cache/remotecache: normalize cache layer media types

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>

Author: crazy-max

cache/remotecache/v1/chains_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/containerd/containerd/v2/core/images"
 	"github.com/moby/buildkit/solver"
 	digest "github.com/opencontainers/go-digest"
 	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
@@ -105,6 +106,60 @@ func TestSimpleMarshal(t *testing.T) {
 	require.Equal(t, 4, len(cfg.Records))
 }
 
+func TestMarshalLayerMediaTypes(t *testing.T) {
+	for _, tc := range []struct {
+		name     string
+		descs    []ocispecs.Descriptor
+		expected map[digest.Digest]string
+	}{
+		{
+			name: "docker",
+			descs: []ocispecs.Descriptor{
+				{Digest: dgst("d0"), MediaType: images.MediaTypeDockerSchema2Layer},
+				{Digest: dgst("d1"), MediaType: images.MediaTypeDockerSchema2LayerGzip},
+				{Digest: dgst("d2"), MediaType: images.MediaTypeDockerSchema2LayerZstd},
+			},
+			expected: map[digest.Digest]string{
+				dgst("d0"): ocispecs.MediaTypeImageLayer,
+				dgst("d1"): ocispecs.MediaTypeImageLayerGzip,
+				dgst("d2"): ocispecs.MediaTypeImageLayerZstd,
+			},
+		},
+		{
+			name: "oci",
+			descs: []ocispecs.Descriptor{
+				{Digest: dgst("d0"), MediaType: ocispecs.MediaTypeImageLayer},
+				{Digest: dgst("d1"), MediaType: ocispecs.MediaTypeImageLayerGzip},
+				{Digest: dgst("d2"), MediaType: ocispecs.MediaTypeImageLayerZstd},
+			},
+			expected: map[digest.Digest]string{
+				dgst("d0"): ocispecs.MediaTypeImageLayer,
+				dgst("d1"): ocispecs.MediaTypeImageLayerGzip,
+				dgst("d2"): ocispecs.MediaTypeImageLayerZstd,
+			},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			cc := NewCacheChains()
+			_, ok, err := cc.Add(outputKey(dgst("foo"), 0), nil, []solver.CacheExportResult{{
+				CreatedAt: time.Now(),
+				Result: &solver.Remote{
+					Descriptors: tc.descs,
+				},
+			}})
+			require.NoError(t, err)
+			require.True(t, ok)
+
+			_, descPairs, err := cc.Marshal(t.Context())
+			require.NoError(t, err)
+
+			for dgst, mediaType := range tc.expected {
+				require.Equal(t, mediaType, descPairs[dgst].Descriptor.MediaType)
+			}
+		})
+	}
+}
+
 func dgst(s string) digest.Digest {
 	return digest.FromBytes([]byte(s))
 }

cache/remotecache/v1/utils.go

@@ -10,6 +10,7 @@ import (
 	cerrdefs "github.com/containerd/errdefs"
 	cacheimporttypes "github.com/moby/buildkit/cache/remotecache/v1/types"
 	"github.com/moby/buildkit/solver"
+	"github.com/moby/buildkit/util/compression"
 	digest "github.com/opencontainers/go-digest"
 	"github.com/pkg/errors"
 )
@@ -152,6 +153,9 @@ func marshalRemote(ctx context.Context, r *solver.Remote, state *marshalState) s
 		parentID = marshalRemote(ctx, r2, state)
 	}
 	desc := r.Descriptors[len(r.Descriptors)-1]
+	if desc.MediaType != "" {
+		desc = compression.ConvertAllLayerMediaTypes(ctx, true, desc)[0]
+	}
 
 	state.descriptors[desc.Digest] = DescriptorProviderPair{
 		Descriptor: desc,