X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/908261de15c98553a4200f01aff1f26ef57c8fb8..93cfe7c262708fb09eda5aad1839c832816d4591:/services/keepstore/azure_blob_volume.go

diff --git a/services/keepstore/azure_blob_volume.go b/services/keepstore/azure_blob_volume.go
index c0033d9186..3c17b3bd06 100644
--- a/services/keepstore/azure_blob_volume.go
+++ b/services/keepstore/azure_blob_volume.go
@@ -1,20 +1,35 @@
+// Copyright (C) The Arvados Authors. All rights reserved.
+//
+// SPDX-License-Identifier: AGPL-3.0
+
 package main
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"flag"
 	"fmt"
 	"io"
 	"io/ioutil"
-	"log"
+	"net/http"
 	"os"
 	"regexp"
+	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
-	"github.com/curoverse/azure-sdk-for-go/storage"
+	"git.curoverse.com/arvados.git/sdk/go/arvados"
+	"github.com/Azure/azure-sdk-for-go/storage"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const (
+	azureDefaultRequestTimeout       = arvados.Duration(10 * time.Minute)
+	azureDefaultListBlobsMaxAttempts = 12
+	azureDefaultListBlobsRetryDelay  = arvados.Duration(10 * time.Second)
 )
 
 var (
@@ -39,37 +54,29 @@ func readKeyFromFile(file string) (string, error) {
 }
 
 type azureVolumeAdder struct {
-	*volumeSet
+	*Config
+}
+
+// String implements flag.Value
+func (s *azureVolumeAdder) String() string {
+	return "-"
 }
 
 func (s *azureVolumeAdder) Set(containerName string) error {
-	if containerName == "" {
-		return errors.New("no container name given")
-	}
-	if azureStorageAccountName == "" || azureStorageAccountKeyFile == "" {
-		return errors.New("-azure-storage-account-name and -azure-storage-account-key-file arguments must given before -azure-storage-container-volume")
-	}
-	accountKey, err := readKeyFromFile(azureStorageAccountKeyFile)
-	if err != nil {
-		return err
-	}
-	azClient, err := storage.NewBasicClient(azureStorageAccountName, accountKey)
-	if err != nil {
-		return errors.New("creating Azure storage client: " + err.Error())
-	}
-	if flagSerializeIO {
-		log.Print("Notice: -serialize is not supported by azure-blob-container volumes.")
-	}
-	v := NewAzureBlobVolume(azClient, containerName, flagReadonly, azureStorageReplication)
-	if err := v.Check(); err != nil {
-		return err
-	}
-	*s.volumeSet = append(*s.volumeSet, v)
+	s.Config.Volumes = append(s.Config.Volumes, &AzureBlobVolume{
+		ContainerName:         containerName,
+		StorageAccountName:    azureStorageAccountName,
+		StorageAccountKeyFile: azureStorageAccountKeyFile,
+		AzureReplication:      azureStorageReplication,
+		ReadOnly:              deprecated.flagReadonly,
+	})
 	return nil
 }
 
 func init() {
-	flag.Var(&azureVolumeAdder{&volumes},
+	VolumeTypes = append(VolumeTypes, func() VolumeWithExamples { return &AzureBlobVolume{} })
+
+	flag.Var(&azureVolumeAdder{theConfig},
 		"azure-storage-container-volume",
 		"Use the given container as a storage volume. Can be given multiple times.")
 	flag.StringVar(
@@ -81,7 +88,7 @@ func init() {
 		&azureStorageAccountKeyFile,
 		"azure-storage-account-key-file",
 		"",
-		"File containing the account key used for subsequent --azure-storage-container-volume arguments.")
+		"`File` containing the account key used for subsequent --azure-storage-container-volume arguments.")
 	flag.IntVar(
 		&azureStorageReplication,
 		"azure-storage-replication",
@@ -97,49 +104,140 @@ func init() {
 // An AzureBlobVolume stores and retrieves blocks in an Azure Blob
 // container.
 type AzureBlobVolume struct {
-	azClient      storage.Client
-	bsClient      storage.BlobStorageClient
-	containerName string
-	readonly      bool
-	replication   int
+	StorageAccountName    string
+	StorageAccountKeyFile string
+	StorageBaseURL        string // "" means default, "core.windows.net"
+	ContainerName         string
+	AzureReplication      int
+	ReadOnly              bool
+	RequestTimeout        arvados.Duration
+	StorageClasses        []string
+	ListBlobsRetryDelay   arvados.Duration
+	ListBlobsMaxAttempts  int
+
+	azClient  storage.Client
+	container *azureContainer
+}
+
+// singleSender is a single-attempt storage.Sender.
+type singleSender struct{}
+
+// Send performs req exactly once.
+func (*singleSender) Send(c *storage.Client, req *http.Request) (resp *http.Response, err error) {
+	return c.HTTPClient.Do(req)
 }
 
-// NewAzureBlobVolume returns a new AzureBlobVolume using the given
-// client and container name. The replication argument specifies the
-// replication level to report when writing data.
-func NewAzureBlobVolume(client storage.Client, containerName string, readonly bool, replication int) *AzureBlobVolume {
-	return &AzureBlobVolume{
-		azClient:      client,
-		bsClient:      client.GetBlobService(),
-		containerName: containerName,
-		readonly:      readonly,
-		replication:   replication,
+// Examples implements VolumeWithExamples.
+func (*AzureBlobVolume) Examples() []Volume {
+	return []Volume{
+		&AzureBlobVolume{
+			StorageAccountName:    "example-account-name",
+			StorageAccountKeyFile: "/etc/azure_storage_account_key.txt",
+			ContainerName:         "example-container-name",
+			AzureReplication:      3,
+			RequestTimeout:        azureDefaultRequestTimeout,
+		},
+		&AzureBlobVolume{
+			StorageAccountName:    "cn-account-name",
+			StorageAccountKeyFile: "/etc/azure_cn_storage_account_key.txt",
+			StorageBaseURL:        "core.chinacloudapi.cn",
+			ContainerName:         "cn-container-name",
+			AzureReplication:      3,
+			RequestTimeout:        azureDefaultRequestTimeout,
+		},
 	}
 }
 
-// Check returns nil if the volume is usable.
-func (v *AzureBlobVolume) Check() error {
-	ok, err := v.bsClient.ContainerExists(v.containerName)
+// Type implements Volume.
+func (v *AzureBlobVolume) Type() string {
+	return "Azure"
+}
+
+// Start implements Volume.
+func (v *AzureBlobVolume) Start(vm *volumeMetricsVecs) error {
+	if v.ListBlobsRetryDelay == 0 {
+		v.ListBlobsRetryDelay = azureDefaultListBlobsRetryDelay
+	}
+	if v.ListBlobsMaxAttempts == 0 {
+		v.ListBlobsMaxAttempts = azureDefaultListBlobsMaxAttempts
+	}
+	if v.ContainerName == "" {
+		return errors.New("no container name given")
+	}
+	if v.StorageAccountName == "" || v.StorageAccountKeyFile == "" {
+		return errors.New("StorageAccountName and StorageAccountKeyFile must be given")
+	}
+	accountKey, err := readKeyFromFile(v.StorageAccountKeyFile)
 	if err != nil {
 		return err
 	}
-	if !ok {
-		return errors.New("container does not exist")
+	if v.StorageBaseURL == "" {
+		v.StorageBaseURL = storage.DefaultBaseURL
+	}
+	v.azClient, err = storage.NewClient(v.StorageAccountName, accountKey, v.StorageBaseURL, storage.DefaultAPIVersion, true)
+	if err != nil {
+		return fmt.Errorf("creating Azure storage client: %s", err)
 	}
+	v.azClient.Sender = &singleSender{}
+
+	if v.RequestTimeout == 0 {
+		v.RequestTimeout = azureDefaultRequestTimeout
+	}
+	v.azClient.HTTPClient = &http.Client{
+		Timeout: time.Duration(v.RequestTimeout),
+	}
+	bs := v.azClient.GetBlobService()
+	v.container = &azureContainer{
+		ctr: bs.GetContainerReference(v.ContainerName),
+	}
+
+	if ok, err := v.container.Exists(); err != nil {
+		return err
+	} else if !ok {
+		return fmt.Errorf("Azure container %q does not exist", v.ContainerName)
+	}
+	// Set up prometheus metrics
+	lbls := prometheus.Labels{"device_id": v.DeviceID()}
+	v.container.stats.opsCounters, v.container.stats.errCounters, v.container.stats.ioBytes = vm.getCounterVecsFor(lbls)
+
 	return nil
 }
 
+// DeviceID returns a globally unique ID for the storage container.
+func (v *AzureBlobVolume) DeviceID() string {
+	return "azure://" + v.StorageBaseURL + "/" + v.StorageAccountName + "/" + v.ContainerName
+}
+
+// Return true if expires_at metadata attribute is found on the block
+func (v *AzureBlobVolume) checkTrashed(loc string) (bool, map[string]string, error) {
+	metadata, err := v.container.GetBlobMetadata(loc)
+	if err != nil {
+		return false, metadata, v.translateError(err)
+	}
+	if metadata["expires_at"] != "" {
+		return true, metadata, nil
+	}
+	return false, metadata, nil
+}
+
 // Get reads a Keep block that has been stored as a block blob in the
 // container.
 //
 // If the block is younger than azureWriteRaceInterval and is
 // unexpectedly empty, assume a PutBlob operation is in progress, and
 // wait for it to finish writing.
-func (v *AzureBlobVolume) Get(loc string) ([]byte, error) {
+func (v *AzureBlobVolume) Get(ctx context.Context, loc string, buf []byte) (int, error) {
+	trashed, _, err := v.checkTrashed(loc)
+	if err != nil {
+		return 0, err
+	}
+	if trashed {
+		return 0, os.ErrNotExist
+	}
 	var deadline time.Time
 	haveDeadline := false
-	buf, err := v.get(loc)
-	for err == nil && len(buf) == 0 && loc != "d41d8cd98f00b204e9800998ecf8427e" {
+	size, err := v.get(ctx, loc, buf)
+	for err == nil && size == 0 && loc != "d41d8cd98f00b204e9800998ecf8427e" {
 		// Seeing a brand new empty block probably means we're
 		// in a race with CreateBlob, which under the hood
 		// (apparently) does "CreateEmpty" and "CommitData"
@@ -159,43 +257,55 @@ func (v *AzureBlobVolume) Get(loc string) ([]byte, error) {
 		} else if time.Now().After(deadline) {
 			break
 		}
-		bufs.Put(buf)
-		time.Sleep(azureWriteRacePollTime)
-		buf, err = v.get(loc)
+		select {
+		case <-ctx.Done():
+			return 0, ctx.Err()
+		case <-time.After(azureWriteRacePollTime):
+		}
+		size, err = v.get(ctx, loc, buf)
 	}
 	if haveDeadline {
-		log.Printf("Race ended with len(buf)==%d", len(buf))
+		log.Printf("Race ended with size==%d", size)
 	}
-	return buf, err
+	return size, err
 }
 
-func (v *AzureBlobVolume) get(loc string) ([]byte, error) {
-	expectSize := BlockSize
+func (v *AzureBlobVolume) get(ctx context.Context, loc string, buf []byte) (int, error) {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+	expectSize := len(buf)
 	if azureMaxGetBytes < BlockSize {
 		// Unfortunately the handler doesn't tell us how long the blob
 		// is expected to be, so we have to ask Azure.
-		props, err := v.bsClient.GetBlobProperties(v.containerName, loc)
+		props, err := v.container.GetBlobProperties(loc)
 		if err != nil {
-			return nil, v.translateError(err)
+			return 0, v.translateError(err)
 		}
 		if props.ContentLength > int64(BlockSize) || props.ContentLength < 0 {
-			return nil, fmt.Errorf("block %s invalid size %d (max %d)", loc, props.ContentLength, BlockSize)
+			return 0, fmt.Errorf("block %s invalid size %d (max %d)", loc, props.ContentLength, BlockSize)
 		}
 		expectSize = int(props.ContentLength)
 	}
 
-	buf := bufs.Get(expectSize)
 	if expectSize == 0 {
-		return buf, nil
+		return 0, nil
 	}
 
 	// We'll update this actualSize if/when we get the last piece.
 	actualSize := -1
 	pieces := (expectSize + azureMaxGetBytes - 1) / azureMaxGetBytes
-	errors := make([]error, pieces)
+	errors := make(chan error, pieces)
 	var wg sync.WaitGroup
 	wg.Add(pieces)
 	for p := 0; p < pieces; p++ {
+		// Each goroutine retrieves one piece. If we hit an
+		// error, it is sent to the errors chan so get() can
+		// return it -- but only if the error happens before
+		// ctx is done. This way, if ctx is done before we hit
+		// any other error (e.g., requesting client has hung
+		// up), we return the original ctx.Err() instead of
+		// the secondary errors from the transfers that got
+		// interrupted as a result.
 		go func(p int) {
 			defer wg.Done()
 			startPos := p * azureMaxGetBytes
@@ -205,23 +315,51 @@ func (v *AzureBlobVolume) get(loc string) ([]byte, error) {
 			}
 			var rdr io.ReadCloser
 			var err error
-			if startPos == 0 && endPos == expectSize {
-				rdr, err = v.bsClient.GetBlob(v.containerName, loc)
-			} else {
-				rdr, err = v.bsClient.GetBlobRange(v.containerName, loc, fmt.Sprintf("%d-%d", startPos, endPos-1))
+			gotRdr := make(chan struct{})
+			go func() {
+				defer close(gotRdr)
+				if startPos == 0 && endPos == expectSize {
+					rdr, err = v.container.GetBlob(loc)
+				} else {
+					rdr, err = v.container.GetBlobRange(loc, startPos, endPos-1, nil)
+				}
+			}()
+			select {
+			case <-ctx.Done():
+				go func() {
+					<-gotRdr
+					if err == nil {
+						rdr.Close()
+					}
+				}()
+				return
+			case <-gotRdr:
 			}
 			if err != nil {
-				errors[p] = err
+				errors <- err
+				cancel()
 				return
 			}
-			defer rdr.Close()
+			go func() {
+				// Close the reader when the client
+				// hangs up or another piece fails
+				// (possibly interrupting ReadFull())
+				// or when all pieces succeed and
+				// get() returns.
+				<-ctx.Done()
+				rdr.Close()
+			}()
 			n, err := io.ReadFull(rdr, buf[startPos:endPos])
 			if pieces == 1 && (err == io.ErrUnexpectedEOF || err == io.EOF) {
 				// If we don't know the actual size,
 				// and just tried reading 64 MiB, it's
 				// normal to encounter EOF.
 			} else if err != nil {
-				errors[p] = err
+				if ctx.Err() == nil {
+					errors <- err
+				}
+				cancel()
+				return
 			}
 			if p == pieces-1 {
 				actualSize = startPos + n
@@ -229,72 +367,148 @@ func (v *AzureBlobVolume) get(loc string) ([]byte, error) {
 		}(p)
 	}
 	wg.Wait()
-	for _, err := range errors {
-		if err != nil {
-			bufs.Put(buf)
-			return nil, v.translateError(err)
-		}
+	close(errors)
+	if len(errors) > 0 {
+		return 0, v.translateError(<-errors)
+	}
+	if ctx.Err() != nil {
+		return 0, ctx.Err()
 	}
-	return buf[:actualSize], nil
+	return actualSize, nil
 }
 
 // Compare the given data with existing stored data.
-func (v *AzureBlobVolume) Compare(loc string, expect []byte) error {
-	rdr, err := v.bsClient.GetBlob(v.containerName, loc)
+func (v *AzureBlobVolume) Compare(ctx context.Context, loc string, expect []byte) error {
+	trashed, _, err := v.checkTrashed(loc)
+	if err != nil {
+		return err
+	}
+	if trashed {
+		return os.ErrNotExist
+	}
+	var rdr io.ReadCloser
+	gotRdr := make(chan struct{})
+	go func() {
+		defer close(gotRdr)
+		rdr, err = v.container.GetBlob(loc)
+	}()
+	select {
+	case <-ctx.Done():
+		go func() {
+			<-gotRdr
+			if err == nil {
+				rdr.Close()
+			}
+		}()
+		return ctx.Err()
+	case <-gotRdr:
+	}
 	if err != nil {
 		return v.translateError(err)
 	}
 	defer rdr.Close()
-	return compareReaderWithBuf(rdr, expect, loc[:32])
+	return compareReaderWithBuf(ctx, rdr, expect, loc[:32])
 }
 
 // Put stores a Keep block as a block blob in the container.
-func (v *AzureBlobVolume) Put(loc string, block []byte) error {
-	if v.readonly {
+func (v *AzureBlobVolume) Put(ctx context.Context, loc string, block []byte) error {
+	if v.ReadOnly {
 		return MethodDisabledError
 	}
-	return v.bsClient.CreateBlockBlobFromReader(v.containerName, loc, uint64(len(block)), bytes.NewReader(block))
+	// Send the block data through a pipe, so that (if we need to)
+	// we can close the pipe early and abandon our
+	// CreateBlockBlobFromReader() goroutine, without worrying
+	// about CreateBlockBlobFromReader() accessing our block
+	// buffer after we release it.
+	bufr, bufw := io.Pipe()
+	go func() {
+		io.Copy(bufw, bytes.NewReader(block))
+		bufw.Close()
+	}()
+	errChan := make(chan error)
+	go func() {
+		var body io.Reader = bufr
+		if len(block) == 0 {
+			// We must send a "Content-Length: 0" header,
+			// but the http client interprets
+			// ContentLength==0 as "unknown" unless it can
+			// confirm by introspection that Body will
+			// read 0 bytes.
+			body = http.NoBody
+			bufr.Close()
+		}
+		errChan <- v.container.CreateBlockBlobFromReader(loc, len(block), body, nil)
+	}()
+	select {
+	case <-ctx.Done():
+		theConfig.debugLogf("%s: taking CreateBlockBlobFromReader's input away: %s", v, ctx.Err())
+		// Our pipe might be stuck in Write(), waiting for
+		// io.Copy() to read. If so, un-stick it. This means
+		// CreateBlockBlobFromReader will get corrupt data,
+		// but that's OK: the size won't match, so the write
+		// will fail.
+		go io.Copy(ioutil.Discard, bufr)
+		// CloseWithError() will return once pending I/O is done.
+		bufw.CloseWithError(ctx.Err())
+		theConfig.debugLogf("%s: abandoning CreateBlockBlobFromReader goroutine", v)
+		return ctx.Err()
+	case err := <-errChan:
+		return err
+	}
 }
 
 // Touch updates the last-modified property of a block blob.
 func (v *AzureBlobVolume) Touch(loc string) error {
-	if v.readonly {
+	if v.ReadOnly {
 		return MethodDisabledError
 	}
-	return v.bsClient.SetBlobMetadata(v.containerName, loc, map[string]string{
-		"touch": fmt.Sprintf("%d", time.Now()),
-	})
+	trashed, metadata, err := v.checkTrashed(loc)
+	if err != nil {
+		return err
+	}
+	if trashed {
+		return os.ErrNotExist
+	}
+
+	metadata["touch"] = fmt.Sprintf("%d", time.Now().Unix())
+	return v.container.SetBlobMetadata(loc, metadata, nil)
 }
 
 // Mtime returns the last-modified property of a block blob.
 func (v *AzureBlobVolume) Mtime(loc string) (time.Time, error) {
-	props, err := v.bsClient.GetBlobProperties(v.containerName, loc)
+	trashed, _, err := v.checkTrashed(loc)
 	if err != nil {
 		return time.Time{}, err
 	}
-	return time.Parse(time.RFC1123, props.LastModified)
+	if trashed {
+		return time.Time{}, os.ErrNotExist
+	}
+
+	props, err := v.container.GetBlobProperties(loc)
+	if err != nil {
+		return time.Time{}, err
+	}
+	return time.Time(props.LastModified), nil
 }
 
 // IndexTo writes a list of Keep blocks that are stored in the
 // container.
 func (v *AzureBlobVolume) IndexTo(prefix string, writer io.Writer) error {
 	params := storage.ListBlobsParameters{
-		Prefix: prefix,
+		Prefix:  prefix,
+		Include: &storage.IncludeBlobDataset{Metadata: true},
 	}
-	for {
-		resp, err := v.bsClient.ListBlobs(v.containerName, params)
+	for page := 1; ; page++ {
+		resp, err := v.listBlobs(page, params)
 		if err != nil {
 			return err
 		}
 		for _, b := range resp.Blobs {
-			t, err := time.Parse(time.RFC1123, b.Properties.LastModified)
-			if err != nil {
-				return err
-			}
 			if !v.isKeepBlock(b.Name) {
 				continue
 			}
-			if b.Properties.ContentLength == 0 && t.Add(azureWriteRaceInterval).After(time.Now()) {
+			modtime := time.Time(b.Properties.LastModified)
+			if b.Properties.ContentLength == 0 && modtime.Add(azureWriteRaceInterval).After(time.Now()) {
 				// A new zero-length blob is probably
 				// just a new non-empty blob that
 				// hasn't committed its data yet (see
@@ -302,7 +516,11 @@ func (v *AzureBlobVolume) IndexTo(prefix string, writer io.Writer) error {
 				// value.
 				continue
 			}
-			fmt.Fprintf(writer, "%s+%d %d\n", b.Name, b.Properties.ContentLength, t.Unix())
+			if b.Metadata["expires_at"] != "" {
+				// Trashed blob; exclude it from response
+				continue
+			}
+			fmt.Fprintf(writer, "%s+%d %d\n", b.Name, b.Properties.ContentLength, modtime.UnixNano())
 		}
 		if resp.NextMarker == "" {
 			return nil
@@ -311,30 +529,76 @@ func (v *AzureBlobVolume) IndexTo(prefix string, writer io.Writer) error {
 	}
 }
 
-// Delete a Keep block.
-func (v *AzureBlobVolume) Delete(loc string) error {
-	if v.readonly {
+// call v.container.ListBlobs, retrying if needed.
+func (v *AzureBlobVolume) listBlobs(page int, params storage.ListBlobsParameters) (resp storage.BlobListResponse, err error) {
+	for i := 0; i < v.ListBlobsMaxAttempts; i++ {
+		resp, err = v.container.ListBlobs(params)
+		err = v.translateError(err)
+		if err == VolumeBusyError {
+			log.Printf("ListBlobs: will retry page %d in %s after error: %s", page, v.ListBlobsRetryDelay, err)
+			time.Sleep(time.Duration(v.ListBlobsRetryDelay))
+			continue
+		} else {
+			break
+		}
+	}
+	return
+}
+
+// Trash a Keep block.
+func (v *AzureBlobVolume) Trash(loc string) error {
+	if v.ReadOnly {
 		return MethodDisabledError
 	}
+
 	// Ideally we would use If-Unmodified-Since, but that
 	// particular condition seems to be ignored by Azure. Instead,
 	// we get the Etag before checking Mtime, and use If-Match to
 	// ensure we don't delete data if Put() or Touch() happens
 	// between our calls to Mtime() and DeleteBlob().
-	props, err := v.bsClient.GetBlobProperties(v.containerName, loc)
+	props, err := v.container.GetBlobProperties(loc)
 	if err != nil {
 		return err
 	}
 	if t, err := v.Mtime(loc); err != nil {
 		return err
-	} else if time.Since(t) < blobSignatureTTL {
+	} else if time.Since(t) < theConfig.BlobSignatureTTL.Duration() {
 		return nil
 	}
-	return v.bsClient.DeleteBlob(v.containerName, loc, map[string]string{
-		"If-Match": props.Etag,
+
+	// If TrashLifetime == 0, just delete it
+	if theConfig.TrashLifetime == 0 {
+		return v.container.DeleteBlob(loc, &storage.DeleteBlobOptions{
+			IfMatch: props.Etag,
+		})
+	}
+
+	// Otherwise, mark as trash
+	return v.container.SetBlobMetadata(loc, storage.BlobMetadata{
+		"expires_at": fmt.Sprintf("%d", time.Now().Add(theConfig.TrashLifetime.Duration()).Unix()),
+	}, &storage.SetBlobMetadataOptions{
+		IfMatch: props.Etag,
 	})
 }
 
+// Untrash a Keep block.
+// Delete the expires_at metadata attribute
+func (v *AzureBlobVolume) Untrash(loc string) error {
+	// if expires_at does not exist, return NotFoundError
+	metadata, err := v.container.GetBlobMetadata(loc)
+	if err != nil {
+		return v.translateError(err)
+	}
+	if metadata["expires_at"] == "" {
+		return os.ErrNotExist
+	}
+
+	// reset expires_at metadata attribute
+	metadata["expires_at"] = ""
+	err = v.container.SetBlobMetadata(loc, metadata, nil)
+	return v.translateError(err)
+}
+
 // Status returns a VolumeStatus struct with placeholder data.
 func (v *AzureBlobVolume) Status() *VolumeStatus {
 	return &VolumeStatus{
@@ -346,19 +610,24 @@ func (v *AzureBlobVolume) Status() *VolumeStatus {
 
 // String returns a volume label, including the container name.
 func (v *AzureBlobVolume) String() string {
-	return fmt.Sprintf("azure-storage-container:%+q", v.containerName)
+	return fmt.Sprintf("azure-storage-container:%+q", v.ContainerName)
 }
 
 // Writable returns true, unless the -readonly flag was on when the
 // volume was added.
 func (v *AzureBlobVolume) Writable() bool {
-	return !v.readonly
+	return !v.ReadOnly
 }
 
 // Replication returns the replication level of the container, as
 // specified by the -azure-storage-replication argument.
 func (v *AzureBlobVolume) Replication() int {
-	return v.replication
+	return v.AzureReplication
+}
+
+// GetStorageClasses implements Volume
+func (v *AzureBlobVolume) GetStorageClasses() []string {
+	return v.StorageClasses
 }
 
 // If possible, translate an Azure SDK error to a recognizable error
@@ -367,7 +636,10 @@ func (v *AzureBlobVolume) translateError(err error) error {
 	switch {
 	case err == nil:
 		return err
-	case strings.Contains(err.Error(), "404 Not Found"):
+	case strings.Contains(err.Error(), "StatusCode=503"):
+		// "storage: service returned error: StatusCode=503, ErrorCode=ServerBusy, ErrorMessage=The server is busy" (See #14804)
+		return VolumeBusyError
+	case strings.Contains(err.Error(), "Not Found"):
 		// "storage: service returned without a response body (404 Not Found)"
 		return os.ErrNotExist
 	default:
@@ -380,3 +652,214 @@ var keepBlockRegexp = regexp.MustCompile(`^[0-9a-f]{32}$`)
 func (v *AzureBlobVolume) isKeepBlock(s string) bool {
 	return keepBlockRegexp.MatchString(s)
 }
+
+// EmptyTrash looks for trashed blocks that exceeded TrashLifetime
+// and deletes them from the volume.
+func (v *AzureBlobVolume) EmptyTrash() {
+	var bytesDeleted, bytesInTrash int64
+	var blocksDeleted, blocksInTrash int64
+
+	doBlob := func(b storage.Blob) {
+		// Check whether the block is flagged as trash
+		if b.Metadata["expires_at"] == "" {
+			return
+		}
+
+		atomic.AddInt64(&blocksInTrash, 1)
+		atomic.AddInt64(&bytesInTrash, b.Properties.ContentLength)
+
+		expiresAt, err := strconv.ParseInt(b.Metadata["expires_at"], 10, 64)
+		if err != nil {
+			log.Printf("EmptyTrash: ParseInt(%v): %v", b.Metadata["expires_at"], err)
+			return
+		}
+
+		if expiresAt > time.Now().Unix() {
+			return
+		}
+
+		err = v.container.DeleteBlob(b.Name, &storage.DeleteBlobOptions{
+			IfMatch: b.Properties.Etag,
+		})
+		if err != nil {
+			log.Printf("EmptyTrash: DeleteBlob(%v): %v", b.Name, err)
+			return
+		}
+		atomic.AddInt64(&blocksDeleted, 1)
+		atomic.AddInt64(&bytesDeleted, b.Properties.ContentLength)
+	}
+
+	var wg sync.WaitGroup
+	todo := make(chan storage.Blob, theConfig.EmptyTrashWorkers)
+	for i := 0; i < 1 || i < theConfig.EmptyTrashWorkers; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for b := range todo {
+				doBlob(b)
+			}
+		}()
+	}
+
+	params := storage.ListBlobsParameters{Include: &storage.IncludeBlobDataset{Metadata: true}}
+	for page := 1; ; page++ {
+		resp, err := v.listBlobs(page, params)
+		if err != nil {
+			log.Printf("EmptyTrash: ListBlobs: %v", err)
+			break
+		}
+		for _, b := range resp.Blobs {
+			todo <- b
+		}
+		if resp.NextMarker == "" {
+			break
+		}
+		params.Marker = resp.NextMarker
+	}
+	close(todo)
+	wg.Wait()
+
+	log.Printf("EmptyTrash stats for %v: Deleted %v bytes in %v blocks. Remaining in trash: %v bytes in %v blocks.", v.String(), bytesDeleted, blocksDeleted, bytesInTrash-bytesDeleted, blocksInTrash-blocksDeleted)
+}
+
+// InternalStats returns bucket I/O and API call counters.
+func (v *AzureBlobVolume) InternalStats() interface{} {
+	return &v.container.stats
+}
+
+type azureBlobStats struct {
+	statsTicker
+	Ops              uint64
+	GetOps           uint64
+	GetRangeOps      uint64
+	GetMetadataOps   uint64
+	GetPropertiesOps uint64
+	CreateOps        uint64
+	SetMetadataOps   uint64
+	DelOps           uint64
+	ListOps          uint64
+}
+
+func (s *azureBlobStats) TickErr(err error) {
+	if err == nil {
+		return
+	}
+	errType := fmt.Sprintf("%T", err)
+	if err, ok := err.(storage.AzureStorageServiceError); ok {
+		errType = errType + fmt.Sprintf(" %d (%s)", err.StatusCode, err.Code)
+	}
+	log.Printf("errType %T, err %s", err, err)
+	s.statsTicker.TickErr(err, errType)
+}
+
+// azureContainer wraps storage.Container in order to count I/O and
+// API usage stats.
+type azureContainer struct {
+	ctr   *storage.Container
+	stats azureBlobStats
+}
+
+func (c *azureContainer) Exists() (bool, error) {
+	c.stats.TickOps("exists")
+	c.stats.Tick(&c.stats.Ops)
+	ok, err := c.ctr.Exists()
+	c.stats.TickErr(err)
+	return ok, err
+}
+
+func (c *azureContainer) GetBlobMetadata(bname string) (storage.BlobMetadata, error) {
+	c.stats.TickOps("get_metadata")
+	c.stats.Tick(&c.stats.Ops, &c.stats.GetMetadataOps)
+	b := c.ctr.GetBlobReference(bname)
+	err := b.GetMetadata(nil)
+	c.stats.TickErr(err)
+	return b.Metadata, err
+}
+
+func (c *azureContainer) GetBlobProperties(bname string) (*storage.BlobProperties, error) {
+	c.stats.TickOps("get_properties")
+	c.stats.Tick(&c.stats.Ops, &c.stats.GetPropertiesOps)
+	b := c.ctr.GetBlobReference(bname)
+	err := b.GetProperties(nil)
+	c.stats.TickErr(err)
+	return &b.Properties, err
+}
+
+func (c *azureContainer) GetBlob(bname string) (io.ReadCloser, error) {
+	c.stats.TickOps("get")
+	c.stats.Tick(&c.stats.Ops, &c.stats.GetOps)
+	b := c.ctr.GetBlobReference(bname)
+	rdr, err := b.Get(nil)
+	c.stats.TickErr(err)
+	return NewCountingReader(rdr, c.stats.TickInBytes), err
+}
+
+func (c *azureContainer) GetBlobRange(bname string, start, end int, opts *storage.GetBlobOptions) (io.ReadCloser, error) {
+	c.stats.TickOps("get_range")
+	c.stats.Tick(&c.stats.Ops, &c.stats.GetRangeOps)
+	b := c.ctr.GetBlobReference(bname)
+	rdr, err := b.GetRange(&storage.GetBlobRangeOptions{
+		Range: &storage.BlobRange{
+			Start: uint64(start),
+			End:   uint64(end),
+		},
+		GetBlobOptions: opts,
+	})
+	c.stats.TickErr(err)
+	return NewCountingReader(rdr, c.stats.TickInBytes), err
+}
+
+// If we give it an io.Reader that doesn't also have a Len() int
+// method, the Azure SDK determines data size by copying the data into
+// a new buffer, which is not a good use of memory.
+type readerWithAzureLen struct {
+	io.Reader
+	len int
+}
+
+// Len satisfies the private lener interface in azure-sdk-for-go.
+func (r *readerWithAzureLen) Len() int {
+	return r.len
+}
+
+func (c *azureContainer) CreateBlockBlobFromReader(bname string, size int, rdr io.Reader, opts *storage.PutBlobOptions) error {
+	c.stats.TickOps("create")
+	c.stats.Tick(&c.stats.Ops, &c.stats.CreateOps)
+	if size != 0 {
+		rdr = &readerWithAzureLen{
+			Reader: NewCountingReader(rdr, c.stats.TickOutBytes),
+			len:    size,
+		}
+	}
+	b := c.ctr.GetBlobReference(bname)
+	err := b.CreateBlockBlobFromReader(rdr, opts)
+	c.stats.TickErr(err)
+	return err
+}
+
+func (c *azureContainer) SetBlobMetadata(bname string, m storage.BlobMetadata, opts *storage.SetBlobMetadataOptions) error {
+	c.stats.TickOps("set_metadata")
+	c.stats.Tick(&c.stats.Ops, &c.stats.SetMetadataOps)
+	b := c.ctr.GetBlobReference(bname)
+	b.Metadata = m
+	err := b.SetMetadata(opts)
+	c.stats.TickErr(err)
+	return err
+}
+
+func (c *azureContainer) ListBlobs(params storage.ListBlobsParameters) (storage.BlobListResponse, error) {
+	c.stats.TickOps("list")
+	c.stats.Tick(&c.stats.Ops, &c.stats.ListOps)
+	resp, err := c.ctr.ListBlobs(params)
+	c.stats.TickErr(err)
+	return resp, err
+}
+
+func (c *azureContainer) DeleteBlob(bname string, opts *storage.DeleteBlobOptions) error {
+	c.stats.TickOps("delete")
+	c.stats.Tick(&c.stats.Ops, &c.stats.DelOps)
+	b := c.ctr.GetBlobReference(bname)
+	err := b.Delete(opts)
+	c.stats.TickErr(err)
+	return err
+}