containerd: Implement push

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

daemon/containerd/service.go

@@ -11,6 +11,7 @@ import (
 	"github.com/containerd/containerd/content"
 	cerrdefs "github.com/containerd/containerd/errdefs"
 	containerdimages "github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/images/converter"
 	"github.com/containerd/containerd/platforms"
 	"github.com/containerd/containerd/remotes"
 	"github.com/containerd/containerd/remotes/docker"
@@ -357,7 +358,59 @@ func (cs *containerdStore) LookupImage(ctx context.Context, name string) (*types
 }
 
 func (cs *containerdStore) PushImage(ctx context.Context, image, tag string, metaHeaders map[string][]string, authConfig *types.AuthConfig, outStream io.Writer) error {
-	panic("not implemented")
+	// TODO: Pass this from user?
+	platformMatcher := platforms.DefaultStrict()
+
+	ref, err := reference.ParseNormalizedNamed(image)
+	if err != nil {
+		return err
+	}
+	if tag != "" {
+		// Push by digest is not supported, so only tags are supported.
+		ref, err = reference.WithTag(ref, tag)
+		if err != nil {
+			return err
+		}
+	}
+
+	is := cs.client.ImageService()
+
+	img, err := is.Get(ctx, ref.String())
+	if err != nil {
+		return errors.Wrap(err, "Failed to get image")
+	}
+
+	target := img.Target
+
+	// Create a temporary image which is stripped from content that references other platforms.
+	// We or the remote may not have them and referencing them will end with an error.
+	if platformMatcher != platforms.All {
+		tmpRef := ref.String() + "-tmp-platformspecific"
+		platformImg, err := converter.Convert(ctx, cs.client, tmpRef, ref.String(), converter.WithPlatform(platformMatcher))
+		if err != nil {
+			return errors.Wrap(err, "Failed to convert image to platform specific")
+		}
+
+		target = platformImg.Target
+		defer cs.client.ImageService().Delete(ctx, platformImg.Name, containerdimages.SynchronousDelete())
+	}
+
+	imageHandler := containerdimages.HandlerFunc(func(ctx context.Context, desc ocispec.Descriptor) (subdescs []ocispec.Descriptor, err error) {
+		logrus.WithField("desc", desc).Debug("Pushing")
+		return nil, nil
+	})
+	imageHandler = remotes.SkipNonDistributableBlobs(imageHandler)
+
+	resolver := newResolverFromAuthConfig(authConfig)
+
+	logrus.WithField("desc", target).WithField("ref", ref.String()).Info("Pushing desc to remote ref")
+	err = cs.client.Push(ctx, ref.String(), target,
+		containerd.WithResolver(resolver),
+		containerd.WithPlatformMatcher(platformMatcher),
+		containerd.WithImageHandler(imageHandler),
+	)
+
+	return err
 }
 
 func (cs *containerdStore) SearchRegistryForImages(ctx context.Context, searchFilters filters.Args, term string, limit int, authConfig *types.AuthConfig, metaHeaders map[string][]string) (*registrytypes.SearchResults, error) {