Add new storage backend: Dropbox (#103)

cmd/backup/config.go

@@ -70,6 +70,8 @@ type Config struct {
 	AzureStorageContainerName     string          `split_words:"true"`
 	AzureStoragePath              string          `split_words:"true"`
 	AzureStorageEndpoint          string          `split_words:"true" default:"https://{{ .AccountName }}.blob.core.windows.net/"`
+	DropboxToken                  string          `split_words:"true"`
+	DropboxRemotePath             string          `split_words:"true"`
 }
 
 func (c *Config) resolveSecret(envVar string, secretPath string) (string, error) {

cmd/backup/script.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/offen/docker-volume-backup/internal/storage"
 	"github.com/offen/docker-volume-backup/internal/storage/azure"
+	"github.com/offen/docker-volume-backup/internal/storage/dropbox"
 	"github.com/offen/docker-volume-backup/internal/storage/local"
 	"github.com/offen/docker-volume-backup/internal/storage/s3"
 	"github.com/offen/docker-volume-backup/internal/storage/ssh"
@@ -75,6 +76,7 @@ func newScript() (*script, error) {
 				"SSH":     {},
 				"Local":   {},
 				"Azure":   {},
+				"Dropbox": {},
 			},
 		},
 	}
@@ -218,6 +220,18 @@ func newScript() (*script, error) {
 		s.storages = append(s.storages, azureBackend)
 	}
 
+	if s.c.DropboxToken != "" {
+		dropboxConfig := dropbox.Config{
+			Token:      s.c.DropboxToken,
+			RemotePath: s.c.DropboxRemotePath,
+		}
+		dropboxBackend, err := dropbox.NewStorageBackend(dropboxConfig, logFunc)
+		if err != nil {
+			return nil, err
+		}
+		s.storages = append(s.storages, dropboxBackend)
+	}
+
 	if s.c.EmailNotificationRecipient != "" {
 		emailURL := fmt.Sprintf(
 			"smtp://%s:%s@%s:%d/?from=%s&to=%s",

go.mod

@@ -20,6 +20,13 @@ require (
 	golang.org/x/sync v0.3.0
 )
 
+require (
+	github.com/golang/protobuf v1.5.2 // indirect
+	golang.org/x/oauth2 v0.0.0-20221014153046-6fdb5e3db783 // indirect
+	google.golang.org/appengine v1.6.7 // indirect
+	google.golang.org/protobuf v1.28.1 // indirect
+)
+
 require (
 	github.com/Azure/azure-sdk-for-go/sdk/azcore v1.6.0 // indirect
 	github.com/Azure/azure-sdk-for-go/sdk/internal v1.3.0 // indirect
@@ -28,6 +35,7 @@ require (
 	github.com/docker/distribution v2.8.2+incompatible // indirect
 	github.com/docker/go-connections v0.4.0 // indirect
 	github.com/docker/go-units v0.4.0 // indirect
+	github.com/dropbox/dropbox-sdk-go-unofficial/v6 v6.0.5
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/fatih/color v1.13.0 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect

go.sum

@@ -257,6 +257,8 @@ github.com/docker/go-connections v0.4.0 h1:El9xVISelRB7BuFusrZozjnkIM5YnzCViNKoh
 github.com/docker/go-connections v0.4.0/go.mod h1:Gbd7IOopHjR8Iph03tsViu4nIes5XhDvyHbTtUxmeec=
 github.com/docker/go-units v0.4.0 h1:3uh0PgVws3nIA0Q+MwDC8yjEPf9zjRfZZWXZYDct3Tw=
 github.com/docker/go-units v0.4.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk=
+github.com/dropbox/dropbox-sdk-go-unofficial/v6 v6.0.5 h1:FT+t0UEDykcor4y3dMVKXIiWJETBpRgERYTGlmMd7HU=
+github.com/dropbox/dropbox-sdk-go-unofficial/v6 v6.0.5/go.mod h1:rSS3kM9XMzSQ6pw91Qgd6yB5jdt70N4OdtrAf74As5M=
 github.com/dustin/go-humanize v1.0.0/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
@@ -785,6 +787,7 @@ golang.org/x/oauth2 v0.0.0-20220608161450-d0670ef3b1eb/go.mod h1:jaDAt6Dkxork7Lm
 golang.org/x/oauth2 v0.0.0-20220622183110-fd043fe589d2/go.mod h1:jaDAt6Dkxork7LmZnYtzbRWj0W47D86a3TGe0YHBvmE=
 golang.org/x/oauth2 v0.0.0-20220822191816-0ebed06d0094/go.mod h1:h4gKUeWbJ4rQPri7E0u6Gs4e9Ri2zaLxzw5DI5XGrYg=
 golang.org/x/oauth2 v0.0.0-20220909003341-f21342109be1/go.mod h1:h4gKUeWbJ4rQPri7E0u6Gs4e9Ri2zaLxzw5DI5XGrYg=
+golang.org/x/oauth2 v0.0.0-20221014153046-6fdb5e3db783 h1:nt+Q6cXKz4MosCSpnbMtqiQ8Oz0pxTef2B4Vca2lvfk=
 golang.org/x/oauth2 v0.0.0-20221014153046-6fdb5e3db783/go.mod h1:h4gKUeWbJ4rQPri7E0u6Gs4e9Ri2zaLxzw5DI5XGrYg=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
@@ -1046,6 +1049,7 @@ google.golang.org/appengine v1.5.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7
 google.golang.org/appengine v1.6.1/go.mod h1:i06prIuMbXzDqacNJfV5OdTW448YApPu5ww/cMBSeb0=
 google.golang.org/appengine v1.6.5/go.mod h1:8WjMMxjGQR8xUklV/ARdw2HLXBOI7O7uCIDZVag1xfc=
 google.golang.org/appengine v1.6.6/go.mod h1:8WjMMxjGQR8xUklV/ARdw2HLXBOI7O7uCIDZVag1xfc=
+google.golang.org/appengine v1.6.7 h1:FZR1q0exgwxzPzp/aF+VccGrSfxfPpkBqjIIEq3ru6c=
 google.golang.org/appengine v1.6.7/go.mod h1:8WjMMxjGQR8xUklV/ARdw2HLXBOI7O7uCIDZVag1xfc=
 google.golang.org/genproto v0.0.0-20180817151627-c66870c02cf8/go.mod h1:JiN7NxoALGmiZfu7CAH4rXhgtRTLTxftemlI0sWmxmc=
 google.golang.org/genproto v0.0.0-20190307195333-5fe7a883aa19/go.mod h1:VzzqZJRnGkLBvHegQrXjBqPurQTc5/KpmUdxsrq26oE=

internal/storage/dropbox/dropbox.go

@@ -0,0 +1,182 @@
+package dropbox
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"path"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"time"
+
+	"github.com/dropbox/dropbox-sdk-go-unofficial/v6/dropbox"
+	"github.com/dropbox/dropbox-sdk-go-unofficial/v6/dropbox/files"
+	"github.com/offen/docker-volume-backup/internal/storage"
+)
+
+type dropboxStorage struct {
+	*storage.StorageBackend
+	client files.Client
+}
+
+// Config allows to configure a Dropbox storage backend.
+type Config struct {
+	Token      string
+	RemotePath string
+}
+
+// NewStorageBackend creates and initializes a new Dropbox storage backend.
+func NewStorageBackend(opts Config, logFunc storage.Log) (storage.Backend, error) {
+	if opts.Token == "" {
+		return nil, errors.New("NewStorageBackend: No Dropbox token has been provided")
+	} else {
+		config := dropbox.Config{
+			Token: opts.Token,
+		}
+
+		client := files.New(config)
+
+		return &dropboxStorage{
+			StorageBackend: &storage.StorageBackend{
+				DestinationPath: opts.RemotePath,
+				Log:             logFunc,
+			},
+			client: client,
+		}, nil
+	}
+}
+
+// Name returns the name of the storage backend
+func (b *dropboxStorage) Name() string {
+	return "Dropbox"
+}
+
+// Copy copies the given file to the WebDav storage backend.
+func (b *dropboxStorage) Copy(file string) error {
+	_, name := path.Split(file)
+
+	folderArg := files.NewCreateFolderArg(b.DestinationPath)
+	if _, err := b.client.CreateFolderV2(folderArg); err != nil {
+		if err.(files.CreateFolderV2APIError).EndpointError.Path.Tag == files.WriteErrorConflict {
+			b.Log(storage.LogLevelInfo, b.Name(), "Destination path '%s' already exists in Dropbox, no new directory required.", b.DestinationPath)
+		} else {
+			return fmt.Errorf("(*dropboxStorage).Copy: Error creating directory '%s' in Dropbox: %w", b.DestinationPath, err)
+		}
+	}
+
+	r, err := os.Open(file)
+	if err != nil {
+		return fmt.Errorf("(*dropboxStorage).Copy: Error opening the file to be uploaded: %w", err)
+	}
+	defer r.Close()
+
+	// Start new upload session and get session id
+
+	b.Log(storage.LogLevelInfo, b.Name(), "Starting upload session for backup '%s' to Dropbox at path '%s'.", file, b.DestinationPath)
+
+	var sessionId string
+	uploadSessionStartArg := files.NewUploadSessionStartArg()
+	uploadSessionStartArg.SessionType = &files.UploadSessionType{Tagged: dropbox.Tagged{Tag: files.UploadSessionTypeConcurrent}}
+	if res, err := b.client.UploadSessionStart(uploadSessionStartArg, nil); err != nil {
+		return fmt.Errorf("(*dropboxStorage).Copy: Error starting the upload session: %w", err)
+	} else {
+		sessionId = res.SessionId
+	}
+
+	// Send the file in 148MB chunks (Dropbox API limit is 150MB, concurrent upload requires a multiple of 4MB though)
+	// Last append can be any size <= 150MB with Close=True
+
+	const chunkSize = 148 * 1024 * 1024 // 148MB
+	var offset uint64 = 0
+
+	for {
+		chunk := make([]byte, chunkSize)
+		bytesRead, err := r.Read(chunk)
+		if err != nil {
+			return fmt.Errorf("(*dropboxStorage).Copy: Error reading the file to be uploaded: %w", err)
+		}
+		chunk = chunk[:bytesRead]
+
+		uploadSessionAppendArg := files.NewUploadSessionAppendArg(
+			files.NewUploadSessionCursor(sessionId, offset),
+		)
+		isEOF := bytesRead < chunkSize
+		uploadSessionAppendArg.Close = isEOF
+
+		if err := b.client.UploadSessionAppendV2(uploadSessionAppendArg, bytes.NewReader(chunk)); err != nil {
+			return fmt.Errorf("(*dropboxStorage).Copy: Error appending the file to the upload session: %w", err)
+		}
+
+		if isEOF {
+			break
+		}
+
+		offset += uint64(bytesRead)
+	}
+
+	// Finish the upload session, commit the file (no new data added)
+
+	b.client.UploadSessionFinish(
+		files.NewUploadSessionFinishArg(
+			files.NewUploadSessionCursor(sessionId, 0),
+			files.NewCommitInfo(filepath.Join(b.DestinationPath, name)),
+		), nil)
+
+	b.Log(storage.LogLevelInfo, b.Name(), "Uploaded a copy of backup '%s' to Dropbox at path '%s'.", file, b.DestinationPath)
+
+	return nil
+}
+
+// Prune rotates away backups according to the configuration and provided deadline for the Dropbox storage backend.
+func (b *dropboxStorage) Prune(deadline time.Time, pruningPrefix string) (*storage.PruneStats, error) {
+	var entries []files.IsMetadata
+	res, err := b.client.ListFolder(files.NewListFolderArg(b.DestinationPath))
+	if err != nil {
+		return nil, fmt.Errorf("(*webDavStorage).Prune: Error looking up candidates from remote storage: %w", err)
+	}
+	entries = append(entries, res.Entries...)
+
+	for res.HasMore {
+		res, err = b.client.ListFolderContinue(files.NewListFolderContinueArg(res.Cursor))
+		if err != nil {
+			return nil, fmt.Errorf("(*webDavStorage).Prune: Error looking up candidates from remote storage: %w", err)
+		}
+		entries = append(entries, res.Entries...)
+	}
+
+	var matches []*files.FileMetadata
+	var lenCandidates int
+	for _, candidate := range entries {
+		if reflect.Indirect(reflect.ValueOf(candidate)).Type() != reflect.TypeOf(files.FileMetadata{}) {
+			continue
+		}
+		candidate := candidate.(*files.FileMetadata)
+		if !strings.HasPrefix(candidate.Name, pruningPrefix) {
+			continue
+		}
+		lenCandidates++
+		if candidate.ServerModified.Before(deadline) {
+			matches = append(matches, candidate)
+		}
+	}
+
+	stats := &storage.PruneStats{
+		Total:  uint(lenCandidates),
+		Pruned: uint(len(matches)),
+	}
+
+	if err := b.DoPrune(b.Name(), len(matches), lenCandidates, "Dropbox backup(s)", func() error {
+		for _, match := range matches {
+			if _, err := b.client.DeleteV2(files.NewDeleteArg(filepath.Join(b.DestinationPath, match.Name))); err != nil {
+				return fmt.Errorf("(*dropboxStorage).Prune: Error removing file from Dropbox storage: %w", err)
+			}
+		}
+		return nil
+	}); err != nil {
+		return stats, err
+	}
+
+	return stats, nil
+}