Add support for Azure package pools

This adds support for storing packages directly on Azure, with no truly
"local" (on-disk) repo used. The existing Azure PublishedStorage
implementation was refactored to move the shared code to a separate
context struct, which can then be re-used by the new PackagePool. In
addition, the files package's mockChecksumStorage was made public so
that it could be used in the Azure PackagePool tests as well.

Signed-off-by: Ryan Gonzalez <ryan.gonzalez@collabora.com>

azure/azure.go

@@ -1,2 +1,128 @@
 // Package azure handles publishing to Azure Storage
 package azure
+
+import (
+	"context"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"net/url"
+	"path/filepath"
+	"time"
+
+	"github.com/Azure/azure-storage-blob-go/azblob"
+	"github.com/aptly-dev/aptly/aptly"
+)
+
+func isBlobNotFound(err error) bool {
+	storageError, ok := err.(azblob.StorageError)
+	return ok && storageError.ServiceCode() == azblob.ServiceCodeBlobNotFound
+}
+
+type azContext struct {
+	container azblob.ContainerURL
+	prefix    string
+}
+
+func newAzContext(accountName, accountKey, container, prefix, endpoint string) (*azContext, error) {
+	credential, err := azblob.NewSharedKeyCredential(accountName, accountKey)
+	if err != nil {
+		return nil, err
+	}
+
+	if endpoint == "" {
+		endpoint = fmt.Sprintf("https://%s.blob.core.windows.net", accountName)
+	}
+
+	url, err := url.Parse(fmt.Sprintf("%s/%s", endpoint, container))
+	if err != nil {
+		return nil, err
+	}
+
+	containerURL := azblob.NewContainerURL(*url, azblob.NewPipeline(credential, azblob.PipelineOptions{}))
+
+	result := &azContext{
+		container: containerURL,
+		prefix:    prefix,
+	}
+
+	return result, nil
+}
+
+func (az *azContext) blobPath(path string) string {
+	return filepath.Join(az.prefix, path)
+}
+
+func (az *azContext) blobURL(path string) azblob.BlobURL {
+	return az.container.NewBlobURL(az.blobPath(path))
+}
+
+func (az *azContext) internalFilelist(prefix string, progress aptly.Progress) (paths []string, md5s []string, err error) {
+	const delimiter = "/"
+	paths = make([]string, 0, 1024)
+	md5s = make([]string, 0, 1024)
+	prefix = filepath.Join(az.prefix, prefix)
+	if prefix != "" {
+		prefix += delimiter
+	}
+
+	for marker := (azblob.Marker{}); marker.NotDone(); {
+		listBlob, err := az.container.ListBlobsFlatSegment(
+			context.Background(), marker, azblob.ListBlobsSegmentOptions{
+				Prefix:     prefix,
+				MaxResults: 1,
+				Details:    azblob.BlobListingDetails{Metadata: true}})
+		if err != nil {
+			return nil, nil, fmt.Errorf("error listing under prefix %s in %s: %s", prefix, az, err)
+		}
+
+		marker = listBlob.NextMarker
+
+		for _, blob := range listBlob.Segment.BlobItems {
+			if prefix == "" {
+				paths = append(paths, blob.Name)
+			} else {
+				paths = append(paths, blob.Name[len(prefix):])
+			}
+			md5s = append(md5s, fmt.Sprintf("%x", blob.Properties.ContentMD5))
+		}
+
+		if progress != nil {
+			time.Sleep(time.Duration(500) * time.Millisecond)
+			progress.AddBar(1)
+		}
+	}
+
+	return paths, md5s, nil
+}
+
+func (az *azContext) putFile(blob azblob.BlobURL, source io.Reader, sourceMD5 string) error {
+	uploadOptions := azblob.UploadStreamToBlockBlobOptions{
+		BufferSize: 4 * 1024 * 1024,
+		MaxBuffers: 8,
+	}
+
+	if len(sourceMD5) > 0 {
+		decodedMD5, err := hex.DecodeString(sourceMD5)
+		if err != nil {
+			return err
+		}
+		uploadOptions.BlobHTTPHeaders = azblob.BlobHTTPHeaders{
+			ContentMD5: decodedMD5,
+		}
+	}
+
+	_, err := azblob.UploadStreamToBlockBlob(
+		context.Background(),
+		source,
+		blob.ToBlockBlobURL(),
+		uploadOptions,
+	)
+
+	return err
+}
+
+// String
+func (az *azContext) String() string {
+	return fmt.Sprintf("Azure: %s/%s", az.container, az.prefix)
+}