mirror of
https://github.com/restic/restic.git
synced 2024-08-31 00:27:34 +02:00
249 lines
5.4 KiB
Go
249 lines
5.4 KiB
Go
package s3
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import (
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"bytes"
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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"strings"
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"gopkg.in/amz.v3/aws"
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"gopkg.in/amz.v3/s3"
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"github.com/restic/restic/backend"
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)
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const maxKeysInList = 1000
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const connLimit = 10
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const backendPrefix = "restic"
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func s3path(t backend.Type, name string) string {
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if t == backend.Config {
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return backendPrefix + "/" + string(t)
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}
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return backendPrefix + "/" + string(t) + "/" + name
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}
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type S3Backend struct {
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bucket *s3.Bucket
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connChan chan struct{}
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path string
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}
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// Open a backend using an S3 bucket object
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func OpenS3Bucket(bucket *s3.Bucket, bucketname string) *S3Backend {
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connChan := make(chan struct{}, connLimit)
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for i := 0; i < connLimit; i++ {
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connChan <- struct{}{}
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}
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return &S3Backend{bucket: bucket, path: bucketname, connChan: connChan}
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}
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// Open opens the S3 backend at bucket and region.
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func Open(regionname, bucketname string) (backend.Backend, error) {
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auth, err := aws.EnvAuth()
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if err != nil {
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return nil, err
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}
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client := s3.New(auth, aws.Regions[regionname])
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s3bucket, s3err := client.Bucket(bucketname)
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if s3err != nil {
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return nil, s3err
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}
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return OpenS3Bucket(s3bucket, bucketname), nil
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}
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// Location returns this backend's location (the bucket name).
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func (be *S3Backend) Location() string {
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return be.path
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}
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type s3Blob struct {
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b *S3Backend
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buf *bytes.Buffer
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final bool
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}
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func (bb *s3Blob) Write(p []byte) (int, error) {
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if bb.final {
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return 0, errors.New("blob already closed")
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}
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n, err := bb.buf.Write(p)
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return n, err
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}
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func (bb *s3Blob) Read(p []byte) (int, error) {
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return bb.buf.Read(p)
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}
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func (bb *s3Blob) Close() error {
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bb.final = true
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bb.buf.Reset()
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return nil
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}
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func (bb *s3Blob) Size() uint {
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return uint(bb.buf.Len())
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}
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func (bb *s3Blob) Finalize(t backend.Type, name string) error {
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if bb.final {
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return errors.New("Already finalized")
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}
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bb.final = true
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path := s3path(t, name)
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// Check key does not already exist
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_, err := bb.b.bucket.GetReader(path)
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if err == nil {
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return errors.New("key already exists!")
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}
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<-bb.b.connChan
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err = bb.b.bucket.PutReader(path, bb.buf, int64(bb.buf.Len()), "binary/octet-stream", "private")
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bb.b.connChan <- struct{}{}
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bb.buf.Reset()
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return err
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}
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// Create creates a new Blob. The data is available only after Finalize()
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// has been called on the returned Blob.
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func (be *S3Backend) Create() (backend.Blob, error) {
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blob := s3Blob{
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b: be,
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buf: &bytes.Buffer{},
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}
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return &blob, nil
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}
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// Get returns a reader that yields the content stored under the given
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// name. The reader should be closed after draining it.
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func (be *S3Backend) Get(t backend.Type, name string) (io.ReadCloser, error) {
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path := s3path(t, name)
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return be.bucket.GetReader(path)
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}
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// GetReader returns an io.ReadCloser for the Blob with the given name of
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// type t at offset and length. If length is 0, the reader reads until EOF.
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func (be *S3Backend) GetReader(t backend.Type, name string, offset, length uint) (io.ReadCloser, error) {
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rc, err := be.Get(t, name)
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if err != nil {
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return nil, err
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}
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n, errc := io.CopyN(ioutil.Discard, rc, int64(offset))
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if errc != nil {
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return nil, errc
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} else if n != int64(offset) {
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return nil, fmt.Errorf("less bytes read than expected, read: %d, expected: %d", n, offset)
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}
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if length == 0 {
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return rc, nil
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}
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return backend.LimitReadCloser(rc, int64(length)), nil
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}
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// Test returns true if a blob of the given type and name exists in the backend.
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func (be *S3Backend) Test(t backend.Type, name string) (bool, error) {
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found := false
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path := s3path(t, name)
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_, err := be.bucket.GetReader(path)
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if err == nil {
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found = true
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}
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// If error, then not found
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return found, nil
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}
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// Remove removes the blob with the given name and type.
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func (be *S3Backend) Remove(t backend.Type, name string) error {
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path := s3path(t, name)
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return be.bucket.Del(path)
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}
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// List returns a channel that yields all names of blobs of type t. A
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// goroutine is started for this. If the channel done is closed, sending
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// stops.
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func (be *S3Backend) List(t backend.Type, done <-chan struct{}) <-chan string {
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ch := make(chan string)
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prefix := s3path(t, "")
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listresp, err := be.bucket.List(prefix, "/", "", maxKeysInList)
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if err != nil {
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close(ch)
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return ch
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}
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matches := make([]string, len(listresp.Contents))
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for idx, key := range listresp.Contents {
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matches[idx] = strings.TrimPrefix(key.Key, prefix)
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}
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// Continue making requests to get full list.
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for listresp.IsTruncated {
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listresp, err = be.bucket.List(prefix, "/", listresp.NextMarker, maxKeysInList)
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if err != nil {
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close(ch)
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return ch
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}
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for _, key := range listresp.Contents {
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matches = append(matches, strings.TrimPrefix(key.Key, prefix))
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}
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}
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go func() {
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defer close(ch)
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for _, m := range matches {
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if m == "" {
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continue
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}
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select {
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case ch <- m:
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case <-done:
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return
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}
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}
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}()
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return ch
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}
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// Remove keys for a specified backend type
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func (be *S3Backend) removeKeys(t backend.Type) {
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doneChan := make(chan struct{})
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for key := range be.List(backend.Data, doneChan) {
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be.Remove(backend.Data, key)
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}
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doneChan <- struct{}{}
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}
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// Delete removes all restic keys
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func (be *S3Backend) Delete() error {
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be.removeKeys(backend.Data)
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be.removeKeys(backend.Key)
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be.removeKeys(backend.Lock)
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be.removeKeys(backend.Snapshot)
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be.removeKeys(backend.Index)
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be.removeKeys(backend.Config)
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return nil
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}
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// Close does nothing
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func (be *S3Backend) Close() error { return nil }
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