exporter: add image exporter

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

api/services/control/control.pb.go

@@ -117,8 +117,10 @@ func (m *UsageRecord) GetSize_() int64 {
 }
 
 type SolveRequest struct {
-	Ref        string   `protobuf:"bytes,1,opt,name=Ref,proto3" json:"Ref,omitempty"`
+	Ref           string            `protobuf:"bytes,1,opt,name=Ref,proto3" json:"Ref,omitempty"`
-	Definition [][]byte `protobuf:"bytes,2,rep,name=Definition" json:"Definition,omitempty"`
+	Definition    [][]byte          `protobuf:"bytes,2,rep,name=Definition" json:"Definition,omitempty"`
+	Exporter      string            `protobuf:"bytes,3,opt,name=Exporter,proto3" json:"Exporter,omitempty"`
+	ExporterAttrs map[string]string `protobuf:"bytes,4,rep,name=ExporterAttrs" json:"ExporterAttrs,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
 }
 
 func (m *SolveRequest) Reset()                    { *m = SolveRequest{} }
@@ -140,6 +142,20 @@ func (m *SolveRequest) GetDefinition() [][]byte {
 	return nil
 }
 
+func (m *SolveRequest) GetExporter() string {
+	if m != nil {
+		return m.Exporter
+	}
+	return ""
+}
+
+func (m *SolveRequest) GetExporterAttrs() map[string]string {
+	if m != nil {
+		return m.ExporterAttrs
+	}
+	return nil
+}
+
 type SolveResponse struct {
 	Vtx []*Vertex `protobuf:"bytes,1,rep,name=vtx" json:"vtx,omitempty"`
 }
@@ -658,6 +674,29 @@ func (m *SolveRequest) MarshalTo(dAtA []byte) (int, error) {
 			i += copy(dAtA[i:], b)
 		}
 	}
+	if len(m.Exporter) > 0 {
+		dAtA[i] = 0x1a
+		i++
+		i = encodeVarintControl(dAtA, i, uint64(len(m.Exporter)))
+		i += copy(dAtA[i:], m.Exporter)
+	}
+	if len(m.ExporterAttrs) > 0 {
+		for k, _ := range m.ExporterAttrs {
+			dAtA[i] = 0x22
+			i++
+			v := m.ExporterAttrs[k]
+			mapSize := 1 + len(k) + sovControl(uint64(len(k))) + 1 + len(v) + sovControl(uint64(len(v)))
+			i = encodeVarintControl(dAtA, i, uint64(mapSize))
+			dAtA[i] = 0xa
+			i++
+			i = encodeVarintControl(dAtA, i, uint64(len(k)))
+			i += copy(dAtA[i:], k)
+			dAtA[i] = 0x12
+			i++
+			i = encodeVarintControl(dAtA, i, uint64(len(v)))
+			i += copy(dAtA[i:], v)
+		}
+	}
 	return i, nil
 }
 
@@ -1044,6 +1083,18 @@ func (m *SolveRequest) Size() (n int) {
 			n += 1 + l + sovControl(uint64(l))
 		}
 	}
+	l = len(m.Exporter)
+	if l > 0 {
+		n += 1 + l + sovControl(uint64(l))
+	}
+	if len(m.ExporterAttrs) > 0 {
+		for k, v := range m.ExporterAttrs {
+			_ = k
+			_ = v
+			mapEntrySize := 1 + len(k) + sovControl(uint64(len(k))) + 1 + len(v) + sovControl(uint64(len(v)))
+			n += mapEntrySize + 1 + sovControl(uint64(mapEntrySize))
+		}
+	}
 	return n
 }
 
@@ -1550,6 +1601,151 @@ func (m *SolveRequest) Unmarshal(dAtA []byte) error {
 			m.Definition = append(m.Definition, make([]byte, postIndex-iNdEx))
 			copy(m.Definition[len(m.Definition)-1], dAtA[iNdEx:postIndex])
 			iNdEx = postIndex
+		case 3:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Exporter", wireType)
+			}
+			var stringLen uint64
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowControl
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				stringLen |= (uint64(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			intStringLen := int(stringLen)
+			if intStringLen < 0 {
+				return ErrInvalidLengthControl
+			}
+			postIndex := iNdEx + intStringLen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Exporter = string(dAtA[iNdEx:postIndex])
+			iNdEx = postIndex
+		case 4:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field ExporterAttrs", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowControl
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLengthControl
+			}
+			postIndex := iNdEx + msglen
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			var keykey uint64
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowControl
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				keykey |= (uint64(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			var stringLenmapkey uint64
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflowControl
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				stringLenmapkey |= (uint64(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			intStringLenmapkey := int(stringLenmapkey)
+			if intStringLenmapkey < 0 {
+				return ErrInvalidLengthControl
+			}
+			postStringIndexmapkey := iNdEx + intStringLenmapkey
+			if postStringIndexmapkey > l {
+				return io.ErrUnexpectedEOF
+			}
+			mapkey := string(dAtA[iNdEx:postStringIndexmapkey])
+			iNdEx = postStringIndexmapkey
+			if m.ExporterAttrs == nil {
+				m.ExporterAttrs = make(map[string]string)
+			}
+			if iNdEx < postIndex {
+				var valuekey uint64
+				for shift := uint(0); ; shift += 7 {
+					if shift >= 64 {
+						return ErrIntOverflowControl
+					}
+					if iNdEx >= l {
+						return io.ErrUnexpectedEOF
+					}
+					b := dAtA[iNdEx]
+					iNdEx++
+					valuekey |= (uint64(b) & 0x7F) << shift
+					if b < 0x80 {
+						break
+					}
+				}
+				var stringLenmapvalue uint64
+				for shift := uint(0); ; shift += 7 {
+					if shift >= 64 {
+						return ErrIntOverflowControl
+					}
+					if iNdEx >= l {
+						return io.ErrUnexpectedEOF
+					}
+					b := dAtA[iNdEx]
+					iNdEx++
+					stringLenmapvalue |= (uint64(b) & 0x7F) << shift
+					if b < 0x80 {
+						break
+					}
+				}
+				intStringLenmapvalue := int(stringLenmapvalue)
+				if intStringLenmapvalue < 0 {
+					return ErrInvalidLengthControl
+				}
+				postStringIndexmapvalue := iNdEx + intStringLenmapvalue
+				if postStringIndexmapvalue > l {
+					return io.ErrUnexpectedEOF
+				}
+				mapvalue := string(dAtA[iNdEx:postStringIndexmapvalue])
+				iNdEx = postStringIndexmapvalue
+				m.ExporterAttrs[mapkey] = mapvalue
+			} else {
+				var mapvalue string
+				m.ExporterAttrs[mapkey] = mapvalue
+			}
+			iNdEx = postIndex
 		default:
 			iNdEx = preIndex
 			skippy, err := skipControl(dAtA[iNdEx:])
@@ -2664,50 +2860,55 @@ var (
 func init() { proto.RegisterFile("control.proto", fileDescriptorControl) }
 
 var fileDescriptorControl = []byte{
-	// 711 bytes of a gzipped FileDescriptorProto
+	// 785 bytes of a gzipped FileDescriptorProto
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-	0x1a, 0xf3, 0xfd, 0x71, 0x0d, 0x19, 0xea, 0x79, 0xb8, 0x4a, 0x8a, 0xb9, 0x5b, 0xb9, 0x0c, 0xb5,
+	0x7f, 0xf4, 0x10, 0x29, 0x1d, 0xf0, 0x97, 0xd0, 0x9c, 0xb1, 0x74, 0x99, 0xd0, 0xc2, 0xdb, 0x79,
-	0x5b, 0x95, 0xa1, 0xfe, 0xdf, 0x65, 0x70, 0xbe, 0x20, 0x68, 0xcc, 0xbb, 0xbc, 0xa4, 0x2e, 0xba,
+	0xa0, 0xf7, 0xb5, 0x4b, 0xd1, 0x7a, 0x94, 0x73, 0xc6, 0xdd, 0xba, 0x6e, 0x3d, 0x65, 0xf8, 0x7f,
-	0xb5, 0xba, 0x7f, 0x28, 0x53, 0xb9, 0x99, 0x32, 0x6b, 0x60, 0x72, 0x91, 0x52, 0x2f, 0x96, 0x35,
+	0x59, 0xd0, 0xae, 0x16, 0x6b, 0x6b, 0xaa, 0x8f, 0xc0, 0xd1, 0xa5, 0xd7, 0x2d, 0xfb, 0x38, 0xa9,
-	0x32, 0x88, 0xb6, 0xf2, 0x7d, 0x12, 0xf3, 0x40, 0x56, 0xa8, 0x45, 0xf2, 0xe3, 0xe0, 0x17, 0x82,
+	0x34, 0xc3, 0x9d, 0x52, 0xb9, 0x50, 0x9f, 0xe5, 0x9c, 0xd3, 0x4c, 0x9a, 0x45, 0x50, 0x9a, 0x45,
-	0xda, 0x6b, 0xf5, 0xa1, 0xc0, 0x7b, 0xd0, 0x98, 0x2f, 0x6b, 0xec, 0x5c, 0x9e, 0xea, 0x8b, 0xdb,
+	0xc2, 0x92, 0xc9, 0x30, 0x51, 0x52, 0xd9, 0x44, 0x1b, 0x78, 0x0c, 0xcd, 0xcd, 0xde, 0x7b, 0x80,
-	0xbd, 0xfd, 0xe8, 0xaf, 0x18, 0xbd, 0x9e, 0xde, 0xc0, 0x92, 0xdc, 0x88, 0xf8, 0x8a, 0xfd, 0x52,
+	0x0c, 0x8d, 0x22, 0x5d, 0x2d, 0xc5, 0xc6, 0xad, 0x5a, 0x86, 0xfa, 0x93, 0xca, 0xd0, 0xf8, 0xdf,
-	0x5e, 0xb6, 0xed, 0xee, 0xc2, 0xff, 0x35, 0xd3, 0x0e, 0x98, 0xba, 0xbb, 0xaf, 0x82, 0x96, 0x17,
+	0x65, 0xf0, 0x7f, 0x45, 0xd0, 0xdc, 0x74, 0x79, 0x45, 0x5d, 0xf4, 0x64, 0x75, 0x6f, 0x28, 0x63,
-	0x67, 0xdb, 0x5e, 0x0c, 0x50, 0x64, 0x8f, 0xd1, 0xb0, 0x75, 0x72, 0xd6, 0x41, 0x5f, 0xcf, 0x3a,
+	0x3d, 0x4e, 0x99, 0xe7, 0xe0, 0x08, 0xc9, 0x69, 0x98, 0xaa, 0x1a, 0xd9, 0xc4, 0x58, 0xc5, 0x3e,
-	0xe8, 0xc7, 0x59, 0x07, 0x8d, 0x4d, 0xa9, 0xed, 0xd3, 0xdf, 0x01, 0x00, 0x00, 0xff, 0xff, 0xc0,
+	0x49, 0x45, 0xa4, 0x2a, 0xd4, 0x26, 0xc5, 0x71, 0xf4, 0x0f, 0x82, 0xfa, 0x37, 0xfa, 0x03, 0x87,
-	0x88, 0x4d, 0x15, 0x37, 0x07, 0x00, 0x00,
+	0xdf, 0x42, 0x73, 0xf3, 0x91, 0xc1, 0xfe, 0xf6, 0x54, 0xdf, 0xfe, 0x2a, 0x79, 0x1f, 0xdd, 0x8b,
+	0x31, 0xeb, 0xe9, 0x5b, 0xd8, 0x53, 0x1b, 0x11, 0x77, 0xef, 0x5f, 0xcf, 0x5e, 0x6f, 0xe7, 0xff,
+	0x86, 0xe9, 0x0d, 0x38, 0xa6, 0xbb, 0xef, 0x82, 0x56, 0x17, 0xa7, 0xd7, 0xdf, 0x0d, 0xd0, 0x64,
+	0x1f, 0xa3, 0x71, 0xfb, 0xe2, 0xaa, 0x8b, 0x7e, 0xbb, 0xea, 0xa2, 0x3f, 0xaf, 0xba, 0x68, 0xea,
+	0x28, 0x6d, 0x3f, 0xf9, 0x37, 0x00, 0x00, 0xff, 0xff, 0x97, 0xc3, 0x70, 0xc2, 0xef, 0x07, 0x00,
+	0x00,
 }

api/services/control/control.proto

@@ -32,6 +32,8 @@ message UsageRecord {
 message SolveRequest {
 	string Ref = 1;
 	repeated bytes Definition = 2; // TODO: remove repeated
+	string Exporter = 3;
+	map<string, string> ExporterAttrs = 4;
 }
 
 message SolveResponse {

cache/manager.go

@@ -92,6 +92,7 @@ func (cm *cacheManager) Get(ctx context.Context, id string) (ImmutableRef, error
 	defer cm.mu.Unlock()
 	return cm.get(ctx, id)
 }
+
 func (cm *cacheManager) get(ctx context.Context, id string) (ImmutableRef, error) {
 	rec, err := cm.load(ctx, id)
 	if err != nil {

cache/refs.go

@@ -16,6 +16,7 @@ type ImmutableRef interface {
 	ID() string
 	Release(context.Context) error
 	Size(ctx context.Context) (int64, error)
+	Parent() ImmutableRef
 	// Prepare() / ChainID() / Meta()
 }
 
@@ -85,6 +86,13 @@ func (cr *cacheRecord) Size(ctx context.Context) (int64, error) {
 	return s.(int64), err
 }
 
+func (cr *cacheRecord) Parent() ImmutableRef {
+	if cr.parent == nil {
+		return nil
+	}
+	return cr.parent.(*immutableRef).ref()
+}
+
 func (cr *cacheRecord) Mount(ctx context.Context) ([]mount.Mount, error) {
 	cr.mu.Lock()
 	defer cr.mu.Unlock()

client/client_test.go

@@ -95,6 +95,6 @@ func testBuildMultiMount(t *testing.T, address string) {
 	err = llb.WriteTo(dt, buf)
 	assert.Nil(t, err)
 
-	err = c.Solve(context.TODO(), buf, nil)
+	err = c.Solve(context.TODO(), buf, nil, "", nil)
 	assert.Nil(t, err)
 }

client/solve.go

@@ -13,7 +13,7 @@ import (
 	"golang.org/x/sync/errgroup"
 )
 
-func (c *Client) Solve(ctx context.Context, r io.Reader, statusChan chan *SolveStatus) error {
+func (c *Client) Solve(ctx context.Context, r io.Reader, statusChan chan *SolveStatus, exporter string, exporterAttrs map[string]string) error {
 	def, err := llb.ReadFrom(r)
 	if err != nil {
 		return errors.Wrap(err, "failed to parse input")
@@ -36,8 +36,10 @@ func (c *Client) Solve(ctx context.Context, r io.Reader, statusChan chan *SolveS
 			}()
 		}()
 		_, err = c.controlClient().Solve(ctx, &controlapi.SolveRequest{
-			Ref:        ref,
+			Ref:           ref,
-			Definition: def,
+			Definition:    def,
+			Exporter:      exporter,
+			ExporterAttrs: exporterAttrs,
 		})
 		if err != nil {
 			return errors.Wrap(err, "failed to solve")

cmd/buildctl/build.go

@@ -5,11 +5,13 @@ import (
 	"encoding/json"
 	"io/ioutil"
 	"os"
+	"strings"
 
 	"github.com/Sirupsen/logrus"
 	"github.com/moby/buildkit/client"
 	"github.com/moby/buildkit/util/appcontext"
 	"github.com/moby/buildkit/util/progress/progressui"
+	"github.com/pkg/errors"
 	"github.com/urfave/cli"
 	"golang.org/x/sync/errgroup"
 )
@@ -18,6 +20,16 @@ var buildCommand = cli.Command{
 	Name:   "build",
 	Usage:  "build",
 	Action: build,
+	Flags: []cli.Flag{
+		cli.StringFlag{
+			Name:  "exporter",
+			Usage: "Define exporter for build result",
+		},
+		cli.StringSliceFlag{
+			Name:  "exporter-opt",
+			Usage: "Define custom options for exporter",
+		},
+	},
 }
 
 func build(clicontext *cli.Context) error {
@@ -39,8 +51,13 @@ func build(clicontext *cli.Context) error {
 	displayCh := make(chan *client.SolveStatus)
 	eg, ctx := errgroup.WithContext(appcontext.Context())
 
+	exporterAttrs, err := attrMap(clicontext.StringSlice("exporter-opt"))
+	if err != nil {
+		return errors.Wrap(err, "invalid exporter-opt")
+	}
+
 	eg.Go(func() error {
-		return c.Solve(ctx, os.Stdin, ch)
+		return c.Solve(ctx, os.Stdin, ch, clicontext.String("exporter"), exporterAttrs)
 	})
 
 	eg.Go(func() error {
@@ -61,3 +78,15 @@ func build(clicontext *cli.Context) error {
 
 	return eg.Wait()
 }
+
+func attrMap(sl []string) (map[string]string, error) {
+	m := map[string]string{}
+	for _, v := range sl {
+		parts := strings.SplitN(v, "=", 2)
+		if len(parts) != 2 {
+			return nil, errors.Errorf("invalid value %s", v)
+		}
+		m[parts[0]] = parts[1]
+	}
+	return m, nil
+}

control/control.go

@@ -5,6 +5,7 @@ import (
 	controlapi "github.com/moby/buildkit/api/services/control"
 	"github.com/moby/buildkit/cache"
 	"github.com/moby/buildkit/client"
+	"github.com/moby/buildkit/exporter"
 	"github.com/moby/buildkit/solver"
 	"github.com/moby/buildkit/source"
 	"github.com/moby/buildkit/worker"
@@ -20,6 +21,7 @@ type Opt struct {
 	Worker           worker.Worker
 	SourceManager    *source.Manager
 	InstructionCache solver.InstructionCache
+	Exporters        map[string]exporter.Exporter
 }
 
 type Controller struct { // TODO: ControlService
@@ -68,7 +70,20 @@ func (c *Controller) Solve(ctx context.Context, req *controlapi.SolveRequest) (*
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to load")
 	}
-	if err := c.solver.Solve(ctx, req.Ref, v); err != nil {
+
+	var expi exporter.ExporterInstance
+	if req.Exporter != "" {
+		exp, ok := c.opt.Exporters[req.Exporter]
+		if !ok {
+			return nil, errors.Errorf("exporter %q could not be found", req.Exporter)
+		}
+		expi, err = exp.Resolve(ctx, req.ExporterAttrs)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if err := c.solver.Solve(ctx, req.Ref, v, expi); err != nil {
 		return nil, err
 	}
 	return &controlapi.SolveResponse{}, nil

control/control_containerd.go

@@ -44,10 +44,13 @@ func NewContainerd(root, address string) (*Controller, error) {
 }
 
 func newContainerdPullDeps(client *containerd.Client) *pullDeps {
+	diff := client.DiffService()
 	return &pullDeps{
 		Snapshotter:  client.SnapshotService(),
 		ContentStore: client.ContentStore(),
-		Applier:      client.DiffService(),
+		Applier:      diff,
+		Differ:       diff,
+		Images:       client.ImageService(),
 	}
 }
 

control/control_default.go

@@ -6,21 +6,28 @@ import (
 	"path/filepath"
 
 	"github.com/containerd/containerd/content"
+	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/rootfs"
 	ctdsnapshot "github.com/containerd/containerd/snapshot"
 	"github.com/moby/buildkit/cache"
 	"github.com/moby/buildkit/cache/instructioncache"
 	"github.com/moby/buildkit/cache/metadata"
+	"github.com/moby/buildkit/exporter"
+	imageexporter "github.com/moby/buildkit/exporter/containerimage"
 	"github.com/moby/buildkit/snapshot/blobmapping"
 	"github.com/moby/buildkit/source"
 	"github.com/moby/buildkit/source/containerimage"
 	"github.com/moby/buildkit/source/git"
 )
 
+const keyImageExporter = "image"
+
 type pullDeps struct {
 	Snapshotter  ctdsnapshot.Snapshotter
 	ContentStore content.Store
 	Applier      rootfs.Applier
+	Differ       rootfs.MountDiffer
+	Images       images.Store
 }
 
 func defaultControllerOpts(root string, pd pullDeps) (*Opt, error) {
@@ -78,10 +85,25 @@ func defaultControllerOpts(root string, pd pullDeps) (*Opt, error) {
 
 	sm.Register(gs)
 
+	exporters := map[string]exporter.Exporter{}
+
+	imageExporter, err := imageexporter.New(imageexporter.Opt{
+		Snapshotter:   snapshotter,
+		ContentStore:  pd.ContentStore,
+		Differ:        pd.Differ,
+		CacheAccessor: cm,
+		Images:        pd.Images,
+	})
+	if err != nil {
+		return nil, err
+	}
+	exporters[keyImageExporter] = imageExporter
+
 	return &Opt{
 		Snapshotter:      snapshotter,
 		CacheManager:     cm,
 		SourceManager:    sm,
 		InstructionCache: ic,
+		Exporters:        exporters,
 	}, nil
 }

control/control_standalone.go

@@ -12,6 +12,7 @@ import (
 	"github.com/containerd/containerd/archive"
 	"github.com/containerd/containerd/archive/compression"
 	"github.com/containerd/containerd/content"
+	"github.com/containerd/containerd/differ"
 	"github.com/containerd/containerd/mount"
 	"github.com/containerd/containerd/namespaces"
 	ctdsnapshot "github.com/containerd/containerd/snapshot"
@@ -61,12 +62,16 @@ func newStandalonePullDeps(root string) (*pullDeps, error) {
 		return nil, err
 	}
 
-	a := &localApplier{root: root, content: c}
+	differ, err := differ.NewBaseDiff(c)
+	if err != nil {
+		return nil, err
+	}
 
 	return &pullDeps{
 		Snapshotter:  &nsSnapshotter{s},
 		ContentStore: c,
-		Applier:      a,
+		Applier:      differ,
+		Differ:       differ,
 	}, nil
 }
 

exporter/containerimage/export.go

@@ -0,0 +1,228 @@
+package containerimage
+
+import (
+	"bytes"
+	gocontext "context"
+	"encoding/json"
+	"runtime"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/containerd/containerd/content"
+	"github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/mount"
+	"github.com/containerd/containerd/rootfs"
+	"github.com/moby/buildkit/cache"
+	"github.com/moby/buildkit/cache/metadata"
+	"github.com/moby/buildkit/exporter"
+	"github.com/moby/buildkit/snapshot"
+	"github.com/moby/buildkit/util/flightcontrol"
+	"github.com/moby/buildkit/util/system"
+	digest "github.com/opencontainers/go-digest"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/pkg/errors"
+	"golang.org/x/net/context"
+	"golang.org/x/sync/errgroup"
+)
+
+const (
+	keyImageName = "name"
+)
+
+type Opt struct {
+	Snapshotter   snapshot.Snapshotter
+	ContentStore  content.Store
+	Differ        rootfs.MountDiffer
+	CacheAccessor cache.Accessor
+	MetadataStore metadata.Store
+	Images        images.Store
+}
+
+type imageExporter struct {
+	blobmap blobmapper
+	opt     Opt
+	g       flightcontrol.Group
+}
+
+type diffPair struct {
+	diffID  digest.Digest
+	blobsum digest.Digest
+}
+
+type blobmapper interface {
+	GetBlob(ctx gocontext.Context, key string) (digest.Digest, error)
+	SetBlob(ctx gocontext.Context, key string, blob digest.Digest) error
+}
+
+func New(opt Opt) (exporter.Exporter, error) {
+	blobmap, ok := opt.Snapshotter.(blobmapper)
+	if !ok {
+		return nil, errors.Errorf("image exporter requires snapshotter with blobs mapping support")
+	}
+
+	im := &imageExporter{opt: opt, blobmap: blobmap}
+	return im, nil
+}
+
+func (e *imageExporter) Resolve(ctx context.Context, opt map[string]string) (exporter.ExporterInstance, error) {
+	i := &imageExporterInstance{imageExporter: e}
+	for k, v := range opt {
+		switch k {
+		case keyImageName:
+			i.targetName = v
+		default:
+			logrus.Warnf("unknown exporter option %s", k)
+		}
+	}
+	return i, nil
+}
+
+func (e *imageExporter) getBlobs(ctx context.Context, ref cache.ImmutableRef) ([]diffPair, error) {
+	eg, ctx := errgroup.WithContext(ctx)
+	var diffPairs []diffPair
+	var currentPair diffPair
+	parent := ref.Parent()
+	if parent != nil {
+		defer parent.Release(context.TODO())
+		eg.Go(func() error {
+			dp, err := e.getBlobs(ctx, parent)
+			if err != nil {
+				return err
+			}
+			diffPairs = dp
+			return nil
+		})
+	}
+	eg.Go(func() error {
+		dp, err := e.g.Do(ctx, ref.ID(), func(ctx context.Context) (interface{}, error) {
+			blob, err := e.blobmap.GetBlob(ctx, ref.ID())
+			if err != nil {
+				return nil, err
+			}
+			if blob != "" {
+				diffID, err := digest.Parse(ref.ID())
+				if err != nil {
+					diffID = blob
+				}
+				return diffPair{diffID: diffID, blobsum: blob}, nil
+			}
+			// reference needs to be committed
+			parent := ref.Parent()
+			var lower []mount.Mount
+			if parent != nil {
+				defer parent.Release(context.TODO())
+				lower, err = parent.Mount(ctx)
+				if err != nil {
+					return nil, err
+				}
+			}
+			upper, err := ref.Mount(ctx)
+			if err != nil {
+				return nil, err
+			}
+			descr, err := e.opt.Differ.DiffMounts(ctx, lower, upper, ocispec.MediaTypeImageLayer, ref.ID())
+			if err != nil {
+				return nil, err
+			}
+			if err := e.blobmap.SetBlob(ctx, ref.ID(), descr.Digest); err != nil {
+				return nil, err
+			}
+			return diffPair{diffID: descr.Digest, blobsum: descr.Digest}, nil
+		})
+		if err != nil {
+			return err
+		}
+		currentPair = dp.(diffPair)
+		return nil
+	})
+	err := eg.Wait()
+	if err != nil {
+		return nil, err
+	}
+	return append(diffPairs, currentPair), nil
+}
+
+type imageExporterInstance struct {
+	*imageExporter
+	targetName string
+}
+
+func (e *imageExporterInstance) Export(ctx context.Context, ref cache.ImmutableRef) error {
+	diffPairs, err := e.getBlobs(ctx, ref)
+	if err != nil {
+		return err
+	}
+
+	diffIDs := make([]digest.Digest, 0, len(diffPairs))
+	for _, dp := range diffPairs {
+		diffIDs = append(diffIDs, dp.diffID)
+	}
+
+	dt, err := json.Marshal(imageConfig(diffIDs))
+	if err != nil {
+		return errors.Wrap(err, "failed to marshal image config")
+	}
+
+	dgst := digest.FromBytes(dt)
+
+	if err := content.WriteBlob(ctx, e.opt.ContentStore, dgst.String(), bytes.NewReader(dt), int64(len(dt)), dgst); err != nil {
+		return errors.Wrap(err, "error writing config blob")
+	}
+
+	mfst := ocispec.Manifest{
+		Config: ocispec.Descriptor{
+			Digest:    dgst,
+			Size:      int64(len(dt)),
+			MediaType: ocispec.MediaTypeImageConfig,
+		},
+	}
+	mfst.SchemaVersion = 2
+
+	for _, dp := range diffPairs {
+		info, err := e.opt.ContentStore.Info(ctx, dp.blobsum)
+		if err != nil {
+			return errors.Wrapf(err, "could not get blob %s", dp.blobsum)
+		}
+		mfst.Layers = append(mfst.Layers, ocispec.Descriptor{
+			Digest:    dp.blobsum,
+			Size:      info.Size,
+			MediaType: ocispec.MediaTypeImageLayerGzip,
+		})
+	}
+
+	dt, err = json.Marshal(mfst)
+	if err != nil {
+		return errors.Wrap(err, "failed to marshal manifest")
+	}
+
+	dgst = digest.FromBytes(dt)
+
+	if err := content.WriteBlob(ctx, e.opt.ContentStore, dgst.String(), bytes.NewReader(dt), int64(len(dt)), dgst); err != nil {
+		return errors.Wrap(err, "error writing manifest blob")
+	}
+
+	logrus.Debugf("wrote manifest %s", dgst)
+
+	if e.opt.Images != nil && e.targetName != "" {
+		e.opt.Images.Update(ctx, e.targetName, ocispec.Descriptor{
+			Digest:    dgst,
+			Size:      int64(len(dt)),
+			MediaType: ocispec.MediaTypeImageManifest,
+		})
+		logrus.Debugf("updated tag for %s", e.targetName)
+	}
+
+	return err
+}
+
+// this is temporary: should move to dockerfile frontend
+func imageConfig(diffIDs []digest.Digest) ocispec.Image {
+	img := ocispec.Image{
+		Architecture: runtime.GOARCH,
+		OS:           runtime.GOOS,
+	}
+	img.RootFS.Type = "layers"
+	img.RootFS.DiffIDs = diffIDs
+	img.Config.WorkingDir = "/"
+	img.Config.Env = []string{"PATH=" + system.DefaultPathEnv}
+	return img
+}

exporter/exporter.go

@@ -0,0 +1,14 @@
+package exporter
+
+import (
+	"github.com/moby/buildkit/cache"
+	"golang.org/x/net/context"
+)
+
+type Exporter interface {
+	Resolve(context.Context, map[string]string) (ExporterInstance, error)
+}
+
+type ExporterInstance interface {
+	Export(context.Context, cache.ImmutableRef) error
+}

gometalinter.json

@@ -1,7 +1,7 @@
 {
   "Vendor": true,
   "Deadline": "8m",
-  "Exclude": ["solver/pb/ops.pb.go"],
+  "Exclude": ["solver/pb/ops.pb.go", "api/services/control/control.pb.go"],
   "DisableAll": true,
   "Enable": [
     "gofmt",

solver/exec.go

@@ -65,13 +65,8 @@ func (e *execOp) Run(ctx context.Context, inputs []Reference) ([]Reference, erro
 				return nil, errors.Errorf("missing input %d", m.Input)
 			}
 			inp := inputs[int(m.Input)]
-			if sys, ok := inp.(interface {
-				Sys() Reference
-			}); ok {
-				inp = sys.Sys()
-			}
 			var ok bool
-			ref, ok = inp.(cache.ImmutableRef)
+			ref, ok = toImmutableRef(inp)
 			if !ok {
 				return nil, errors.Errorf("invalid reference for exec %T", inputs[int(m.Input)])
 			}

solver/solver.go

@@ -4,6 +4,7 @@ import (
 	"github.com/Sirupsen/logrus"
 	"github.com/moby/buildkit/cache"
 	"github.com/moby/buildkit/client"
+	"github.com/moby/buildkit/exporter"
 	"github.com/moby/buildkit/solver/pb"
 	"github.com/moby/buildkit/source"
 	"github.com/moby/buildkit/util/progress"
@@ -63,7 +64,7 @@ func New(resolve ResolveOpFunc, cache InstructionCache) *Solver {
 	return &Solver{resolve: resolve, jobs: newJobList(), cache: cache}
 }
 
-func (s *Solver) Solve(ctx context.Context, id string, v Vertex) error {
+func (s *Solver) Solve(ctx context.Context, id string, v Vertex, exp exporter.ExporterInstance) error {
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
 
@@ -87,10 +88,22 @@ func (s *Solver) Solve(ctx context.Context, id string, v Vertex) error {
 		return err
 	}
 
-	for _, r := range refs {
+	defer func() {
-		r.Release(context.TODO())
+		for _, r := range refs {
+			r.Release(context.TODO())
+		}
+	}()
+
+	if exp != nil {
+		immutable, ok := toImmutableRef(refs[0])
+		if !ok {
+			return errors.Errorf("invalid reference for exporting: %T", refs[0])
+		}
+		if err := exp.Export(ctx, immutable); err != nil {
+			return err
+		}
 	}
-	// TODO: export final vertex state
+
 	return err
 }
 
@@ -264,3 +277,26 @@ func toAny(in []Reference) []interface{} {
 	}
 	return out
 }
+
+func toImmutableRef(ref Reference) (cache.ImmutableRef, bool) {
+	sysRef := ref
+	if sys, ok := ref.(interface {
+		Sys() Reference
+	}); ok {
+		sysRef = sys.Sys()
+	}
+	immutable, ok := sysRef.(cache.ImmutableRef)
+	if !ok {
+		return nil, false
+	}
+	return &immutableRef{immutable, ref.Release}, true
+}
+
+type immutableRef struct {
+	cache.ImmutableRef
+	release func(context.Context) error
+}
+
+func (ir *immutableRef) Release(ctx context.Context) error {
+	return ir.release(ctx)
+}