cleanup: a small Azure driver cleanup

Just so we can make the code a bit more consistent with the rest of the
storage drivers.

Signed-off-by: Milos Gajdos <milosthegajdos@gmail.com>

registry/storage/driver/azure/azure.go

@@ -18,6 +18,7 @@ import (
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore/streaming"
 	"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"
 	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/container"
 )
 
@@ -26,6 +27,8 @@ const (
 	maxChunkSize = 4 * 1024 * 1024
 )
 
+var _ storagedriver.StorageDriver = &driver{}
+
 type driver struct {
 	azClient               *azureClient
 	client                 *container.Client
@@ -34,11 +37,15 @@ type driver struct {
 	copyStatusPollDelay    time.Duration
 }
 
-type baseEmbed struct{ base.Base }
+type baseEmbed struct {
+	base.Base
+}
 
 // Driver is a storagedriver.StorageDriver implementation backed by
 // Microsoft Azure Blob Storage Service.
-type Driver struct{ baseEmbed }
+type Driver struct {
+	baseEmbed
+}
 
 func init() {
 	factory.Register(driverName, &azureDriverFactory{})
@@ -74,7 +81,12 @@ func New(params *Parameters) (*Driver, error) {
 		copyStatusPollMaxRetry: params.CopyStatusPollMaxRetry,
 		copyStatusPollDelay:    copyStatusPollDelay,
 	}
-	return &Driver{baseEmbed: baseEmbed{Base: base.Base{StorageDriver: d}}}, nil
+	return &Driver{
+		baseEmbed: baseEmbed{
+			Base: base.Base{
+				StorageDriver: d,
+			},
+		}}, nil
 }
 
 // Implement the storagedriver.StorageDriver interface.
@@ -84,25 +96,25 @@ func (d *driver) Name() string {
 
 // GetContent retrieves the content stored at "path" as a []byte.
 func (d *driver) GetContent(ctx context.Context, path string) ([]byte, error) {
-	downloadResponse, err := d.client.NewBlobClient(d.blobName(path)).DownloadStream(ctx, nil)
+	// TODO(milosgajdos): should we get a RetryReader here?
+	resp, err := d.client.NewBlobClient(d.blobName(path)).DownloadStream(ctx, nil)
 	if err != nil {
 		if is404(err) {
 			return nil, storagedriver.PathNotFoundError{Path: path}
 		}
 		return nil, err
 	}
-	body := downloadResponse.Body
+	defer resp.Body.Close()
-	defer body.Close()
+	return io.ReadAll(resp.Body)
-	return io.ReadAll(body)
 }
 
 // PutContent stores the []byte content at a location designated by "path".
 func (d *driver) PutContent(ctx context.Context, path string, contents []byte) error {
+	// TODO(milosgajdos): this check is not needed as UploadBuffer will return error if we exceed the max blockbytes limit
 	// max size for block blobs uploaded via single "Put Blob" for version after "2016-05-31"
 	// https://docs.microsoft.com/en-us/rest/api/storageservices/put-blob#remarks
-	const limit = 256 * 1024 * 1024
+	if len(contents) > blockblob.MaxUploadBlobBytes {
-	if len(contents) > limit {
+		return fmt.Errorf("content size exceeds max allowed limit (%d): %d", blockblob.MaxUploadBlobBytes, len(contents))
-		return fmt.Errorf("uploading %d bytes with PutContent is not supported; limit: %d bytes", len(contents), limit)
 	}
 
 	// Historically, blobs uploaded via PutContent used to be of type AppendBlob
@@ -128,6 +140,7 @@ func (d *driver) PutContent(ctx context.Context, path string, contents []byte) e
 		}
 	}
 
+	// TODO(milosgajdos): should we set some concurrency options on UploadBuffer
 	_, err = d.client.NewBlockBlobClient(blobName).UploadBuffer(ctx, contents, nil)
 	return err
 }
@@ -149,13 +162,14 @@ func (d *driver) Reader(ctx context.Context, path string, offset int64) (io.Read
 		return nil, fmt.Errorf("failed to get blob properties: %v", err)
 	}
 	if props.ContentLength == nil {
-		return nil, fmt.Errorf("failed to get ContentLength for path: %s", path)
+		return nil, fmt.Errorf("missing ContentLength: %s", path)
 	}
 	size := *props.ContentLength
 	if offset >= size {
 		return io.NopCloser(bytes.NewReader(nil)), nil
 	}
 
+	// TODO(milosgajdos): should we get a RetryReader here?
 	resp, err := blobRef.DownloadStream(ctx, &options)
 	if err != nil {
 		if is404(err) {
@@ -168,7 +182,7 @@ func (d *driver) Reader(ctx context.Context, path string, offset int64) (io.Read
 
 // Writer returns a FileWriter which will store the content written to it
 // at the location designated by "path" after the call to Commit.
-func (d *driver) Writer(ctx context.Context, path string, append bool) (storagedriver.FileWriter, error) {
+func (d *driver) Writer(ctx context.Context, path string, appendMode bool) (storagedriver.FileWriter, error) {
 	blobName := d.blobName(path)
 	blobRef := d.client.NewBlobClient(blobName)
 
@@ -183,9 +197,9 @@ func (d *driver) Writer(ctx context.Context, path string, append bool) (storaged
 
 	var size int64
 	if blobExists {
-		if append {
+		if appendMode {
 			if props.ContentLength == nil {
-				return nil, fmt.Errorf("cannot append to blob because no ContentLength property was returned for: %s", blobName)
+				return nil, fmt.Errorf("missing ContentLength: %s", blobName)
 			}
 			size = *props.ContentLength
 		} else {
@@ -194,7 +208,7 @@ func (d *driver) Writer(ctx context.Context, path string, append bool) (storaged
 			}
 		}
 	} else {
-		if append {
+		if appendMode {
 			return nil, storagedriver.PathNotFoundError{Path: path}
 		}
 		if _, err = d.client.NewAppendBlobClient(blobName).Create(ctx, nil); err != nil {
@@ -225,9 +239,10 @@ func (d *driver) Stat(ctx context.Context, path string) (storagedriver.FileInfo,
 		}
 
 		if len(missing) > 0 {
-			return nil, fmt.Errorf("required blob properties %s are missing for blob: %s", missing, blobName)
+			return nil, fmt.Errorf("missing required prroperties (%s) for blob: %s", missing, blobName)
 		}
-		return storagedriver.FileInfoInternal{FileInfoFields: storagedriver.FileInfoFields{
+		return storagedriver.FileInfoInternal{
+			FileInfoFields: storagedriver.FileInfoFields{
 				Path:    path,
 				Size:    *props.ContentLength,
 				ModTime: *props.LastModified,
@@ -253,7 +268,8 @@ func (d *driver) Stat(ctx context.Context, path string) (storagedriver.FileInfo,
 		}
 		if len(resp.Segment.BlobItems) > 0 {
 			// path is a virtual container
-			return storagedriver.FileInfoInternal{FileInfoFields: storagedriver.FileInfoFields{
+			return storagedriver.FileInfoInternal{
+				FileInfoFields: storagedriver.FileInfoFields{
 					Path:  path,
 					IsDir: true,
 				}}, nil
@@ -452,10 +468,9 @@ func (d *driver) listBlobs(ctx context.Context, virtPath string) ([]string, erro
 		}
 		for _, blob := range resp.Segment.BlobItems {
 			if blob.Name == nil {
-				return nil, fmt.Errorf("required blob property Name is missing while listing blobs under: %s", listPrefix)
+				return nil, fmt.Errorf("missing blob Name when listing prefix: %s", listPrefix)
 			}
-			name := *blob.Name
+			out = append(out, strings.Replace(*blob.Name, blobPrefix, prefix, 1))
-			out = append(out, strings.Replace(name, blobPrefix, prefix, 1))
 		}
 	}
 
@@ -473,6 +488,7 @@ func (d *driver) blobName(path string) string {
 	return strings.TrimLeft(strings.TrimRight(d.rootDirectory, "/")+path, "/")
 }
 
+// TODO(milosgajdos): consider renaming this func
 func is404(err error) bool {
 	return bloberror.HasCode(
 		err,
@@ -483,6 +499,8 @@ func is404(err error) bool {
 	)
 }
 
+var _ storagedriver.FileWriter = &writer{}
+
 type writer struct {
 	driver    *driver
 	path      string
@@ -498,6 +516,7 @@ func (d *driver) newWriter(ctx context.Context, path string, size int64) storage
 		driver: d,
 		path:   path,
 		size:   size,
+		// TODO(milosgajdos): I'm not sure about the maxChunkSize
 		bw: bufio.NewWriterSize(&blockWriter{
 			ctx:    ctx,
 			client: d.client,