Merge pull request #187 from mtrmac/api-changes

Update for mtrmac/image:api-changes

cmd/skopeo/inspect.go

@@ -39,6 +39,8 @@ var inspectCmd = cli.Command{
 		if err != nil {
 			return err
 		}
+		defer img.Close()
+
 		rawManifest, _, err := img.Manifest()
 		if err != nil {
 			return err

cmd/skopeo/layers.go

@@ -26,6 +26,8 @@ var layersCmd = cli.Command{
 			return err
 		}
 		src := image.FromSource(rawSource)
+		defer src.Close()
+
 		blobDigests := c.Args().Tail()
 		if len(blobDigests) == 0 {
 			b, err := src.BlobDigests()
@@ -46,6 +48,23 @@ var layersCmd = cli.Command{
 		if err != nil {
 			return err
 		}
+		defer dest.Close()
+
+		for _, digest := range blobDigests {
+			if !strings.HasPrefix(digest, "sha256:") {
+				digest = "sha256:" + digest
+			}
+			r, blobSize, err := rawSource.GetBlob(digest)
+			if err != nil {
+				return err
+			}
+			if err := dest.PutBlob(digest, blobSize, r); err != nil {
+				r.Close()
+				return err
+			}
+			r.Close()
+		}
+
 		manifest, _, err := src.Manifest()
 		if err != nil {
 			return err
@@ -53,20 +72,11 @@ var layersCmd = cli.Command{
 		if err := dest.PutManifest(manifest); err != nil {
 			return err
 		}
-		for _, digest := range blobDigests {
-			if !strings.HasPrefix(digest, "sha256:") {
-				digest = "sha256:" + digest
-			}
-			r, _, err := rawSource.GetBlob(digest)
-			if err != nil {
-				return err
-			}
-			if err := dest.PutBlob(digest, r); err != nil {
-				r.Close()
-				return err
-			}
-			r.Close()
+
+		if err := dest.Commit(); err != nil {
+			return err
 		}
+
 		return nil
 	},
 }

cmd/skopeo/utils.go

@@ -17,6 +17,7 @@ func contextFromGlobalOptions(c *cli.Context) *types.SystemContext {
 }
 
 // ParseImage converts image URL-like string to an initialized handler for that image.
+// The caller must call .Close() on the returned Image.
 func parseImage(c *cli.Context) (types.Image, error) {
 	imgName := c.Args().First()
 	ref, err := transports.ParseImageName(imgName)
@@ -28,6 +29,7 @@ func parseImage(c *cli.Context) (types.Image, error) {
 
 // parseImageSource converts image URL-like string to an ImageSource.
 // requestedManifestMIMETypes is as in types.ImageReference.NewImageSource.
+// The caller must call .Close() on the returned ImageSource.
 func parseImageSource(c *cli.Context, name string, requestedManifestMIMETypes []string) (types.ImageSource, error) {
 	ref, err := transports.ParseImageName(name)
 	if err != nil {

vendor/github.com/containers/image/copy/copy.go

@@ -86,11 +86,14 @@ func Image(ctx *types.SystemContext, policyContext *signature.PolicyContext, des
 	if err != nil {
 		return fmt.Errorf("Error initializing destination %s: %v", transports.ImageName(destRef), err)
 	}
+	defer dest.Close()
+
 	rawSource, err := srcRef.NewImageSource(ctx, dest.SupportedManifestMIMETypes())
 	if err != nil {
 		return fmt.Errorf("Error initializing source %s: %v", transports.ImageName(srcRef), err)
 	}
 	src := image.FromSource(rawSource)
+	defer src.Close()
 
 	// Please keep this policy check BEFORE reading any other information about the image.
 	if allowed, err := policyContext.IsRunningImageAllowed(src); !allowed || err != nil { // Be paranoid and fail if either return value indicates so.
@@ -119,8 +122,7 @@ func Image(ctx *types.SystemContext, policyContext *signature.PolicyContext, des
 		return fmt.Errorf("Error parsing manifest: %v", err)
 	}
 	for _, digest := range blobDigests {
-		// TODO(mitr): do not ignore the size param returned here
-		stream, _, err := rawSource.GetBlob(digest)
+		stream, blobSize, err := rawSource.GetBlob(digest)
 		if err != nil {
 			return fmt.Errorf("Error reading blob %s: %v", digest, err)
 		}
@@ -135,7 +137,7 @@ func Image(ctx *types.SystemContext, policyContext *signature.PolicyContext, des
 		if err != nil {
 			return fmt.Errorf("Error preparing to verify blob %s: %v", digest, err)
 		}
-		if err := dest.PutBlob(digest, digestingReader); err != nil {
+		if err := dest.PutBlob(digest, blobSize, digestingReader); err != nil {
 			return fmt.Errorf("Error writing blob: %v", err)
 		}
 		if digestingReader.validationFailed { // Coverage: This should never happen.
@@ -160,7 +162,6 @@ func Image(ctx *types.SystemContext, policyContext *signature.PolicyContext, des
 		sigs = append(sigs, newSig)
 	}
 
-	// FIXME: We need to call PutManifest after PutBlob and before PutSignatures. This seems ugly; move to a "set properties" + "commit" model?
 	if err := dest.PutManifest(manifest); err != nil {
 		return fmt.Errorf("Error writing manifest: %v", err)
 	}
@@ -168,5 +169,10 @@ func Image(ctx *types.SystemContext, policyContext *signature.PolicyContext, des
 	if err := dest.PutSignatures(sigs); err != nil {
 		return fmt.Errorf("Error writing signatures: %v", err)
 	}
+
+	if err := dest.Commit(); err != nil {
+		return fmt.Errorf("Error committing the finished image: %v", err)
+	}
+
 	return nil
 }

vendor/github.com/containers/image/directory/directory_dest.go

@@ -1,6 +1,7 @@
 package directory
 
 import (
+	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
@@ -24,20 +25,20 @@ func (d *dirImageDestination) Reference() types.ImageReference {
 	return d.ref
 }
 
+// Close removes resources associated with an initialized ImageDestination, if any.
+func (d *dirImageDestination) Close() {
+}
+
 func (d *dirImageDestination) SupportedManifestMIMETypes() []string {
 	return nil
 }
 
-func (d *dirImageDestination) PutManifest(manifest []byte) error {
-	return ioutil.WriteFile(d.ref.manifestPath(), manifest, 0644)
-}
-
 // PutBlob writes contents of stream as a blob identified by digest.
+// The length of stream is expected to be expectedSize; if expectedSize == -1, it is not known.
 // WARNING: The contents of stream are being verified on the fly.  Until stream.Read() returns io.EOF, the contents of the data SHOULD NOT be available
 // to any other readers for download using the supplied digest.
 // If stream.Read() at any time, ESPECIALLY at end of input, returns an error, PutBlob MUST 1) fail, and 2) delete any data stored so far.
-// Note: Calling PutBlob() and other methods may have ordering dependencies WRT other methods of this type. FIXME: Figure out and document.
-func (d *dirImageDestination) PutBlob(digest string, stream io.Reader) error {
+func (d *dirImageDestination) PutBlob(digest string, expectedSize int64, stream io.Reader) error {
 	blobPath := d.ref.layerPath(digest)
 	blobFile, err := ioutil.TempFile(filepath.Dir(blobPath), filepath.Base(blobPath))
 	if err != nil {
@@ -51,9 +52,13 @@ func (d *dirImageDestination) PutBlob(digest string, stream io.Reader) error {
 		}
 	}()
 
-	if _, err := io.Copy(blobFile, stream); err != nil {
+	size, err := io.Copy(blobFile, stream)
+	if err != nil {
 		return err
 	}
+	if expectedSize != -1 && size != expectedSize {
+		return fmt.Errorf("Size mismatch when copying %s, expected %d, got %d", digest, expectedSize, size)
+	}
 	if err := blobFile.Sync(); err != nil {
 		return err
 	}
@@ -67,6 +72,10 @@ func (d *dirImageDestination) PutBlob(digest string, stream io.Reader) error {
 	return nil
 }
 
+func (d *dirImageDestination) PutManifest(manifest []byte) error {
+	return ioutil.WriteFile(d.ref.manifestPath(), manifest, 0644)
+}
+
 func (d *dirImageDestination) PutSignatures(signatures [][]byte) error {
 	for i, sig := range signatures {
 		if err := ioutil.WriteFile(d.ref.signaturePath(i), sig, 0644); err != nil {
@@ -75,3 +84,11 @@ func (d *dirImageDestination) PutSignatures(signatures [][]byte) error {
 	}
 	return nil
 }
+
+// Commit marks the process of storing the image as successful and asks for the image to be persisted.
+// WARNING: This does not have any transactional semantics:
+// - Uploaded data MAY be visible to others before Commit() is called
+// - Uploaded data MAY be removed or MAY remain around if Close() is called without Commit() (i.e. rollback is allowed but not guaranteed)
+func (d *dirImageDestination) Commit() error {
+	return nil
+}

vendor/github.com/containers/image/directory/directory_src.go

@@ -13,6 +13,7 @@ type dirImageSource struct {
 }
 
 // newImageSource returns an ImageSource reading from an existing directory.
+// The caller must call .Close() on the returned ImageSource.
 func newImageSource(ref dirReference) types.ImageSource {
 	return &dirImageSource{ref}
 }
@@ -23,6 +24,10 @@ func (s *dirImageSource) Reference() types.ImageReference {
 	return s.ref
 }
 
+// Close removes resources associated with an initialized ImageSource, if any.
+func (s *dirImageSource) Close() {
+}
+
 // it's up to the caller to determine the MIME type of the returned manifest's bytes
 func (s *dirImageSource) GetManifest() ([]byte, string, error) {
 	m, err := ioutil.ReadFile(s.ref.manifestPath())
@@ -32,6 +37,7 @@ func (s *dirImageSource) GetManifest() ([]byte, string, error) {
 	return m, "", err
 }
 
+// GetBlob returns a stream for the specified blob, and the blob’s size (or -1 if unknown).
 func (s *dirImageSource) GetBlob(digest string) (io.ReadCloser, int64, error) {
 	r, err := os.Open(s.ref.layerPath(digest))
 	if err != nil {

vendor/github.com/containers/image/directory/directory_transport.go

@@ -128,19 +128,22 @@ func (ref dirReference) PolicyConfigurationNamespaces() []string {
 }
 
 // NewImage returns a types.Image for this reference.
+// The caller must call .Close() on the returned Image.
 func (ref dirReference) NewImage(ctx *types.SystemContext) (types.Image, error) {
 	src := newImageSource(ref)
 	return image.FromSource(src), nil
 }
 
 // NewImageSource returns a types.ImageSource for this reference,
-// asking the backend to use a manifest from requestedManifestMIMETypes if possible
+// asking the backend to use a manifest from requestedManifestMIMETypes if possible.
 // nil requestedManifestMIMETypes means manifest.DefaultRequestedManifestMIMETypes.
+// The caller must call .Close() on the returned ImageSource.
 func (ref dirReference) NewImageSource(ctx *types.SystemContext, requestedManifestMIMETypes []string) (types.ImageSource, error) {
 	return newImageSource(ref), nil
 }
 
 // NewImageDestination returns a types.ImageDestination for this reference.
+// The caller must call .Close() on the returned ImageDestination.
 func (ref dirReference) NewImageDestination(ctx *types.SystemContext) (types.ImageDestination, error) {
 	return newImageDestination(ref), nil
 }

vendor/github.com/containers/image/docker/docker_client.go

@@ -99,16 +99,20 @@ func (c *dockerClient) makeRequest(method, url string, headers map[string][]stri
 	}
 
 	url = fmt.Sprintf(baseURL, c.scheme, c.registry) + url
-	return c.makeRequestToResolvedURL(method, url, headers, stream)
+	return c.makeRequestToResolvedURL(method, url, headers, stream, -1)
 }
 
 // makeRequestToResolvedURL creates and executes a http.Request with the specified parameters, adding authentication and TLS options for the Docker client.
+// streamLen, if not -1, specifies the length of the data expected on stream.
 // makeRequest should generally be preferred.
-func (c *dockerClient) makeRequestToResolvedURL(method, url string, headers map[string][]string, stream io.Reader) (*http.Response, error) {
+func (c *dockerClient) makeRequestToResolvedURL(method, url string, headers map[string][]string, stream io.Reader, streamLen int64) (*http.Response, error) {
 	req, err := http.NewRequest(method, url, stream)
 	if err != nil {
 		return nil, err
 	}
+	if streamLen != -1 { // Do not blindly overwrite if streamLen == -1, http.NewRequest above can figure out the length of bytes.Reader and similar objects without us having to compute it.
+		req.ContentLength = streamLen
+	}
 	req.Header.Set("Docker-Distribution-API-Version", "registry/2.0")
 	for n, h := range headers {
 		for _, hh := range h {

vendor/github.com/containers/image/docker/docker_image.go

@@ -18,6 +18,7 @@ type Image struct {
 
 // newImage returns a new Image interface type after setting up
 // a client to the registry hosting the given image.
+// The caller must call .Close() on the returned Image.
 func newImage(ctx *types.SystemContext, ref dockerReference) (types.Image, error) {
 	s, err := newImageSource(ctx, ref, nil)
 	if err != nil {

vendor/github.com/containers/image/docker/docker_image_dest.go

@@ -35,6 +35,10 @@ func (d *dockerImageDestination) Reference() types.ImageReference {
 	return d.ref
 }
 
+// Close removes resources associated with an initialized ImageDestination, if any.
+func (d *dockerImageDestination) Close() {
+}
+
 func (d *dockerImageDestination) SupportedManifestMIMETypes() []string {
 	return []string{
 		// TODO(runcom): we'll add OCI as part of another PR here
@@ -44,42 +48,12 @@ func (d *dockerImageDestination) SupportedManifestMIMETypes() []string {
 	}
 }
 
-func (d *dockerImageDestination) PutManifest(m []byte) error {
-	// FIXME: This only allows upload by digest, not creating a tag.  See the
-	// corresponding comment in openshift.NewImageDestination.
-	digest, err := manifest.Digest(m)
-	if err != nil {
-		return err
-	}
-	url := fmt.Sprintf(manifestURL, d.ref.ref.RemoteName(), digest)
-
-	headers := map[string][]string{}
-	mimeType := manifest.GuessMIMEType(m)
-	if mimeType != "" {
-		headers["Content-Type"] = []string{mimeType}
-	}
-	res, err := d.c.makeRequest("PUT", url, headers, bytes.NewReader(m))
-	if err != nil {
-		return err
-	}
-	defer res.Body.Close()
-	if res.StatusCode != http.StatusCreated {
-		body, err := ioutil.ReadAll(res.Body)
-		if err == nil {
-			logrus.Debugf("Error body %s", string(body))
-		}
-		logrus.Debugf("Error uploading manifest, status %d, %#v", res.StatusCode, res)
-		return fmt.Errorf("Error uploading manifest to %s, status %d", url, res.StatusCode)
-	}
-	return nil
-}
-
 // PutBlob writes contents of stream as a blob identified by digest.
+// The length of stream is expected to be expectedSize; if expectedSize == -1, it is not known.
 // WARNING: The contents of stream are being verified on the fly.  Until stream.Read() returns io.EOF, the contents of the data SHOULD NOT be available
 // to any other readers for download using the supplied digest.
 // If stream.Read() at any time, ESPECIALLY at end of input, returns an error, PutBlob MUST 1) fail, and 2) delete any data stored so far.
-// Note: Calling PutBlob() and other methods may have ordering dependencies WRT other methods of this type. FIXME: Figure out and document.
-func (d *dockerImageDestination) PutBlob(digest string, stream io.Reader) error {
+func (d *dockerImageDestination) PutBlob(digest string, expectedSize int64, stream io.Reader) error {
 	checkURL := fmt.Sprintf(blobsURL, d.ref.ref.RemoteName(), digest)
 
 	logrus.Debugf("Checking %s", checkURL)
@@ -116,7 +90,7 @@ func (d *dockerImageDestination) PutBlob(digest string, stream io.Reader) error
 	locationQuery := uploadLocation.Query()
 	locationQuery.Set("digest", digest)
 	uploadLocation.RawQuery = locationQuery.Encode()
-	res, err = d.c.makeRequestToResolvedURL("PUT", uploadLocation.String(), map[string][]string{"Content-Type": {"application/octet-stream"}}, stream)
+	res, err = d.c.makeRequestToResolvedURL("PUT", uploadLocation.String(), map[string][]string{"Content-Type": {"application/octet-stream"}}, stream, expectedSize)
 	if err != nil {
 		return err
 	}
@@ -130,9 +104,47 @@ func (d *dockerImageDestination) PutBlob(digest string, stream io.Reader) error
 	return nil
 }
 
+func (d *dockerImageDestination) PutManifest(m []byte) error {
+	// FIXME: This only allows upload by digest, not creating a tag.  See the
+	// corresponding comment in openshift.NewImageDestination.
+	digest, err := manifest.Digest(m)
+	if err != nil {
+		return err
+	}
+	url := fmt.Sprintf(manifestURL, d.ref.ref.RemoteName(), digest)
+
+	headers := map[string][]string{}
+	mimeType := manifest.GuessMIMEType(m)
+	if mimeType != "" {
+		headers["Content-Type"] = []string{mimeType}
+	}
+	res, err := d.c.makeRequest("PUT", url, headers, bytes.NewReader(m))
+	if err != nil {
+		return err
+	}
+	defer res.Body.Close()
+	if res.StatusCode != http.StatusCreated {
+		body, err := ioutil.ReadAll(res.Body)
+		if err == nil {
+			logrus.Debugf("Error body %s", string(body))
+		}
+		logrus.Debugf("Error uploading manifest, status %d, %#v", res.StatusCode, res)
+		return fmt.Errorf("Error uploading manifest to %s, status %d", url, res.StatusCode)
+	}
+	return nil
+}
+
 func (d *dockerImageDestination) PutSignatures(signatures [][]byte) error {
 	if len(signatures) != 0 {
 		return fmt.Errorf("Pushing signatures to a Docker Registry is not supported")
 	}
 	return nil
 }
+
+// Commit marks the process of storing the image as successful and asks for the image to be persisted.
+// WARNING: This does not have any transactional semantics:
+// - Uploaded data MAY be visible to others before Commit() is called
+// - Uploaded data MAY be removed or MAY remain around if Close() is called without Commit() (i.e. rollback is allowed but not guaranteed)
+func (d *dockerImageDestination) Commit() error {
+	return nil
+}

vendor/github.com/containers/image/docker/docker_image_src.go

@@ -29,8 +29,9 @@ type dockerImageSource struct {
 }
 
 // newImageSource creates a new ImageSource for the specified image reference,
-// asking the backend to use a manifest from requestedManifestMIMETypes if possible
+// asking the backend to use a manifest from requestedManifestMIMETypes if possible.
 // nil requestedManifestMIMETypes means manifest.DefaultRequestedManifestMIMETypes.
+// The caller must call .Close() on the returned ImageSource.
 func newImageSource(ctx *types.SystemContext, ref dockerReference, requestedManifestMIMETypes []string) (*dockerImageSource, error) {
 	c, err := newDockerClient(ctx, ref.ref.Hostname())
 	if err != nil {
@@ -52,6 +53,10 @@ func (s *dockerImageSource) Reference() types.ImageReference {
 	return s.ref
 }
 
+// Close removes resources associated with an initialized ImageSource, if any.
+func (s *dockerImageSource) Close() {
+}
+
 // simplifyContentType drops parameters from a HTTP media type (see https://tools.ietf.org/html/rfc7231#section-3.1.1.1)
 // Alternatively, an empty string is returned unchanged, and invalid values are "simplified" to an empty string.
 func simplifyContentType(contentType string) string {
@@ -91,6 +96,7 @@ func (s *dockerImageSource) GetManifest() ([]byte, string, error) {
 	return manblob, simplifyContentType(res.Header.Get("Content-Type")), nil
 }
 
+// GetBlob returns a stream for the specified blob, and the blob’s size (or -1 if unknown).
 func (s *dockerImageSource) GetBlob(digest string) (io.ReadCloser, int64, error) {
 	url := fmt.Sprintf(blobsURL, s.ref.ref.RemoteName(), digest)
 	logrus.Debugf("Downloading %s", url)
@@ -104,7 +110,7 @@ func (s *dockerImageSource) GetBlob(digest string) (io.ReadCloser, int64, error)
 	}
 	size, err := strconv.ParseInt(res.Header.Get("Content-Length"), 10, 64)
 	if err != nil {
-		size = 0
+		size = -1
 	}
 	return res.Body, size, nil
 }

vendor/github.com/containers/image/docker/docker_transport.go

@@ -116,18 +116,21 @@ func (ref dockerReference) PolicyConfigurationNamespaces() []string {
 }
 
 // NewImage returns a types.Image for this reference.
+// The caller must call .Close() on the returned Image.
 func (ref dockerReference) NewImage(ctx *types.SystemContext) (types.Image, error) {
 	return newImage(ctx, ref)
 }
 
 // NewImageSource returns a types.ImageSource for this reference,
-// asking the backend to use a manifest from requestedManifestMIMETypes if possible
+// asking the backend to use a manifest from requestedManifestMIMETypes if possible.
 // nil requestedManifestMIMETypes means manifest.DefaultRequestedManifestMIMETypes.
+// The caller must call .Close() on the returned ImageSource.
 func (ref dockerReference) NewImageSource(ctx *types.SystemContext, requestedManifestMIMETypes []string) (types.ImageSource, error) {
 	return newImageSource(ctx, ref, requestedManifestMIMETypes)
 }
 
 // NewImageDestination returns a types.ImageDestination for this reference.
+// The caller must call .Close() on the returned ImageDestination.
 func (ref dockerReference) NewImageDestination(ctx *types.SystemContext) (types.ImageDestination, error) {
 	return newImageDestination(ctx, ref)
 }

vendor/github.com/containers/image/image/image.go

@@ -37,6 +37,12 @@ type genericImage struct {
 }
 
 // FromSource returns a types.Image implementation for source.
+// The caller must call .Close() on the returned Image.
+//
+// FromSource “takes ownership” of the input ImageSource and will call src.Close()
+// when the image is closed.  (This does not prevent callers from using both the
+// Image and ImageSource objects simultaneously, but it means that they only need to
+// the Image.)
 func FromSource(src types.ImageSource) types.Image {
 	return &genericImage{src: src}
 }
@@ -47,6 +53,11 @@ func (i *genericImage) Reference() types.ImageReference {
 	return i.src.Reference()
 }
 
+// Close removes resources associated with an initialized Image, if any.
+func (i *genericImage) Close() {
+	i.src.Close()
+}
+
 // Manifest is like ImageSource.GetManifest, but the result is cached; it is OK to call this however often you need.
 // NOTE: It is essential for signature verification that Manifest returns the manifest from which BlobDigests is computed.
 func (i *genericImage) Manifest() ([]byte, string, error) {

vendor/github.com/containers/image/manifest/manifest.go

@@ -28,9 +28,9 @@ const (
 	// OCIV1ImageManifestListMIMEType specifies the mediaType for an image manifest list.
 	OCIV1ImageManifestListMIMEType = "application/vnd.oci.image.manifest.list.v1+json"
 	// OCIV1ImageSerializationMIMEType is the mediaType used for layers referenced by the manifest.
-	OCIV1ImageSerializationMIMEType = "application/vnd.oci.image.serialization.rootfs.tar.gzip"
+	OCIV1ImageSerializationMIMEType = "application/vnd.oci.image.layer.tar+gzip"
 	// OCIV1ImageSerializationConfigMIMEType specifies the mediaType for the image configuration.
-	OCIV1ImageSerializationConfigMIMEType = "application/vnd.oci.image.serialization.config.v1+json"
+	OCIV1ImageSerializationConfigMIMEType = "application/vnd.oci.image.config.v1+json"
 )
 
 // DefaultRequestedManifestMIMETypes is a list of MIME types a types.ImageSource

vendor/github.com/containers/image/oci/oci_dest.go

@@ -41,6 +41,55 @@ func (d *ociImageDestination) Reference() types.ImageReference {
 	return d.ref
 }
 
+// Close removes resources associated with an initialized ImageDestination, if any.
+func (d *ociImageDestination) Close() {
+}
+
+// PutBlob writes contents of stream as a blob identified by digest.
+// The length of stream is expected to be expectedSize; if expectedSize == -1, it is not known.
+// WARNING: The contents of stream are being verified on the fly.  Until stream.Read() returns io.EOF, the contents of the data SHOULD NOT be available
+// to any other readers for download using the supplied digest.
+// If stream.Read() at any time, ESPECIALLY at end of input, returns an error, PutBlob MUST 1) fail, and 2) delete any data stored so far.
+func (d *ociImageDestination) PutBlob(digest string, expectedSize int64, stream io.Reader) error {
+	blobPath, err := d.ref.blobPath(digest)
+	if err != nil {
+		return err
+	}
+	if err := ensureParentDirectoryExists(blobPath); err != nil {
+		return err
+	}
+	blobFile, err := ioutil.TempFile(filepath.Dir(blobPath), filepath.Base(blobPath))
+	if err != nil {
+		return err
+	}
+	succeeded := false
+	defer func() {
+		blobFile.Close()
+		if !succeeded {
+			os.Remove(blobFile.Name())
+		}
+	}()
+
+	size, err := io.Copy(blobFile, stream)
+	if err != nil {
+		return err
+	}
+	if expectedSize != -1 && size != expectedSize {
+		return fmt.Errorf("Size mismatch when copying %s, expected %d, got %d", digest, expectedSize, size)
+	}
+	if err := blobFile.Sync(); err != nil {
+		return err
+	}
+	if err := blobFile.Chmod(0644); err != nil {
+		return err
+	}
+	if err := os.Rename(blobFile.Name(), blobPath); err != nil {
+		return nil
+	}
+	succeeded = true
+	return nil
+}
+
 func createManifest(m []byte) ([]byte, string, error) {
 	om := ociManifest{}
 	mt := manifest.GuessMIMEType(m)
@@ -114,47 +163,6 @@ func (d *ociImageDestination) PutManifest(m []byte) error {
 	return ioutil.WriteFile(descriptorPath, data, 0644)
 }
 
-// PutBlob writes contents of stream as a blob identified by digest.
-// WARNING: The contents of stream are being verified on the fly.  Until stream.Read() returns io.EOF, the contents of the data SHOULD NOT be available
-// to any other readers for download using the supplied digest.
-// If stream.Read() at any time, ESPECIALLY at end of input, returns an error, PutBlob MUST 1) fail, and 2) delete any data stored so far.
-// Note: Calling PutBlob() and other methods may have ordering dependencies WRT other methods of this type. FIXME: Figure out and document.
-func (d *ociImageDestination) PutBlob(digest string, stream io.Reader) error {
-	blobPath, err := d.ref.blobPath(digest)
-	if err != nil {
-		return err
-	}
-	if err := ensureParentDirectoryExists(blobPath); err != nil {
-		return err
-	}
-	blobFile, err := ioutil.TempFile(filepath.Dir(blobPath), filepath.Base(blobPath))
-	if err != nil {
-		return err
-	}
-	succeeded := false
-	defer func() {
-		blobFile.Close()
-		if !succeeded {
-			os.Remove(blobFile.Name())
-		}
-	}()
-
-	if _, err := io.Copy(blobFile, stream); err != nil {
-		return err
-	}
-	if err := blobFile.Sync(); err != nil {
-		return err
-	}
-	if err := blobFile.Chmod(0644); err != nil {
-		return err
-	}
-	if err := os.Rename(blobFile.Name(), blobPath); err != nil {
-		return nil
-	}
-	succeeded = true
-	return nil
-}
-
 // ensureParentDirectoryExists ensures the parent of the supplied path exists.
 func ensureParentDirectoryExists(path string) error {
 	parent := filepath.Dir(path)
@@ -179,3 +187,11 @@ func (d *ociImageDestination) PutSignatures(signatures [][]byte) error {
 	}
 	return nil
 }
+
+// Commit marks the process of storing the image as successful and asks for the image to be persisted.
+// WARNING: This does not have any transactional semantics:
+// - Uploaded data MAY be visible to others before Commit() is called
+// - Uploaded data MAY be removed or MAY remain around if Close() is called without Commit() (i.e. rollback is allowed but not guaranteed)
+func (d *ociImageDestination) Commit() error {
+	return nil
+}

vendor/github.com/containers/image/oci/oci_transport.go

@@ -165,18 +165,21 @@ func (ref ociReference) PolicyConfigurationNamespaces() []string {
 }
 
 // NewImage returns a types.Image for this reference.
+// The caller must call .Close() on the returned Image.
 func (ref ociReference) NewImage(ctx *types.SystemContext) (types.Image, error) {
 	return nil, errors.New("Full Image support not implemented for oci: image names")
 }
 
 // NewImageSource returns a types.ImageSource for this reference,
-// asking the backend to use a manifest from requestedManifestMIMETypes if possible
+// asking the backend to use a manifest from requestedManifestMIMETypes if possible.
 // nil requestedManifestMIMETypes means manifest.DefaultRequestedManifestMIMETypes.
+// The caller must call .Close() on the returned ImageSource.
 func (ref ociReference) NewImageSource(ctx *types.SystemContext, requestedManifestMIMETypes []string) (types.ImageSource, error) {
 	return nil, errors.New("Reading images not implemented for oci: image names")
 }
 
 // NewImageDestination returns a types.ImageDestination for this reference.
+// The caller must call .Close() on the returned ImageDestination.
 func (ref ociReference) NewImageDestination(ctx *types.SystemContext) (types.ImageDestination, error) {
 	return newImageDestination(ref), nil
 }

vendor/github.com/containers/image/openshift/openshift.go

@@ -179,8 +179,9 @@ type openshiftImageSource struct {
 }
 
 // newImageSource creates a new ImageSource for the specified reference,
-// asking the backend to use a manifest from requestedManifestMIMETypes if possible
+// asking the backend to use a manifest from requestedManifestMIMETypes if possible.
 // nil requestedManifestMIMETypes means manifest.DefaultRequestedManifestMIMETypes.
+// The caller must call .Close() on the returned ImageSource.
 func newImageSource(ctx *types.SystemContext, ref openshiftReference, requestedManifestMIMETypes []string) (types.ImageSource, error) {
 	client, err := newOpenshiftClient(ref)
 	if err != nil {
@@ -200,6 +201,14 @@ func (s *openshiftImageSource) Reference() types.ImageReference {
 	return s.client.ref
 }
 
+// Close removes resources associated with an initialized ImageSource, if any.
+func (s *openshiftImageSource) Close() {
+	if s.docker != nil {
+		s.docker.Close()
+		s.docker = nil
+	}
+}
+
 func (s *openshiftImageSource) GetManifest() ([]byte, string, error) {
 	if err := s.ensureImageIsResolved(); err != nil {
 		return nil, "", err
@@ -207,6 +216,7 @@ func (s *openshiftImageSource) GetManifest() ([]byte, string, error) {
 	return s.docker.GetManifest()
 }
 
+// GetBlob returns a stream for the specified blob, and the blob’s size (or -1 if unknown).
 func (s *openshiftImageSource) GetBlob(digest string) (io.ReadCloser, int64, error) {
 	if err := s.ensureImageIsResolved(); err != nil {
 		return nil, 0, err
@@ -320,6 +330,11 @@ func (d *openshiftImageDestination) Reference() types.ImageReference {
 	return d.client.ref
 }
 
+// Close removes resources associated with an initialized ImageDestination, if any.
+func (d *openshiftImageDestination) Close() {
+	d.docker.Close()
+}
+
 func (d *openshiftImageDestination) SupportedManifestMIMETypes() []string {
 	return []string{
 		manifest.DockerV2Schema1SignedMIMEType,
@@ -327,6 +342,15 @@ func (d *openshiftImageDestination) SupportedManifestMIMETypes() []string {
 	}
 }
 
+// PutBlob writes contents of stream as a blob identified by digest.
+// The length of stream is expected to be expectedSize; if expectedSize == -1, it is not known.
+// WARNING: The contents of stream are being verified on the fly.  Until stream.Read() returns io.EOF, the contents of the data SHOULD NOT be available
+// to any other readers for download using the supplied digest.
+// If stream.Read() at any time, ESPECIALLY at end of input, returns an error, PutBlob MUST 1) fail, and 2) delete any data stored so far.
+func (d *openshiftImageDestination) PutBlob(digest string, expectedSize int64, stream io.Reader) error {
+	return d.docker.PutBlob(digest, expectedSize, stream)
+}
+
 func (d *openshiftImageDestination) PutManifest(m []byte) error {
 	// FIXME? Can this eventually just call d.docker.PutManifest()?
 	// Right now we need this as a skeleton to attach signatures to, and
@@ -373,19 +397,9 @@ func (d *openshiftImageDestination) PutManifest(m []byte) error {
 	return nil
 }
 
-// PutBlob writes contents of stream as a blob identified by digest.
-// WARNING: The contents of stream are being verified on the fly.  Until stream.Read() returns io.EOF, the contents of the data SHOULD NOT be available
-// to any other readers for download using the supplied digest.
-// If stream.Read() at any time, ESPECIALLY at end of input, returns an error, PutBlob MUST 1) fail, and 2) delete any data stored so far.
-// Note: Calling PutBlob() and other methods may have ordering dependencies WRT other methods of this type. FIXME: Figure out and document.
-func (d *openshiftImageDestination) PutBlob(digest string, stream io.Reader) error {
-	return d.docker.PutBlob(digest, stream)
-}
-
 func (d *openshiftImageDestination) PutSignatures(signatures [][]byte) error {
-	// FIXME: This assumption that signatures are stored after the manifest rather breaks the model.
 	if d.imageStreamImageName == "" {
-		return fmt.Errorf("Unknown manifest digest, can't add signatures")
+		return fmt.Errorf("Internal error: Unknown manifest digest, can't add signatures")
 	}
 	// Because image signatures are a shared resource in Atomic Registry, the default upload
 	// always adds signatures.  Eventually we should also allow removing signatures.
@@ -444,6 +458,14 @@ sigExists:
 	return nil
 }
 
+// Commit marks the process of storing the image as successful and asks for the image to be persisted.
+// WARNING: This does not have any transactional semantics:
+// - Uploaded data MAY be visible to others before Commit() is called
+// - Uploaded data MAY be removed or MAY remain around if Close() is called without Commit() (i.e. rollback is allowed but not guaranteed)
+func (d *openshiftImageDestination) Commit() error {
+	return d.docker.Commit()
+}
+
 // These structs are subsets of github.com/openshift/origin/pkg/image/api/v1 and its dependencies.
 type imageStream struct {
 	Status imageStreamStatus `json:"status,omitempty"`

vendor/github.com/containers/image/openshift/openshift_transport.go

@@ -154,18 +154,21 @@ func (ref openshiftReference) PolicyConfigurationNamespaces() []string {
 }
 
 // NewImage returns a types.Image for this reference.
+// The caller must call .Close() on the returned Image.
 func (ref openshiftReference) NewImage(ctx *types.SystemContext) (types.Image, error) {
 	return nil, errors.New("Full Image support not implemented for atomic: image names")
 }
 
 // NewImageSource returns a types.ImageSource for this reference,
-// asking the backend to use a manifest from requestedManifestMIMETypes if possible
+// asking the backend to use a manifest from requestedManifestMIMETypes if possible.
 // nil requestedManifestMIMETypes means manifest.DefaultRequestedManifestMIMETypes.
+// The caller must call .Close() on the returned ImageSource.
 func (ref openshiftReference) NewImageSource(ctx *types.SystemContext, requestedManifestMIMETypes []string) (types.ImageSource, error) {
 	return newImageSource(ctx, ref, requestedManifestMIMETypes)
 }
 
 // NewImageDestination returns a types.ImageDestination for this reference.
+// The caller must call .Close() on the returned ImageDestination.
 func (ref openshiftReference) NewImageDestination(ctx *types.SystemContext) (types.ImageDestination, error) {
 	return newImageDestination(ctx, ref)
 }

vendor/github.com/containers/image/types/types.go

@@ -71,12 +71,15 @@ type ImageReference interface {
 	PolicyConfigurationNamespaces() []string
 
 	// NewImage returns a types.Image for this reference.
+	// The caller must call .Close() on the returned Image.
 	NewImage(ctx *SystemContext) (Image, error)
 	// NewImageSource returns a types.ImageSource for this reference,
-	// asking the backend to use a manifest from requestedManifestMIMETypes if possible
+	// asking the backend to use a manifest from requestedManifestMIMETypes if possible.
 	// nil requestedManifestMIMETypes means manifest.DefaultRequestedManifestMIMETypes.
+	// The caller must call .Close() on the returned ImageSource.
 	NewImageSource(ctx *SystemContext, requestedManifestMIMETypes []string) (ImageSource, error)
 	// NewImageDestination returns a types.ImageDestination for this reference.
+	// The caller must call .Close() on the returned ImageDestination.
 	NewImageDestination(ctx *SystemContext) (ImageDestination, error)
 
 	// DeleteImage deletes the named image from the registry, if supported.
@@ -86,44 +89,63 @@ type ImageReference interface {
 // ImageSource is a service, possibly remote (= slow), to download components of a single image.
 // This is primarily useful for copying images around; for examining their properties, Image (below)
 // is usually more useful.
+// Each ImageSource should eventually be closed by calling Close().
 type ImageSource interface {
 	// Reference returns the reference used to set up this source, _as specified by the user_
 	// (not as the image itself, or its underlying storage, claims).  This can be used e.g. to determine which public keys are trusted for this image.
 	Reference() ImageReference
+	// Close removes resources associated with an initialized ImageSource, if any.
+	Close()
 	// GetManifest returns the image's manifest along with its MIME type. The empty string is returned if the MIME type is unknown.
 	// It may use a remote (= slow) service.
 	GetManifest() ([]byte, string, error)
-	// Note: Calling GetBlob() may have ordering dependencies WRT other methods of this type. FIXME: How does this work with (docker save) on stdin?
-	// the second return value is the size of the blob. If not known 0 is returned
+	// GetBlob returns a stream for the specified blob, and the blob’s size (or -1 if unknown).
 	GetBlob(digest string) (io.ReadCloser, int64, error)
 	// GetSignatures returns the image's signatures.  It may use a remote (= slow) service.
 	GetSignatures() ([][]byte, error)
 }
 
 // ImageDestination is a service, possibly remote (= slow), to store components of a single image.
+//
+// There is a specific required order for some of the calls:
+// PutBlob on the various blobs, if any, MUST be called before PutManifest (manifest references blobs, which may be created or compressed only at push time)
+// PutSignatures, if called, MUST be called after PutManifest (signatures reference manifest contents)
+// Finally, Commit MUST be called if the caller wants the image, as formed by the components saved above, to persist.
+//
+// Each ImageDestination should eventually be closed by calling Close().
 type ImageDestination interface {
 	// Reference returns the reference used to set up this destination.  Note that this should directly correspond to user's intent,
 	// e.g. it should use the public hostname instead of the result of resolving CNAMEs or following redirects.
 	Reference() ImageReference
-	// FIXME? This should also receive a MIME type if known, to differentiate between schema versions.
-	PutManifest([]byte) error
+	// Close removes resources associated with an initialized ImageDestination, if any.
+	Close()
 	// PutBlob writes contents of stream as a blob identified by digest.
+	// The length of stream is expected to be expectedSize; if expectedSize == -1, it is not known.
 	// WARNING: The contents of stream are being verified on the fly.  Until stream.Read() returns io.EOF, the contents of the data SHOULD NOT be available
 	// to any other readers for download using the supplied digest.
 	// If stream.Read() at any time, ESPECIALLY at end of input, returns an error, PutBlob MUST 1) fail, and 2) delete any data stored so far.
-	// Note: Calling PutBlob() and other methods may have ordering dependencies WRT other methods of this type. FIXME: Figure out and document.
-	PutBlob(digest string, stream io.Reader) error
+	PutBlob(digest string, expectedSize int64, stream io.Reader) error
+	// FIXME? This should also receive a MIME type if known, to differentiate between schema versions.
+	PutManifest([]byte) error
 	PutSignatures(signatures [][]byte) error
+	// Commit marks the process of storing the image as successful and asks for the image to be persisted.
+	// WARNING: This does not have any transactional semantics:
+	// - Uploaded data MAY be visible to others before Commit() is called
+	// - Uploaded data MAY be removed or MAY remain around if Close() is called without Commit() (i.e. rollback is allowed but not guaranteed)
+	Commit() error
 	// SupportedManifestMIMETypes tells which manifest mime types the destination supports
 	// If an empty slice or nil it's returned, then any mime type can be tried to upload
 	SupportedManifestMIMETypes() []string
 }
 
 // Image is the primary API for inspecting properties of images.
+// Each Image should eventually be closed by calling Close().
 type Image interface {
 	// Reference returns the reference used to set up this source, _as specified by the user_
 	// (not as the image itself, or its underlying storage, claims).  This can be used e.g. to determine which public keys are trusted for this image.
 	Reference() ImageReference
+	// Close removes resources associated with an initialized Image, if any.
+	Close()
 	// ref to repository?
 	// Manifest is like ImageSource.GetManifest, but the result is cached; it is OK to call this however often you need.
 	// NOTE: It is essential for signature verification that Manifest returns the manifest from which BlobDigests is computed.