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restic/internal/backend/gs/gs.go
2020-10-03 18:55:56 +02:00

431 lines
11 KiB
Go

// Package gs provides a restic backend for Google Cloud Storage.
package gs
import (
"context"
"io"
"net/http"
"os"
"path"
"strings"
"cloud.google.com/go/storage"
"github.com/pkg/errors"
"github.com/restic/restic/internal/backend"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/restic"
"golang.org/x/oauth2"
"golang.org/x/oauth2/google"
"google.golang.org/api/googleapi"
"google.golang.org/api/iterator"
"google.golang.org/api/option"
)
// Backend stores data in a GCS bucket.
//
// The service account used to access the bucket must have these permissions:
// * storage.objects.create
// * storage.objects.delete
// * storage.objects.get
// * storage.objects.list
type Backend struct {
gcsClient *storage.Client
projectID string
sem *backend.Semaphore
bucketName string
bucket *storage.BucketHandle
prefix string
listMaxItems int
backend.Layout
}
// Ensure that *Backend implements restic.Backend.
var _ restic.Backend = &Backend{}
func getStorageClient(rt http.RoundTripper) (*storage.Client, error) {
// create a new HTTP client
httpClient := &http.Client{
Transport: rt,
}
// create a new context with the HTTP client stored at the oauth2.HTTPClient key
ctx := context.WithValue(context.Background(), oauth2.HTTPClient, httpClient)
var ts oauth2.TokenSource
if token := os.Getenv("GOOGLE_ACCESS_TOKEN"); token != "" {
ts = oauth2.StaticTokenSource(&oauth2.Token{
AccessToken: token,
TokenType: "Bearer",
})
} else {
var err error
ts, err = google.DefaultTokenSource(ctx, storage.ScopeReadWrite)
if err != nil {
return nil, err
}
}
oauthClient := oauth2.NewClient(ctx, ts)
gcsClient, err := storage.NewClient(ctx, option.WithHTTPClient(oauthClient))
if err != nil {
return nil, err
}
return gcsClient, nil
}
func (be *Backend) bucketExists(ctx context.Context, bucket *storage.BucketHandle) (bool, error) {
_, err := bucket.Attrs(ctx)
if err == storage.ErrBucketNotExist {
return false, nil
}
return err == nil, err
}
const defaultListMaxItems = 1000
func open(cfg Config, rt http.RoundTripper) (*Backend, error) {
debug.Log("open, config %#v", cfg)
gcsClient, err := getStorageClient(rt)
if err != nil {
return nil, errors.Wrap(err, "getStorageClient")
}
sem, err := backend.NewSemaphore(cfg.Connections)
if err != nil {
return nil, err
}
be := &Backend{
gcsClient: gcsClient,
projectID: cfg.ProjectID,
sem: sem,
bucketName: cfg.Bucket,
bucket: gcsClient.Bucket(cfg.Bucket),
prefix: cfg.Prefix,
Layout: &backend.DefaultLayout{
Path: cfg.Prefix,
Join: path.Join,
},
listMaxItems: defaultListMaxItems,
}
return be, nil
}
// Open opens the gs backend at the specified bucket.
func Open(cfg Config, rt http.RoundTripper) (restic.Backend, error) {
return open(cfg, rt)
}
// Create opens the gs backend at the specified bucket and attempts to creates
// the bucket if it does not exist yet.
//
// The service account must have the "storage.buckets.create" permission to
// create a bucket the does not yet exist.
func Create(cfg Config, rt http.RoundTripper) (restic.Backend, error) {
be, err := open(cfg, rt)
if err != nil {
return nil, errors.Wrap(err, "open")
}
// Try to determine if the bucket exists. If it does not, try to create it.
ctx := context.Background()
exists, err := be.bucketExists(ctx, be.bucket)
if err != nil {
return nil, errors.Wrap(err, "service.Buckets.Get")
}
if !exists {
// Bucket doesn't exist, try to create it.
if err := be.bucket.Create(ctx, be.projectID, nil); err != nil {
// Always an error, as the bucket definitely doesn't exist.
return nil, errors.Wrap(err, "service.Buckets.Insert")
}
}
return be, nil
}
// SetListMaxItems sets the number of list items to load per request.
func (be *Backend) SetListMaxItems(i int) {
be.listMaxItems = i
}
// IsNotExist returns true if the error is caused by a not existing file.
func (be *Backend) IsNotExist(err error) bool {
debug.Log("IsNotExist(%T, %#v)", err, err)
if os.IsNotExist(err) {
return true
}
if er, ok := err.(*googleapi.Error); ok {
if er.Code == 404 {
return true
}
}
return false
}
// Join combines path components with slashes.
func (be *Backend) Join(p ...string) string {
return path.Join(p...)
}
// Location returns this backend's location (the bucket name).
func (be *Backend) Location() string {
return be.Join(be.bucketName, be.prefix)
}
// Path returns the path in the bucket that is used for this backend.
func (be *Backend) Path() string {
return be.prefix
}
// Save stores data in the backend at the handle.
func (be *Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader) error {
if err := h.Valid(); err != nil {
return err
}
objName := be.Filename(h)
debug.Log("Save %v at %v", h, objName)
be.sem.GetToken()
debug.Log("InsertObject(%v, %v)", be.bucketName, objName)
// Set chunk size to zero to disable resumable uploads.
//
// With a non-zero chunk size (the default is
// googleapi.DefaultUploadChunkSize, 8MB), Insert will buffer data from
// rd in chunks of this size so it can upload these chunks in
// individual requests.
//
// This chunking allows the library to automatically handle network
// interruptions and re-upload only the last chunk rather than the full
// file.
//
// Unfortunately, this buffering doesn't play nicely with
// --limit-upload, which applies a rate limit to rd. This rate limit
// ends up only limiting the read from rd into the buffer rather than
// the network traffic itself. This results in poor network rate limit
// behavior, where individual chunks are written to the network at full
// bandwidth for several seconds, followed by several seconds of no
// network traffic as the next chunk is read through the rate limiter.
//
// By disabling chunking, rd is passed further down the request stack,
// where there is less (but some) buffering, which ultimately results
// in better rate limiting behavior.
//
// restic typically writes small blobs (4MB-30MB), so the resumable
// uploads are not providing significant benefit anyways.
w := be.bucket.Object(objName).NewWriter(ctx)
w.ChunkSize = 0
wbytes, err := io.Copy(w, rd)
w.Close()
be.sem.ReleaseToken()
if err != nil {
debug.Log("%v: err %#v: %v", objName, err, err)
return errors.Wrap(err, "service.Objects.Insert")
}
debug.Log("%v -> %v bytes", objName, wbytes)
return nil
}
// wrapReader wraps an io.ReadCloser to run an additional function on Close.
type wrapReader struct {
io.ReadCloser
f func()
}
func (wr wrapReader) Close() error {
err := wr.ReadCloser.Close()
wr.f()
return err
}
// Load runs fn with a reader that yields the contents of the file at h at the
// given offset.
func (be *Backend) Load(ctx context.Context, h restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
return backend.DefaultLoad(ctx, h, length, offset, be.openReader, fn)
}
func (be *Backend) openReader(ctx context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error) {
debug.Log("Load %v, length %v, offset %v from %v", h, length, offset, be.Filename(h))
if err := h.Valid(); err != nil {
return nil, err
}
if offset < 0 {
return nil, errors.New("offset is negative")
}
if length < 0 {
return nil, errors.Errorf("invalid length %d", length)
}
if length == 0 {
// negative length indicates read till end to GCS lib
length = -1
}
objName := be.Filename(h)
be.sem.GetToken()
r, err := be.bucket.Object(objName).NewRangeReader(ctx, offset, int64(length))
if err != nil {
be.sem.ReleaseToken()
return nil, err
}
closeRd := wrapReader{
ReadCloser: r,
f: func() {
debug.Log("Close()")
be.sem.ReleaseToken()
},
}
return closeRd, err
}
// Stat returns information about a blob.
func (be *Backend) Stat(ctx context.Context, h restic.Handle) (bi restic.FileInfo, err error) {
debug.Log("%v", h)
objName := be.Filename(h)
be.sem.GetToken()
attr, err := be.bucket.Object(objName).Attrs(ctx)
be.sem.ReleaseToken()
if err != nil {
debug.Log("GetObjectAttributes() err %v", err)
return restic.FileInfo{}, errors.Wrap(err, "service.Objects.Get")
}
return restic.FileInfo{Size: attr.Size, Name: h.Name}, nil
}
// Test returns true if a blob of the given type and name exists in the backend.
func (be *Backend) Test(ctx context.Context, h restic.Handle) (bool, error) {
found := false
objName := be.Filename(h)
be.sem.GetToken()
_, err := be.bucket.Object(objName).Attrs(ctx)
be.sem.ReleaseToken()
if err == nil {
found = true
}
// If error, then not found
return found, nil
}
// Remove removes the blob with the given name and type.
func (be *Backend) Remove(ctx context.Context, h restic.Handle) error {
objName := be.Filename(h)
be.sem.GetToken()
err := be.bucket.Object(objName).Delete(ctx)
be.sem.ReleaseToken()
if err == storage.ErrObjectNotExist {
err = nil
}
debug.Log("Remove(%v) at %v -> err %v", h, objName, err)
return errors.Wrap(err, "client.RemoveObject")
}
// List runs fn for each file in the backend which has the type t. When an
// error occurs (or fn returns an error), List stops and returns it.
func (be *Backend) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error {
debug.Log("listing %v", t)
prefix, _ := be.Basedir(t)
// make sure prefix ends with a slash
if !strings.HasSuffix(prefix, "/") {
prefix += "/"
}
ctx, cancel := context.WithCancel(ctx)
defer cancel()
itr := be.bucket.Objects(ctx, &storage.Query{Prefix: prefix})
for {
be.sem.GetToken()
attrs, err := itr.Next()
be.sem.ReleaseToken()
if err == iterator.Done {
break
}
if err != nil {
return err
}
m := strings.TrimPrefix(attrs.Name, prefix)
if m == "" {
continue
}
fi := restic.FileInfo{
Name: path.Base(m),
Size: int64(attrs.Size),
}
err = fn(fi)
if err != nil {
return err
}
if ctx.Err() != nil {
return ctx.Err()
}
}
return ctx.Err()
}
// Remove keys for a specified backend type.
func (be *Backend) removeKeys(ctx context.Context, t restic.FileType) error {
return be.List(ctx, t, func(fi restic.FileInfo) error {
return be.Remove(ctx, restic.Handle{Type: t, Name: fi.Name})
})
}
// Delete removes all restic keys in the bucket. It will not remove the bucket itself.
func (be *Backend) Delete(ctx context.Context) error {
alltypes := []restic.FileType{
restic.PackFile,
restic.KeyFile,
restic.LockFile,
restic.SnapshotFile,
restic.IndexFile}
for _, t := range alltypes {
err := be.removeKeys(ctx, t)
if err != nil {
return nil
}
}
return be.Remove(ctx, restic.Handle{Type: restic.ConfigFile})
}
// Close does nothing.
func (be *Backend) Close() error { return nil }