llbsolver: allow empty returns for opts

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

frontend/dockerfile/dockerfile_test.go

@@ -24,6 +24,7 @@ import (
 	"github.com/containerd/containerd/platforms"
 	"github.com/containerd/continuity/fs/fstest"
 	"github.com/moby/buildkit/client"
+	"github.com/moby/buildkit/client/llb"
 	"github.com/moby/buildkit/frontend/dockerfile/builder"
 	"github.com/moby/buildkit/identity"
 	"github.com/moby/buildkit/util/testutil/httpserver"
@@ -60,9 +61,132 @@ func TestIntegration(t *testing.T) {
 		testNoCache,
 		testDockerfileFromHTTP,
 		testBuiltinArgs,
+		testPullScratch,
 	})
 }
 
+func testPullScratch(t *testing.T, sb integration.Sandbox) {
+	t.Parallel()
+
+	var cdAddress string
+	if cd, ok := sb.(interface {
+		ContainerdAddress() string
+	}); !ok {
+		t.Skip("requires local image store")
+	} else {
+		cdAddress = cd.ContainerdAddress()
+	}
+
+	dockerfile := []byte(`
+FROM scratch
+LABEL foo=bar
+`)
+
+	dir, err := tmpdir(
+		fstest.CreateFile("Dockerfile", dockerfile, 0600),
+	)
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	c, err := client.New(sb.Address())
+	require.NoError(t, err)
+	defer c.Close()
+
+	target := "docker.io/moby/testpullscratch:latest"
+	_, err = c.Solve(context.TODO(), nil, client.SolveOpt{
+		Frontend: "dockerfile.v0",
+		Exporter: client.ExporterImage,
+		ExporterAttrs: map[string]string{
+			"name": target,
+		},
+		LocalDirs: map[string]string{
+			builder.LocalNameDockerfile: dir,
+			builder.LocalNameContext:    dir,
+		},
+	}, nil)
+	require.NoError(t, err)
+
+	dockerfile = []byte(`
+FROM docker.io/moby/testpullscratch:latest
+LABEL bar=baz
+COPY foo .
+`)
+
+	dir, err = tmpdir(
+		fstest.CreateFile("Dockerfile", dockerfile, 0600),
+		fstest.CreateFile("foo", []byte("foo-contents"), 0600),
+	)
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	target = "docker.io/moby/testpullscratch2:latest"
+	_, err = c.Solve(context.TODO(), nil, client.SolveOpt{
+		Frontend: "dockerfile.v0",
+		Exporter: client.ExporterImage,
+		ExporterAttrs: map[string]string{
+			"name": target,
+		},
+		LocalDirs: map[string]string{
+			builder.LocalNameDockerfile: dir,
+			builder.LocalNameContext:    dir,
+		},
+	}, nil)
+	require.NoError(t, err)
+
+	ctr, err := containerd.New(cdAddress)
+	require.NoError(t, err)
+	defer ctr.Close()
+
+	ctx := namespaces.WithNamespace(context.Background(), "buildkit")
+
+	img, err := ctr.ImageService().Get(ctx, target)
+	require.NoError(t, err)
+
+	desc, err := img.Config(ctx, ctr.ContentStore(), platforms.Default())
+	require.NoError(t, err)
+
+	dt, err := content.ReadBlob(ctx, ctr.ContentStore(), desc.Digest)
+	require.NoError(t, err)
+
+	var ociimg ocispec.Image
+	err = json.Unmarshal(dt, &ociimg)
+	require.NoError(t, err)
+
+	require.Equal(t, "layers", ociimg.RootFS.Type)
+	require.Equal(t, 1, len(ociimg.RootFS.DiffIDs))
+	v, ok := ociimg.Config.Labels["foo"]
+	require.True(t, ok)
+	require.Equal(t, v, "bar")
+	v, ok = ociimg.Config.Labels["bar"]
+	require.True(t, ok)
+	require.Equal(t, v, "baz")
+
+	echo := llb.Image("busybox").
+		Run(llb.Shlex(`sh -c "echo -n foo0 > /empty/foo"`)).
+		AddMount("/empty", llb.Image("docker.io/moby/testpullscratch:latest"))
+
+	def, err := echo.Marshal()
+	require.NoError(t, err)
+
+	destDir, err := ioutil.TempDir("", "buildkit")
+	require.NoError(t, err)
+	defer os.RemoveAll(destDir)
+
+	_, err = c.Solve(context.TODO(), def, client.SolveOpt{
+		Exporter:          client.ExporterLocal,
+		ExporterOutputDir: destDir,
+		LocalDirs: map[string]string{
+			builder.LocalNameDockerfile: dir,
+			builder.LocalNameContext:    dir,
+		},
+	}, nil)
+	require.NoError(t, err)
+
+	dt, err = ioutil.ReadFile(filepath.Join(destDir, "foo"))
+	require.NoError(t, err)
+	require.Equal(t, "foo0", string(dt))
+}
+
 func testGlobalArg(t *testing.T, sb integration.Sandbox) {
 	t.Parallel()
 	dockerfile := []byte(`

solver/llbsolver/result.go

@@ -68,11 +68,13 @@ func (s *cacheResultStorage) Save(res solver.Result) (solver.CacheResult, error)
 	if !ok {
 		return solver.CacheResult{}, errors.Errorf("invalid result: %T", res.Sys())
 	}
-	if !cache.HasCachePolicyRetain(ref.ImmutableRef) {
-		if err := cache.CachePolicyRetain(ref.ImmutableRef); err != nil {
-			return solver.CacheResult{}, err
+	if ref.ImmutableRef != nil {
+		if !cache.HasCachePolicyRetain(ref.ImmutableRef) {
+			if err := cache.CachePolicyRetain(ref.ImmutableRef); err != nil {
+				return solver.CacheResult{}, err
+			}
+			ref.ImmutableRef.Metadata().Commit()
 		}
-		ref.ImmutableRef.Metadata().Commit()
 	}
 	return solver.CacheResult{ID: ref.ID(), CreatedAt: time.Now()}, nil
 }
@@ -97,7 +99,9 @@ func (s *cacheResultStorage) load(id string) (solver.Result, error) {
 	if err != nil {
 		return nil, err
 	}
-
+	if refID == "" {
+		return worker.NewWorkerRefResult(nil, w), nil
+	}
 	ref, err := w.LoadRef(refID)
 	if err != nil {
 		return nil, err

source/containerimage/pull.go

@@ -149,6 +149,9 @@ func (p *puller) Snapshot(ctx context.Context) (cache.ImmutableRef, error) {
 	if err != nil {
 		return nil, err
 	}
+	if pulled.ChainID == "" {
+		return nil, nil
+	}
 	return p.CacheAccessor.GetFromSnapshotter(ctx, string(pulled.ChainID), cache.WithDescription(fmt.Sprintf("pulled from %s", pulled.Ref)))
 }
 

worker/result.go

@@ -17,7 +17,11 @@ type WorkerRef struct {
 }
 
 func (wr *WorkerRef) ID() string {
-	return wr.Worker.ID() + "::" + wr.ImmutableRef.ID()
+	refID := ""
+	if wr.ImmutableRef != nil {
+		refID = wr.ImmutableRef.ID()
+	}
+	return wr.Worker.ID() + "::" + refID
 }
 
 type workerRefResult struct {
@@ -25,6 +29,9 @@ type workerRefResult struct {
 }
 
 func (r *workerRefResult) Release(ctx context.Context) error {
+	if r.ImmutableRef == nil {
+		return nil
+	}
 	return r.ImmutableRef.Release(ctx)
 }