ctr: Fixes Windows image import

claudiubelu · claudiubelu · commit 6b0b64a51a51 · 2021-09-02T19:27:28.000-07:00
A previous commit made the Windows containerd/platforms.Default stricter
by requiring the OS Version to have a similar OS Version as the node's OS Version.

However, tar images (from docker save) do not have any OS Version information,
causing the containerd/import.Import's images.FilterPlatforms to filter out the image
entirely, which means that the images.SetChildrenLabels doesn't get to label
any children, which in turn will cause the Garbage Collector to remove content
related to the image.

This sets a default platform for the imported image if it's a Windows image which
doesn't have any OSVersion information, or if there's no platform information at
all.

Signed-off-by: Claudiu Belu &lt;cbelu@cloudbasesolutions.com&gt;
diff --git a/images/archive/importer.go b/images/archive/importer.go
@@ -32,6 +32,7 @@ import (
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/log"
+	"github.com/containerd/containerd/platforms"
 	digest "github.com/opencontainers/go-digest"
 	specs "github.com/opencontainers/image-spec/specs-go"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
@@ -186,15 +187,25 @@ func ImportIndex(ctx context.Context, store content.Store, reader io.Reader, opt
 			return ocispec.Descriptor{}, errors.Wrap(err, "write docker manifest")
 		}
 
-		platforms, err := images.Platforms(ctx, store, desc)
+		imgPlatforms, err := images.Platforms(ctx, store, desc)
 		if err != nil {
 			return ocispec.Descriptor{}, errors.Wrap(err, "unable to resolve platform")
 		}
-		if len(platforms) > 0 {
+		if len(imgPlatforms) > 0 {
 			// Only one platform can be resolved from non-index manifest,
 			// The platform can only come from the config included above,
 			// if the config has no platform it can be safely omitted.
-			desc.Platform = &platforms[0]
+			desc.Platform = &imgPlatforms[0]
+
+			// If the image we've just imported is a Windows image without the OSVersion set,
+			// we could just assume it matches this host's OS Version. Without this, the
+			// children labels might not be set on the image content, leading to it being
+			// garbage collected, breaking the image.
+			// See: https://github.com/containerd/containerd/issues/5690
+			if desc.Platform.OS == "windows" && desc.Platform.OSVersion == "" {
+				platform := platforms.DefaultSpec()
+				desc.Platform.OSVersion = platform.OSVersion
+			}
 		}
 
 		if len(mfst.RepoTags) == 0 {
