compute image VirtualSize

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

daemon/containerd/image_list.go

@@ -3,7 +3,10 @@ package containerd
 import (
 	"context"
 
+	"github.com/containerd/containerd"
+	"github.com/containerd/containerd/snapshots"
 	"github.com/docker/docker/api/types"
+	"github.com/opencontainers/image-spec/identity"
 )
 
 // Images returns a filtered list of images.
@@ -13,6 +16,8 @@ func (i *ImageService) Images(ctx context.Context, opts types.ImageListOptions)
 		return nil, err
 	}
 
+	snapshotter := i.client.SnapshotService(containerd.DefaultSnapshotter)
+
 	var ret []*types.ImageSummary
 	for _, img := range imgs {
 		size, err := img.Size(ctx)
@@ -20,13 +25,18 @@ func (i *ImageService) Images(ctx context.Context, opts types.ImageListOptions)
 			return nil, err
 		}
 
+		virtualSize, err := computeVirtualSize(ctx, img, snapshotter)
+		if err != nil {
+			return nil, err
+		}
+
 		ret = append(ret, &types.ImageSummary{
 			RepoDigests: []string{img.Name() + "@" + img.Target().Digest.String()}, // "hello-world@sha256:bfea6278a0a267fad2634554f4f0c6f31981eea41c553fdf5a83e95a41d40c38"},
 			RepoTags:    []string{img.Name()},
 			Containers:  -1,
 			ParentID:    "",
 			SharedSize:  -1,
-			VirtualSize: 10,
+			VirtualSize: virtualSize,
 			ID:          img.Target().Digest.String(),
 			Created:     img.Metadata().CreatedAt.Unix(),
 			Size:        size,
@@ -35,3 +45,19 @@ func (i *ImageService) Images(ctx context.Context, opts types.ImageListOptions)
 
 	return ret, nil
 }
+
+func computeVirtualSize(ctx context.Context, image containerd.Image, snapshotter snapshots.Snapshotter) (int64, error) {
+	var virtualSize int64
+	diffIDs, err := image.RootFS(ctx)
+	if err != nil {
+		return virtualSize, err
+	}
+	for _, chainID := range identity.ChainIDs(diffIDs) {
+		usage, err := snapshotter.Usage(ctx, chainID.String())
+		if err != nil {
+			return virtualSize, err
+		}
+		virtualSize += usage.Size
+	}
+	return virtualSize, nil
+}