(urlWithSAS, opts)
if err != nil {
return nil, errors.Wrap(err, "NewAccountSASClientFromEndpointToken")
}
} else {
debug.Log(" - using DefaultAzureCredential")
cred, err := azidentity.NewDefaultAzureCredential(nil)
if err != nil {
return nil, errors.Wrap(err, "NewDefaultAzureCredential")
}
client, err = azContainer.NewClient(url, cred, opts)
if err != nil {
return nil, errors.Wrap(err, "NewClient")
}
}
be := &Backend{
container: client,
cfg: cfg,
connections: cfg.Connections,
Layout: &layout.DefaultLayout{
Path: cfg.Prefix,
Join: path.Join,
},
listMaxItems: defaultListMaxItems,
}
return be, nil
}
// Open opens the Azure backend at specified container.
func Open(_ context.Context, cfg Config, rt http.RoundTripper) (*Backend, error) {
return open(cfg, rt)
}
// Create opens the Azure backend at specified container and creates the container if
// it does not exist yet.
func Create(ctx context.Context, cfg Config, rt http.RoundTripper) (*Backend, error) {
be, err := open(cfg, rt)
if err != nil {
return nil, errors.Wrap(err, "open")
}
_, err = be.container.GetProperties(ctx, &azContainer.GetPropertiesOptions{})
if err != nil && bloberror.HasCode(err, bloberror.ContainerNotFound) {
_, err = be.container.Create(ctx, &azContainer.CreateOptions{})
if err != nil {
return nil, errors.Wrap(err, "container.Create")
}
} else if err != nil {
return be, err
}
return be, nil
}
// SetListMaxItems sets the number of list items to load per request.
func (be *Backend) SetListMaxItems(i int) {
be.listMaxItems = i
}
// IsNotExist returns true if the error is caused by a not existing file.
func (be *Backend) IsNotExist(err error) bool {
return bloberror.HasCode(err, bloberror.BlobNotFound)
}
// Join combines path components with slashes.
func (be *Backend) Join(p ...string) string {
return path.Join(p...)
}
func (be *Backend) Connections() uint {
return be.connections
}
// Location returns this backend's location (the container name).
func (be *Backend) Location() string {
return be.Join(be.cfg.AccountName, be.cfg.Prefix)
}
// Hasher may return a hash function for calculating a content hash for the backend
func (be *Backend) Hasher() hash.Hash {
return md5.New()
}
// HasAtomicReplace returns whether Save() can atomically replace files
func (be *Backend) HasAtomicReplace() bool {
return true
}
// Path returns the path in the bucket that is used for this backend.
func (be *Backend) Path() string {
return be.prefix
}
// Save stores data in the backend at the handle.
func (be *Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader) error {
objName := be.Filename(h)
debug.Log("InsertObject(%v, %v)", be.cfg.AccountName, objName)
var err error
if rd.Length() < saveLargeSize {
// if it's smaller than 256miB, then just create the file directly from the reader
err = be.saveSmall(ctx, objName, rd)
} else {
// otherwise use the more complicated method
err = be.saveLarge(ctx, objName, rd)
}
return err
}
func (be *Backend) saveSmall(ctx context.Context, objName string, rd restic.RewindReader) error {
blockBlobClient := be.container.NewBlockBlobClient(objName)
// upload it as a new "block", use the base64 hash for the ID
id := base64.StdEncoding.EncodeToString(rd.Hash())
buf := make([]byte, rd.Length())
_, err := io.ReadFull(rd, buf)
if err != nil {
return errors.Wrap(err, "ReadFull")
}
reader := bytes.NewReader(buf)
_, err = blockBlobClient.StageBlock(ctx, id, streaming.NopCloser(reader), &blockblob.StageBlockOptions{
TransactionalValidation: blob.TransferValidationTypeMD5(rd.Hash()),
})
if err != nil {
return errors.Wrap(err, "StageBlock")
}
blocks := []string{id}
_, err = blockBlobClient.CommitBlockList(ctx, blocks, &blockblob.CommitBlockListOptions{})
return errors.Wrap(err, "CommitBlockList")
}
func (be *Backend) saveLarge(ctx context.Context, objName string, rd restic.RewindReader) error {
blockBlobClient := be.container.NewBlockBlobClient(objName)
buf := make([]byte, 100*1024*1024)
blocks := []string{}
uploadedBytes := 0
for {
n, err := io.ReadFull(rd, buf)
if err == io.ErrUnexpectedEOF {
err = nil
}
if err == io.EOF {
// end of file reached, no bytes have been read at all
break
}
if err != nil {
return errors.Wrap(err, "ReadFull")
}
buf = buf[:n]
uploadedBytes += n
// upload it as a new "block", use the base64 hash for the ID
h := md5.Sum(buf)
id := base64.StdEncoding.EncodeToString(h[:])
reader := bytes.NewReader(buf)
debug.Log("StageBlock %v with %d bytes", id, len(buf))
_, err = blockBlobClient.StageBlock(ctx, id, streaming.NopCloser(reader), &blockblob.StageBlockOptions{
TransactionalValidation: blob.TransferValidationTypeMD5(h[:]),
})
if err != nil {
return errors.Wrap(err, "StageBlock")
}
blocks = append(blocks, id)
}
// sanity check
if uploadedBytes != int(rd.Length()) {
return errors.Errorf("wrote %d bytes instead of the expected %d bytes", uploadedBytes, rd.Length())
}
_, err := blockBlobClient.CommitBlockList(ctx, blocks, &blockblob.CommitBlockListOptions{})
debug.Log("uploaded %d parts: %v", len(blocks), blocks)
return errors.Wrap(err, "CommitBlockList")
}
// Load runs fn with a reader that yields the contents of the file at h at the
// given offset.
func (be *Backend) Load(ctx context.Context, h restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
return backend.DefaultLoad(ctx, h, length, offset, be.openReader, fn)
}
func (be *Backend) openReader(ctx context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error) {
objName := be.Filename(h)
blockBlobClient := be.container.NewBlobClient(objName)
resp, err := blockBlobClient.DownloadStream(ctx, &blob.DownloadStreamOptions{
Range: azblob.HTTPRange{
Offset: offset,
Count: int64(length),
},
})
if err != nil {
return nil, err
}
return resp.Body, err
}
// Stat returns information about a blob.
func (be *Backend) Stat(ctx context.Context, h restic.Handle) (restic.FileInfo, error) {
objName := be.Filename(h)
blobClient := be.container.NewBlobClient(objName)
props, err := blobClient.GetProperties(ctx, nil)
if err != nil {
return restic.FileInfo{}, errors.Wrap(err, "blob.GetProperties")
}
fi := restic.FileInfo{
Size: *props.ContentLength,
Name: h.Name,
}
return fi, nil
}
// Remove removes the blob with the given name and type.
func (be *Backend) Remove(ctx context.Context, h restic.Handle) error {
objName := be.Filename(h)
blob := be.container.NewBlobClient(objName)
_, err := blob.Delete(ctx, &azblob.DeleteBlobOptions{})
if be.IsNotExist(err) {
return nil
}
return errors.Wrap(err, "client.RemoveObject")
}
// List runs fn for each file in the backend which has the type t. When an
// error occurs (or fn returns an error), List stops and returns it.
func (be *Backend) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error {
prefix, _ := be.Basedir(t)
// make sure prefix ends with a slash
if !strings.HasSuffix(prefix, "/") {
prefix += "/"
}
max := int32(be.listMaxItems)
opts := &azContainer.ListBlobsFlatOptions{
MaxResults: &max,
Prefix: &prefix,
}
lister := be.container.NewListBlobsFlatPager(opts)
for lister.More() {
resp, err := lister.NextPage(ctx)
if err != nil {
return err
}
debug.Log("got %v objects", len(resp.Segment.BlobItems))
for _, item := range resp.Segment.BlobItems {
m := strings.TrimPrefix(*item.Name, prefix)
if m == "" {
continue
}
fi := restic.FileInfo{
Name: path.Base(m),
Size: *item.Properties.ContentLength,
}
if ctx.Err() != nil {
return ctx.Err()
}
err := fn(fi)
if err != nil {
return err
}
if ctx.Err() != nil {
return ctx.Err()
}
}
}
return ctx.Err()
}
// Delete removes all restic keys in the bucket. It will not remove the bucket itself.
func (be *Backend) Delete(ctx context.Context) error {
return backend.DefaultDelete(ctx, be)
}
// Close does nothing
func (be *Backend) Close() error { return nil }