bugfix: unpack should always set the snapshot gc label

Wei Fu · fuweid · commit 88401ba68aff · 2019-03-11T16:58:50.000+08:00
There are two images, A and B. A is based on B. If user pulls A first, then user pulls B. containerd already has the unpacked snapshots in the backend. During unpacking B, the client doesn't set gc snapshot reference label to the config descriptor. That is the problem. The gc module cannot reach the snapshot from the config descriptor. If user removes the image B, the snapshot will be deleted by gc module. That is why we should always set the snapshot gc label to config descriptor. Signed-off-by: Wei Fu <fhfuwei@163.com> (cherry picked from commit 2d96aad) Signed-off-by: Wei Fu <fuweid89@gmail.com>
diff --git a/image.go b/image.go
@@ -170,26 +170,22 @@ func (i *image) Unpack(ctx context.Context, snapshotterName string) error {
 		chain = append(chain, layer.Diff.Digest)
 	}
 
-	if unpacked {
-		desc, err := i.i.Config(ctx, cs, i.platform)
-		if err != nil {
-			return err
-		}
+	desc, err := i.i.Config(ctx, cs, i.platform)
+	if err != nil {
+		return err
+	}
 
-		rootfs := identity.ChainID(chain).String()
+	rootfs := identity.ChainID(chain).String()
 
-		cinfo := content.Info{
-			Digest: desc.Digest,
-			Labels: map[string]string{
-				fmt.Sprintf("containerd.io/gc.ref.snapshot.%s", snapshotterName): rootfs,
-			},
-		}
-		if _, err := cs.Update(ctx, cinfo, fmt.Sprintf("labels.containerd.io/gc.ref.snapshot.%s", snapshotterName)); err != nil {
-			return err
-		}
+	cinfo := content.Info{
+		Digest: desc.Digest,
+		Labels: map[string]string{
+			fmt.Sprintf("containerd.io/gc.ref.snapshot.%s", snapshotterName): rootfs,
+		},
 	}
 
-	return nil
+	_, err = cs.Update(ctx, cinfo, fmt.Sprintf("labels.containerd.io/gc.ref.snapshot.%s", snapshotterName))
+	return err
 }
 
 func (i *image) getLayers(ctx context.Context, platform platforms.MatchComparer) ([]rootfs.Layer, error) {
