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Merge pull request #2088 from ahmetalpbalkan/pr-upstream-azure-race-fix

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azure: fix race condition in PutContent()
This commit is contained in:
Derek McGowan 2016-12-06 14:07:53 -08:00 committed by GitHub
commit 15dc1296af
1 changed files with 32 additions and 10 deletions
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42
registry/storage/driver/azure/azure.go
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@ -117,19 +117,33 @@ func (d *driver) GetContent(ctx context.Context, path string) ([]byte, error) {
// PutContent stores the []byte content at a location designated by "path".
func (d *driver) PutContent(ctx context.Context, path string, contents []byte) error {
if _, err := d.client.DeleteBlobIfExists(d.container, path, nil); err != nil {
return err
if limit := 64 * 1024 * 1024; len(contents) > limit { // max size for block blobs uploaded via single "Put Blob"
return fmt.Errorf("uploading %d bytes with PutContent is not supported; limit: %d bytes", len(contents), limit)
}
writer, err := d.Writer(ctx, path, false)
if err != nil {
return err
// Historically, blobs uploaded via PutContent used to be of type AppendBlob
// (https://github.com/docker/distribution/pull/1438). We can't replace
// these blobs atomically via a single "Put Blob" operation without
// deleting them first. Once we detect they are BlockBlob type, we can
// overwrite them with an atomically "Put Blob" operation.
//
// While we delete the blob and create a new one, there will be a small
// window of inconsistency and if the Put Blob fails, we may end up with
// losing the existing data while migrating it to BlockBlob type. However,
// expectation is the clients pushing will be retrying when they get an error
// response.
props, err := d.client.GetBlobProperties(d.container, path)
if err != nil && !is404(err) {
return fmt.Errorf("failed to get blob properties: %v", err)
}
defer writer.Close()
_, err = writer.Write(contents)
if err != nil {
return err
if err == nil && props.BlobType != azure.BlobTypeBlock {
if err := d.client.DeleteBlob(d.container, path, nil); err != nil {
return fmt.Errorf("failed to delete legacy blob (%s): %v", props.BlobType, err)
}
}
return writer.Commit()
r := bytes.NewReader(contents)
return d.client.CreateBlockBlobFromReader(d.container, path, uint64(len(contents)), r, nil)
}
// Reader retrieves an io.ReadCloser for the content stored at "path" with a
@ -383,6 +397,14 @@ func (d *driver) listBlobs(container, virtPath string) ([]string, error) {
}
func is404(err error) bool {
// handle the case when the request was a HEAD and service error could not
// be parsed, such as "storage: service returned without a response body
// (404 The specified blob does not exist.)"
if strings.Contains(fmt.Sprintf("%v", err), "404 The specified blob does not exist") {
return true
}
// common case
statusCodeErr, ok := err.(azure.AzureStorageServiceError)
return ok && statusCodeErr.StatusCode == http.StatusNotFound
}