implement ContentServerDataStore for azure blob storage too

pkg/azurestore/azureservice.go

@@ -21,7 +21,9 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"net/http"
 	"sort"
+	"strconv"
 	"strings"
 
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore"
@@ -67,6 +69,8 @@ type AzBlob interface {
 	Upload(ctx context.Context, body io.ReadSeeker) error
 	// Download returns a readcloser to download the contents of the blob
 	Download(ctx context.Context) (io.ReadCloser, error)
+	// Serves the contents of the blob directly handling HTTP Range requests if set
+	ServeContent(ctx context.Context, w http.ResponseWriter, r *http.Request) error
 	// Get the offset of the blob and its indexes
 	GetOffset(ctx context.Context) (int64, error)
 	// Commit the uploaded blocks to the BlockBlob
@@ -187,6 +191,31 @@ func (blockBlob *BlockBlob) Download(ctx context.Context) (io.ReadCloser, error)
 	return resp.Body, nil
 }
 
+// Serve content respecting range header
+func (blockBlob *BlockBlob) ServeContent(ctx context.Context, w http.ResponseWriter, r *http.Request) error {
+	var downloadOptions, err = parseHTTPRange(r)
+	if err != nil {
+		return err
+	}
+	resp, err := blockBlob.BlobClient.DownloadStream(ctx, downloadOptions)
+	if err != nil {
+		return err
+	}
+
+	statusCode := http.StatusOK
+	if resp.ContentRange != nil {
+		// Use 206 Partial Content for range requests
+		statusCode = http.StatusPartialContent
+	} else if resp.ContentLength != nil && *resp.ContentLength == 0 {
+		statusCode = http.StatusNoContent
+	}
+	w.WriteHeader(statusCode)
+
+	_, err = io.Copy(w, resp.Body)
+	resp.Body.Close()
+	return err
+}
+
 func (blockBlob *BlockBlob) GetOffset(ctx context.Context) (int64, error) {
 	// Get the offset of the file from azure storage
 	// For the blob, show each block (ID and size) that is a committed part of it.
@@ -253,6 +282,11 @@ func (infoBlob *InfoBlob) Download(ctx context.Context) (io.ReadCloser, error) {
 	return resp.Body, nil
 }
 
+// ServeContent is not needed for infoBlob
+func (infoBlob *InfoBlob) ServeContent(ctx context.Context, w http.ResponseWriter, r *http.Request) error {
+	return nil
+}
+
 // infoBlob does not utilise offset, so just return 0, nil
 func (infoBlob *InfoBlob) GetOffset(ctx context.Context) (int64, error) {
 	return 0, nil
@@ -309,3 +343,37 @@ func checkForNotFoundError(err error) error {
 	}
 	return err
 }
+
+// simple parse http ranging, no multipart ranges/no if-range/no last-modified, not supported by azure anyway
+func parseHTTPRange(r *http.Request) (*azblob.DownloadStreamOptions, error) {
+	rangeHeader := r.Header.Get("Range")
+	if rangeHeader == "" {
+		// this is totally fine, Range header is not required
+		return nil, nil
+	}
+
+	const prefix = "bytes="
+	if !strings.HasPrefix(rangeHeader, prefix) {
+		return nil, fmt.Errorf("invalid Range header format")
+	}
+
+	rangeParts := strings.Split(strings.TrimPrefix(rangeHeader, prefix), "-")
+	if len(rangeParts) != 2 {
+		return nil, fmt.Errorf("invalid Range header format")
+	}
+
+	offset, err := strconv.ParseInt(rangeParts[0], 10, 64)
+	if err != nil {
+		return nil, fmt.Errorf("invalid offset in Range header")
+	}
+
+	count, err := strconv.ParseInt(rangeParts[1], 10, 64)
+	if err != nil {
+		return nil, fmt.Errorf("invalid count in Range header")
+	}
+
+	downloadOptions := azblob.DownloadStreamOptions{}
+	downloadOptions.Range.Offset = offset
+	downloadOptions.Range.Count = count - offset + 1
+	return &downloadOptions, nil
+}

pkg/azurestore/azurestore.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
+	"net/http"
 	"os"
 	"strings"
 
@@ -47,6 +48,7 @@ func (store AzureStore) UseIn(composer *handler.StoreComposer) {
 	composer.UseCore(store)
 	composer.UseTerminater(store)
 	composer.UseLengthDeferrer(store)
+	composer.UseContentServer(store)
 }
 
 func (store AzureStore) NewUpload(ctx context.Context, info handler.FileInfo) (handler.Upload, error) {
@@ -149,6 +151,10 @@ func (store AzureStore) AsLengthDeclarableUpload(upload handler.Upload) handler.
 	return upload.(*AzUpload)
 }
 
+func (store AzureStore) AsServableUpload(upload handler.Upload) handler.ServableUpload {
+	return upload.(*AzUpload)
+}
+
 func (upload *AzUpload) WriteChunk(ctx context.Context, offset int64, src io.Reader) (int64, error) {
 	// Create a temporary file for holding the uploaded data
 	file, err := os.CreateTemp(upload.tempDir, "tusd-az-tmp-")
@@ -214,6 +220,10 @@ func (upload *AzUpload) GetReader(ctx context.Context) (io.ReadCloser, error) {
 	return upload.BlockBlob.Download(ctx)
 }
 
+func (upload *AzUpload) ServeContent(ctx context.Context, w http.ResponseWriter, r *http.Request) error {
+	return upload.BlockBlob.ServeContent(ctx, w, r)
+}
+
 // Finish the file upload and commit the block list
 func (upload *AzUpload) FinishUpload(ctx context.Context) error {
 	return upload.BlockBlob.Commit(ctx)