Merge pull request #1827 from restic/azure-large-files

azure: Support uploading large files

changelog/unreleased/issue-1822

@@ -0,0 +1,9 @@
+Bugfix: Allow uploading large files to MS Azure
+
+Sometimes, restic creates files to be uploaded to the repository which are
+quite large, e.g. when saving directories with many entries or very large
+files. The MS Azure API does not allow uploading files larger that 256MiB
+directly, rather restic needs to upload them in blocks of 100MiB. This is now
+implemented.
+
+https://github.com/restic/restic/issues/1822

internal/backend/azure/azure.go

@@ -2,6 +2,7 @@ package azure
 
 import (
 	"context"
+	"encoding/base64"
 	"io"
 	"io/ioutil"
 	"net/http"
@@ -64,13 +65,13 @@ func open(cfg Config, rt http.RoundTripper) (*Backend, error) {
 }
 
 // Open opens the Azure backend at specified container.
-func Open(cfg Config, rt http.RoundTripper) (restic.Backend, error) {
+func Open(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(cfg Config, rt http.RoundTripper) (restic.Backend, error) {
+func Create(cfg Config, rt http.RoundTripper) (*Backend, error) {
 	be, err := open(cfg, rt)
 
 	if err != nil {
@@ -129,8 +130,18 @@ func (be *Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindRe
 
 	debug.Log("InsertObject(%v, %v)", be.container.Name, objName)
 
+	var err error
+	if rd.Length() < 256*1024*1024 {
 		// wrap the reader so that net/http client cannot close the reader
-	err := be.container.GetBlobReference(objName).CreateBlockBlobFromReader(ioutil.NopCloser(rd), nil)
+		dataReader := ioutil.NopCloser(rd)
+
+		// if it's smaller than 256miB, then just create the file directly from the reader
+		err = be.container.GetBlobReference(objName).CreateBlockBlobFromReader(dataReader, nil)
+	} else {
+		// otherwise use the more complicated method
+		err = be.saveLarge(ctx, objName, rd)
+
+	}
 
 	be.sem.ReleaseToken()
 	debug.Log("%v, err %#v", objName, err)
@@ -138,6 +149,55 @@ func (be *Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindRe
 	return errors.Wrap(err, "CreateBlockBlobFromReader")
 }
 
+func (be *Backend) saveLarge(ctx context.Context, objName string, rd restic.RewindReader) error {
+	// create the file on the server
+	file := be.container.GetBlobReference(objName)
+	err := file.CreateBlockBlob(nil)
+	if err != nil {
+		return errors.Wrap(err, "CreateBlockBlob")
+	}
+
+	// read the data, in 100 MiB chunks
+	buf := make([]byte, 100*1024*1024)
+	var blocks []storage.Block
+
+	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]
+
+		// upload it as a new "block", use the base64 hash for the ID
+		h := restic.Hash(buf)
+		id := base64.StdEncoding.EncodeToString(h[:])
+		debug.Log("PutBlock %v with %d bytes", id, len(buf))
+		err = file.PutBlock(id, buf, nil)
+		if err != nil {
+			return errors.Wrap(err, "PutBlock")
+		}
+
+		blocks = append(blocks, storage.Block{
+			ID:     id,
+			Status: "Uncommitted",
+		})
+	}
+
+	debug.Log("uploaded %d parts: %v", len(blocks), blocks)
+	err = file.PutBlockList(blocks, nil)
+	debug.Log("PutBlockList returned %v", err)
+	return errors.Wrap(err, "PutBlockList")
+}
+
 // wrapReader wraps an io.ReadCloser to run an additional function on Close.
 type wrapReader struct {
 	io.ReadCloser

internal/backend/azure/azure_test.go

@@ -1,8 +1,10 @@
 package azure_test
 
 import (
+	"bytes"
 	"context"
 	"fmt"
+	"io"
 	"os"
 	"testing"
 	"time"
@@ -122,3 +124,95 @@ func BenchmarkBackendAzure(t *testing.B) {
 	t.Logf("run tests")
 	newAzureTestSuite(t).RunBenchmarks(t)
 }
+
+func TestUploadLargeFile(t *testing.T) {
+	if os.Getenv("RESTIC_AZURE_TEST_LARGE_UPLOAD") == "" {
+		t.Skip("set RESTIC_AZURE_TEST_LARGE_UPLOAD=1 to test large uploads")
+		return
+	}
+
+	ctx, cancel := context.WithCancel(context.TODO())
+	defer cancel()
+
+	if os.Getenv("RESTIC_TEST_AZURE_REPOSITORY") == "" {
+		t.Skipf("environment variables not available")
+		return
+	}
+
+	azcfg, err := azure.ParseConfig(os.Getenv("RESTIC_TEST_AZURE_REPOSITORY"))
+	if err != nil {
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	cfg := azcfg.(azure.Config)
+	cfg.AccountName = os.Getenv("RESTIC_TEST_AZURE_ACCOUNT_NAME")
+	cfg.AccountKey = os.Getenv("RESTIC_TEST_AZURE_ACCOUNT_KEY")
+	cfg.Prefix = fmt.Sprintf("test-upload-large-%d", time.Now().UnixNano())
+
+	tr, err := backend.Transport(backend.TransportOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	be, err := azure.Create(cfg, tr)
+	if err != nil {
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	defer func() {
+		err := be.Delete(ctx)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	data := rtest.Random(23, 300*1024*1024)
+	id := restic.Hash(data)
+	h := restic.Handle{Name: id.String(), Type: restic.DataFile}
+
+	t.Logf("hash of %d bytes: %v", len(data), id)
+
+	err = be.Save(ctx, h, restic.NewByteReader(data))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		err := be.Remove(ctx, h)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	var tests = []struct {
+		offset, length int
+	}{
+		{0, len(data)},
+		{23, 1024},
+		{23 + 100*1024, 500},
+		{888 + 200*1024, 89999},
+		{888 + 100*1024*1024, 120 * 1024 * 1024},
+	}
+
+	for _, test := range tests {
+		t.Run("", func(t *testing.T) {
+			want := data[test.offset : test.offset+test.length]
+
+			buf := make([]byte, test.length)
+			err = be.Load(ctx, h, test.length, int64(test.offset), func(rd io.Reader) error {
+				_, err = io.ReadFull(rd, buf)
+				return err
+			})
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if !bytes.Equal(buf, want) {
+				t.Fatalf("wrong bytes returned")
+			}
+		})
+	}
+}