Merge pull request #2801 from hshiina/idmapping

Compute diffID for mapped-layer at creating image source

image.go

@@ -321,10 +321,7 @@ func (i *containerImageRef) NewImageSource(ctx context.Context, sc *types.System
 		}
 		// If we're not re-exporting the data, and we're reusing layers individually, reuse
 		// the blobsum and diff IDs.
-		if !i.exporting && !i.squash && layerID != i.layerID {
-			if layer.UncompressedDigest == "" {
-				return nil, errors.Errorf("unable to look up size of layer %q", layerID)
-			}
+		if !i.exporting && !i.squash && layerID != i.layerID && layer.UncompressedDigest != "" {
 			layerBlobSum := layer.UncompressedDigest
 			layerBlobSize := layer.UncompressedSize
 			diffID := layer.UncompressedDigest

tests/namespaces.bats

@@ -203,6 +203,9 @@ load helpers
     expect_output "$rootuid:$rootgid 4700"
     run_buildah run $RUNOPTS "$ctr" stat -c '%u:%g %a' /somedir/someotherfile
     expect_output "0:0 4700"
+
+    # Check that a container with mapped-layer can be committed.
+    run_buildah commit "$ctr" localhost/alpine-working:$i
   done
 }