Merge pull request #213 from tonistiigi/dockerfile-dedupe

frontend: make dockerfile.v0 and external frontend use same code

cache/fsutil.go

@@ -0,0 +1,45 @@
+package cache
+
+import (
+	"io/ioutil"
+	"path/filepath"
+
+	"github.com/docker/docker/pkg/symlink"
+	"github.com/moby/buildkit/snapshot"
+	"golang.org/x/net/context"
+)
+
+func ReadFile(ctx context.Context, ref ImmutableRef, p string) ([]byte, error) {
+	mount, err := ref.Mount(ctx, false)
+	if err != nil {
+		return nil, err
+	}
+
+	lm := snapshot.LocalMounter(mount)
+
+	root, err := lm.Mount()
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() {
+		if lm != nil {
+			lm.Unmount()
+		}
+	}()
+
+	fp, err := symlink.FollowSymlinkInScope(filepath.Join(root, p), root)
+	if err != nil {
+		return nil, err
+	}
+
+	dt, err := ioutil.ReadFile(fp)
+	if err != nil {
+		return nil, err
+	}
+	if err := lm.Unmount(); err != nil {
+		return nil, err
+	}
+	lm = nil
+	return dt, err
+}

frontend/dockerfile/builder/build.go

@@ -0,0 +1,110 @@
+package builder
+
+import (
+	"context"
+	"encoding/json"
+	"path"
+	"strings"
+
+	"github.com/moby/buildkit/client/llb"
+	"github.com/moby/buildkit/frontend/dockerfile/dockerfile2llb"
+	"github.com/moby/buildkit/frontend/gateway/client"
+	"github.com/pkg/errors"
+)
+
+const (
+	LocalNameContext      = "context"
+	LocalNameDockerfile   = "dockerfile"
+	keyTarget             = "target"
+	keyFilename           = "filename"
+	exporterImageConfig   = "containerimage.config"
+	defaultDockerfileName = "Dockerfile"
+	buildArgPrefix        = "build-arg:"
+	gitPrefix             = "git://"
+)
+
+func Build(ctx context.Context, c client.Client) error {
+	opts := c.Opts()
+
+	filename := opts[keyFilename]
+	if filename == "" {
+		filename = defaultDockerfileName
+	}
+	if path.Base(filename) != filename {
+		return errors.Errorf("invalid filename: %s", filename)
+	}
+
+	src := llb.Local(LocalNameDockerfile,
+		llb.IncludePatterns([]string{filename}),
+		llb.SessionID(c.SessionID()),
+	)
+	var buildContext *llb.State
+	if strings.HasPrefix(opts[LocalNameContext], gitPrefix) {
+		src = parseGitSource(opts[LocalNameContext])
+		buildContext = &src
+	}
+	def, err := src.Marshal()
+	if err != nil {
+		return err
+	}
+
+	ref, err := c.Solve(ctx, def.ToPB(), "", nil, false)
+	if err != nil {
+		return err
+	}
+
+	dtDockerfile, err := ref.ReadFile(ctx, filename)
+	if err != nil {
+		return err
+	}
+
+	st, img, err := dockerfile2llb.Dockerfile2LLB(ctx, dtDockerfile, dockerfile2llb.ConvertOpt{
+		Target:       opts[keyTarget],
+		MetaResolver: c,
+		BuildArgs:    filterBuildArgs(opts),
+		SessionID:    c.SessionID(),
+		BuildContext: buildContext,
+	})
+
+	if err != nil {
+		return err
+	}
+
+	def, err = st.Marshal()
+	if err != nil {
+		return err
+	}
+
+	config, err := json.Marshal(img)
+	if err != nil {
+		return err
+	}
+
+	_, err = c.Solve(ctx, def.ToPB(), "", map[string][]byte{
+		exporterImageConfig: config,
+	}, true)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func filterBuildArgs(opt map[string]string) map[string]string {
+	m := map[string]string{}
+	for k, v := range opt {
+		if strings.HasPrefix(k, buildArgPrefix) {
+			m[strings.TrimPrefix(k, buildArgPrefix)] = v
+		}
+	}
+	return m
+}
+
+func parseGitSource(ref string) llb.State {
+	ref = strings.TrimPrefix(ref, gitPrefix)
+	parts := strings.SplitN(ref, "#", 2)
+	branch := ""
+	if len(parts) > 1 {
+		branch = parts[1]
+	}
+	return llb.Git(parts[0], branch)
+}

frontend/dockerfile/cmd/dockerfile-frontend/main.go

@@ -1,29 +1,13 @@
 package main
 
 import (
-	"encoding/json"
+	"github.com/moby/buildkit/frontend/dockerfile/builder"
-	"path"
+	"github.com/moby/buildkit/frontend/gateway/grpcclient"
-	"strings"
-
-	"github.com/moby/buildkit/client/llb"
-	"github.com/moby/buildkit/frontend/dockerfile/dockerfile2llb"
-	"github.com/moby/buildkit/frontend/gateway/client"
 	"github.com/moby/buildkit/util/appcontext"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
-const (
-	keyTarget             = "target"
-	keyFilename           = "filename"
-	exporterImageConfig   = "containerimage.config"
-	defaultDockerfileName = "Dockerfile"
-	localNameDockerfile   = "dockerfile"
-	buildArgPrefix        = "build-arg:"
-	localNameContext      = "context"
-	gitPrefix             = "git://"
-)
-
 func main() {
 	if err := run(); err != nil {
 		logrus.Errorf("fatal error: %+v", err)
@@ -32,94 +16,10 @@ func main() {
 }
 
 func run() error {
-	c, err := client.Current()
+	c, err := grpcclient.Current()
 	if err != nil {
 		return errors.Wrap(err, "failed to create client")
 	}
 
-	ctx := appcontext.Context()
+	return builder.Build(appcontext.Context(), c)
-
-	opts := c.Opts()
-
-	filename := opts[keyFilename]
-	if filename == "" {
-		filename = defaultDockerfileName
-	}
-	if path.Base(filename) != filename {
-		return errors.Errorf("invalid filename: %s", filename)
-	}
-
-	src := llb.Local(localNameDockerfile,
-		llb.IncludePatterns([]string{filename}),
-		llb.SessionID(c.SessionID()),
-	)
-	var buildContext *llb.State
-	if strings.HasPrefix(opts[localNameContext], gitPrefix) {
-		src = parseGitSource(opts[localNameContext])
-		buildContext = &src
-	}
-	def, err := src.Marshal()
-	if err != nil {
-		return err
-	}
-
-	ref, err := c.Solve(ctx, def.ToPB(), "", nil, false)
-	if err != nil {
-		return err
-	}
-
-	dtDockerfile, err := ref.ReadFile(ctx, filename)
-	if err != nil {
-		return err
-	}
-
-	st, img, err := dockerfile2llb.Dockerfile2LLB(ctx, dtDockerfile, dockerfile2llb.ConvertOpt{
-		Target:       opts[keyTarget],
-		MetaResolver: c,
-		BuildArgs:    filterBuildArgs(opts),
-		SessionID:    c.SessionID(),
-		BuildContext: buildContext,
-	})
-
-	if err != nil {
-		return err
-	}
-
-	def, err = st.Marshal()
-	if err != nil {
-		return err
-	}
-
-	config, err := json.Marshal(img)
-	if err != nil {
-		return err
-	}
-
-	_, err = c.Solve(ctx, def.ToPB(), "", map[string][]byte{
-		exporterImageConfig: config,
-	}, true)
-	if err != nil {
-		return err
-	}
-	return nil
-}
-
-func filterBuildArgs(opt map[string]string) map[string]string {
-	m := map[string]string{}
-	for k, v := range opt {
-		if strings.HasPrefix(k, buildArgPrefix) {
-			m[strings.TrimPrefix(k, buildArgPrefix)] = v
-		}
-	}
-	return m
-}
-
-func parseGitSource(ref string) llb.State {
-	ref = strings.TrimPrefix(ref, gitPrefix)
-	parts := strings.SplitN(ref, "#", 2)
-	branch := ""
-	if len(parts) > 1 {
-		branch = parts[1]
-	}
-	return llb.Git(parts[0], branch)
 }

frontend/dockerfile/dockerfile.go

@@ -1,33 +1,14 @@
 package dockerfile
 
 import (
-	"encoding/json"
-	"io/ioutil"
-	"path"
-	"path/filepath"
-	"strings"
-
 	"github.com/moby/buildkit/cache"
-	"github.com/moby/buildkit/client/llb"
 	"github.com/moby/buildkit/frontend"
-	"github.com/moby/buildkit/frontend/dockerfile/dockerfile2llb"
+	"github.com/moby/buildkit/frontend/dockerfile/builder"
-	"github.com/moby/buildkit/session"
+	"github.com/moby/buildkit/util/appcontext"
-	"github.com/moby/buildkit/snapshot"
 	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 )
 
-const (
-	keyTarget             = "target"
-	keyFilename           = "filename"
-	exporterImageConfig   = "containerimage.config"
-	defaultDockerfileName = "Dockerfile"
-	localNameDockerfile   = "dockerfile"
-	buildArgPrefix        = "build-arg:"
-	localNameContext      = "context"
-	gitPrefix             = "git://"
-)
-
 func NewDockerfileFrontend() frontend.Frontend {
 	return &dfFrontend{}
 }
@@ -35,127 +16,27 @@ func NewDockerfileFrontend() frontend.Frontend {
 type dfFrontend struct{}
 
 func (f *dfFrontend) Solve(ctx context.Context, llbBridge frontend.FrontendLLBBridge, opts map[string]string) (retRef cache.ImmutableRef, exporterAttr map[string][]byte, retErr error) {
-	filename := opts[keyFilename]
-	if filename == "" {
-		filename = defaultDockerfileName
-	}
-	if path.Base(filename) != filename {
-		return nil, nil, errors.Errorf("invalid filename %s", filename)
-	}
 
-	sid := session.FromContext(ctx)
+	c, err := llbBridgeToGatewayClient(ctx, llbBridge, opts)
-
-	src := llb.Local(localNameDockerfile,
-		llb.IncludePatterns([]string{filename}),
-		llb.SessionID(sid),
-	)
-
-	var buildContext *llb.State
-	if strings.HasPrefix(opts[localNameContext], gitPrefix) {
-		src = parseGitSource(opts[localNameContext])
-		buildContext = &src
-	}
-
-	def, err := src.Marshal()
-	if err != nil {
-		return nil, nil, err
-	}
-
-	ref, _, err := llbBridge.Solve(ctx, frontend.SolveRequest{
-		Definition: def.ToPB(),
-	})
 	if err != nil {
 		return nil, nil, err
 	}
 
 	defer func() {
-		if ref != nil {
+		for _, r := range c.refs {
-			ref.Release(context.TODO())
+			if r != nil && (c.final != r || retErr != nil) {
+				r.Release(context.TODO())
+			}
 		}
 	}()
 
-	mount, err := ref.Mount(ctx, false)
+	if err := builder.Build(appcontext.Context(), c); err != nil {
-	if err != nil {
 		return nil, nil, err
 	}
 
-	lm := snapshot.LocalMounter(mount)
+	if c.final == nil {
-
+		return nil, nil, errors.Errorf("invalid empty return") // shouldn't happen
-	root, err := lm.Mount()
-	if err != nil {
-		return nil, nil, err
 	}
 
-	defer func() {
+	return c.final.ImmutableRef, c.exporterAttr, nil
-		if lm != nil {
-			lm.Unmount()
-		}
-	}()
-
-	dtDockerfile, err := ioutil.ReadFile(filepath.Join(root, filename))
-	if err != nil {
-		return nil, nil, err
-	}
-
-	if err := lm.Unmount(); err != nil {
-		return nil, nil, err
-	}
-	lm = nil
-
-	if err := ref.Release(context.TODO()); err != nil {
-		return nil, nil, err
-	}
-	ref = nil
-
-	st, img, err := dockerfile2llb.Dockerfile2LLB(ctx, dtDockerfile, dockerfile2llb.ConvertOpt{
-		Target:       opts[keyTarget],
-		MetaResolver: llbBridge,
-		BuildArgs:    filterBuildArgs(opts),
-		SessionID:    sid,
-		BuildContext: buildContext,
-	})
-
-	if err != nil {
-		return nil, nil, err
-	}
-
-	def, err = st.Marshal()
-	if err != nil {
-		return nil, nil, err
-	}
-	retRef, _, err = llbBridge.Solve(ctx, frontend.SolveRequest{
-		Definition: def.ToPB(),
-	})
-	if err != nil {
-		return nil, nil, err
-	}
-
-	config, err := json.Marshal(img)
-	if err != nil {
-		return nil, nil, err
-	}
-
-	return retRef, map[string][]byte{
-		exporterImageConfig: config,
-	}, nil
-}
-
-func filterBuildArgs(opt map[string]string) map[string]string {
-	m := map[string]string{}
-	for k, v := range opt {
-		if strings.HasPrefix(k, buildArgPrefix) {
-			m[strings.TrimPrefix(k, buildArgPrefix)] = v
-		}
-	}
-	return m
-}
-
-func parseGitSource(ref string) llb.State {
-	ref = strings.TrimPrefix(ref, gitPrefix)
-	parts := strings.SplitN(ref, "#", 2)
-	branch := ""
-	if len(parts) > 1 {
-		branch = parts[1]
-	}
-	return llb.Git(parts[0], branch)
 }

frontend/dockerfile/dockerfile_test.go

@@ -22,6 +22,7 @@ import (
 	"github.com/containerd/containerd/namespaces"
 	"github.com/containerd/containerd/platforms"
 	"github.com/moby/buildkit/client"
+	"github.com/moby/buildkit/frontend/dockerfile/builder"
 	"github.com/moby/buildkit/identity"
 	"github.com/moby/buildkit/util/testutil/httpserver"
 	"github.com/moby/buildkit/util/testutil/integration"
@@ -454,8 +455,8 @@ EXPOSE 5000
 			"name": target,
 		},
 		LocalDirs: map[string]string{
-			localNameDockerfile: dir,
+			builder.LocalNameDockerfile: dir,
-			localNameContext:    dir,
+			builder.LocalNameContext:    dir,
 		},
 	}, nil)
 	require.NoError(t, err)
@@ -611,8 +612,8 @@ USER nobody
 			"output": destDir,
 		},
 		LocalDirs: map[string]string{
-			localNameDockerfile: dir,
+			builder.LocalNameDockerfile: dir,
-			localNameContext:    dir,
+			builder.LocalNameContext:    dir,
 		},
 	}, nil)
 	require.NoError(t, err)
@@ -634,8 +635,8 @@ USER nobody
 			"name": target,
 		},
 		LocalDirs: map[string]string{
-			localNameDockerfile: dir,
+			builder.LocalNameDockerfile: dir,
-			localNameContext:    dir,
+			builder.LocalNameContext:    dir,
 		},
 	}, nil)
 	require.NoError(t, err)

frontend/dockerfile/forward.go

@@ -0,0 +1,66 @@
+package dockerfile
+
+import (
+	"os"
+
+	"github.com/moby/buildkit/cache"
+	"github.com/moby/buildkit/frontend"
+	"github.com/moby/buildkit/frontend/gateway/client"
+	"github.com/moby/buildkit/session"
+	"github.com/moby/buildkit/solver/pb"
+	"github.com/pkg/errors"
+	"golang.org/x/net/context"
+)
+
+func llbBridgeToGatewayClient(ctx context.Context, llbBridge frontend.FrontendLLBBridge, opts map[string]string) (*bridgeClient, error) {
+	return &bridgeClient{opts: opts, FrontendLLBBridge: llbBridge, sid: session.FromContext(ctx)}, nil
+}
+
+type bridgeClient struct {
+	frontend.FrontendLLBBridge
+	opts         map[string]string
+	final        *ref
+	sid          string
+	exporterAttr map[string][]byte
+	refs         []*ref
+}
+
+func (c *bridgeClient) Solve(ctx context.Context, def *pb.Definition, f string, exporterAttr map[string][]byte, final bool) (client.Reference, error) {
+	r, exporterAttrRes, err := c.FrontendLLBBridge.Solve(ctx, frontend.SolveRequest{
+		Definition: def,
+		Frontend:   f,
+	})
+	if err != nil {
+		return nil, err
+	}
+	rr := &ref{r}
+	c.refs = append(c.refs, rr)
+	if final {
+		c.final = rr
+		if exporterAttr == nil {
+			exporterAttr = make(map[string][]byte)
+		}
+		for k, v := range exporterAttrRes {
+			exporterAttr[k] = v
+		}
+		c.exporterAttr = exporterAttr
+	}
+	return rr, nil
+}
+func (c *bridgeClient) Opts() map[string]string {
+	return c.opts
+}
+func (c *bridgeClient) SessionID() string {
+	return c.sid
+}
+
+type ref struct {
+	cache.ImmutableRef
+}
+
+func (r *ref) ReadFile(ctx context.Context, fp string) ([]byte, error) {
+	if r.ImmutableRef == nil {
+		return nil, errors.Wrapf(os.ErrNotExist, "%s no found", fp)
+	}
+	return cache.ReadFile(ctx, r.ImmutableRef, fp)
+}

frontend/gateway/client/client.go

@@ -1,163 +1,19 @@
 package client
 
 import (
-	"encoding/json"
+	"github.com/moby/buildkit/solver/pb"
-	"io"
-	"net"
-	"os"
-	"strings"
-	"time"
-
-	pb "github.com/moby/buildkit/frontend/gateway/pb"
-	opspb "github.com/moby/buildkit/solver/pb"
 	digest "github.com/opencontainers/go-digest"
-	"github.com/pkg/errors"
 	"golang.org/x/net/context"
-	"google.golang.org/grpc"
 )
 
-const frontendPrefix = "BUILDKIT_FRONTEND_OPT_"
+// TODO: make this take same options as LLBBridge. Add Return()
-
+type Client interface {
-func Current() (*Client, error) {
+	Solve(ctx context.Context, def *pb.Definition, frontend string, exporterAttr map[string][]byte, final bool) (Reference, error)
-	ctx, conn, err := grpcClientConn(context.Background())
+	ResolveImageConfig(ctx context.Context, ref string) (digest.Digest, []byte, error)
-	if err != nil {
+	Opts() map[string]string
-		return nil, err
+	SessionID() string
-	}
-
-	c := pb.NewLLBBridgeClient(conn)
-
-	_, err = c.Ping(ctx, &pb.PingRequest{})
-	if err != nil {
-		return nil, err
-	}
-
-	return &Client{client: c, opts: opts(), sessionID: sessionID()}, nil
 }
 
-type Client struct {
+type Reference interface {
-	client    pb.LLBBridgeClient
+	ReadFile(ctx context.Context, fp string) ([]byte, error)
-	opts      map[string]string
-	sessionID string
-}
-
-func (c *Client) Solve(ctx context.Context, def *opspb.Definition, frontend string, exporterAttr map[string][]byte, final bool) (*Reference, error) {
-	dt, err := json.Marshal(exporterAttr)
-	if err != nil {
-		return nil, err
-	}
-	req := &pb.SolveRequest{Definition: def, Frontend: frontend, Final: final, ExporterAttr: dt}
-	resp, err := c.client.Solve(ctx, req)
-	if err != nil {
-		return nil, err
-	}
-	return &Reference{id: resp.Ref, c: c}, nil
-}
-
-func (c *Client) ResolveImageConfig(ctx context.Context, ref string) (digest.Digest, []byte, error) {
-	resp, err := c.client.ResolveImageConfig(ctx, &pb.ResolveImageConfigRequest{Ref: ref})
-	if err != nil {
-		return "", nil, err
-	}
-	return resp.Digest, resp.Config, nil
-}
-
-func (c *Client) Opts() map[string]string {
-	return c.opts
-}
-
-func (c *Client) SessionID() string {
-	return c.sessionID
-}
-
-type Reference struct {
-	id string
-	c  *Client
-}
-
-func (r *Reference) ReadFile(ctx context.Context, fp string) ([]byte, error) {
-	resp, err := r.c.client.ReadFile(ctx, &pb.ReadFileRequest{FilePath: fp, Ref: r.id})
-	if err != nil {
-		return nil, err
-	}
-	return resp.Data, nil
-}
-
-func grpcClientConn(ctx context.Context) (context.Context, *grpc.ClientConn, error) {
-	dialOpt := grpc.WithDialer(func(addr string, d time.Duration) (net.Conn, error) {
-		return stdioConn(), nil
-	})
-
-	cc, err := grpc.DialContext(ctx, "", dialOpt, grpc.WithInsecure())
-	if err != nil {
-		return nil, nil, errors.Wrap(err, "failed to create grpc client")
-	}
-
-	ctx, cancel := context.WithCancel(ctx)
-	_ = cancel
-	// go monitorHealth(ctx, cc, cancel)
-
-	return ctx, cc, nil
-}
-
-func stdioConn() net.Conn {
-	return &conn{os.Stdin, os.Stdout, os.Stdout}
-}
-
-type conn struct {
-	io.Reader
-	io.Writer
-	io.Closer
-}
-
-func (s *conn) LocalAddr() net.Addr {
-	return dummyAddr{}
-}
-func (s *conn) RemoteAddr() net.Addr {
-	return dummyAddr{}
-}
-func (s *conn) SetDeadline(t time.Time) error {
-	return nil
-}
-func (s *conn) SetReadDeadline(t time.Time) error {
-	return nil
-}
-func (s *conn) SetWriteDeadline(t time.Time) error {
-	return nil
-}
-
-type dummyAddr struct {
-}
-
-func (d dummyAddr) Network() string {
-	return "pipe"
-}
-
-func (d dummyAddr) String() string {
-	return "localhost"
-}
-
-func opts() map[string]string {
-	opts := map[string]string{}
-	for _, env := range os.Environ() {
-		parts := strings.SplitN(env, "=", 2)
-		k := parts[0]
-		v := ""
-		if len(parts) == 2 {
-			v = parts[1]
-		}
-		if !strings.HasPrefix(k, frontendPrefix) {
-			continue
-		}
-		parts = strings.SplitN(v, "=", 2)
-		v = ""
-		if len(parts) == 2 {
-			v = parts[1]
-		}
-		opts[parts[0]] = v
-	}
-	return opts
-}
-
-func sessionID() string {
-	return os.Getenv("BUILDKIT_SESSION_ID")
 }

frontend/gateway/gateway.go

@@ -4,10 +4,8 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net"
 	"os"
-	"path/filepath"
 	"strings"
 	"time"
 
@@ -19,7 +17,6 @@ import (
 	pb "github.com/moby/buildkit/frontend/gateway/pb"
 	"github.com/moby/buildkit/identity"
 	"github.com/moby/buildkit/session"
-	"github.com/moby/buildkit/snapshot"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -75,6 +72,7 @@ func (gf *gatewayFrontend) Solve(ctx context.Context, llbBridge frontend.Fronten
 		if err != nil {
 			return nil, nil, err
 		}
+		defer ref.Release(context.TODO())
 		rootFS = ref
 		config, ok := exp[exporterImageConfig]
 		if ok {
@@ -115,6 +113,7 @@ func (gf *gatewayFrontend) Solve(ctx context.Context, llbBridge frontend.Fronten
 		if err != nil {
 			return nil, nil, err
 		}
+		defer ref.Release(context.TODO())
 		rootFS = ref
 	}
 
@@ -144,6 +143,14 @@ func (gf *gatewayFrontend) Solve(ctx context.Context, llbBridge frontend.Fronten
 
 	env = append(env, "BUILDKIT_SESSION_ID="+sid)
 
+	defer func() {
+		for _, r := range lbf.refs {
+			if r != nil && (lbf.lastRef != r || retErr != nil) {
+				r.Release(context.TODO())
+			}
+		}
+	}()
+
 	err = llbBridge.Exec(ctx, executor.Meta{
 		Env:  env,
 		Args: args,
@@ -271,6 +278,9 @@ func (lbf *llbBrideForwarder) Solve(ctx context.Context, req *pb.SolveRequest) (
 		lbf.lastRef = ref
 		lbf.exporterAttr = exp
 	}
+	if ref == nil {
+		id = ""
+	}
 	return &pb.SolveResponse{Ref: id}, nil
 }
 func (lbf *llbBrideForwarder) ReadFile(ctx context.Context, req *pb.ReadFileRequest) (*pb.ReadFileResponse, error) {
@@ -278,35 +288,14 @@ func (lbf *llbBrideForwarder) ReadFile(ctx context.Context, req *pb.ReadFileRequ
 	if !ok {
 		return nil, errors.Errorf("no such ref: %v", req.Ref)
 	}
-
+	if ref == nil {
-	mount, err := ref.Mount(ctx, false)
+		return nil, errors.Wrapf(os.ErrNotExist, "%s no found", req.FilePath)
+	}
+	dt, err := cache.ReadFile(ctx, ref, req.FilePath)
 	if err != nil {
 		return nil, err
 	}
 
-	lm := snapshot.LocalMounter(mount)
-
-	root, err := lm.Mount()
-	if err != nil {
-		return nil, err
-	}
-
-	defer func() {
-		if lm != nil {
-			lm.Unmount()
-		}
-	}()
-
-	dt, err := ioutil.ReadFile(filepath.Join(root, req.FilePath))
-	if err != nil {
-		return nil, err
-	}
-
-	if err := lm.Unmount(); err != nil {
-		return nil, err
-	}
-	lm = nil
-
 	return &pb.ReadFileResponse{Data: dt}, nil
 }
 

frontend/gateway/grpcclient/client.go

@@ -0,0 +1,167 @@
+package grpcclient
+
+import (
+	"encoding/json"
+	"io"
+	"net"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/moby/buildkit/frontend/gateway/client"
+	pb "github.com/moby/buildkit/frontend/gateway/pb"
+	opspb "github.com/moby/buildkit/solver/pb"
+	digest "github.com/opencontainers/go-digest"
+	"github.com/pkg/errors"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+)
+
+const frontendPrefix = "BUILDKIT_FRONTEND_OPT_"
+
+func Current() (client.Client, error) {
+	ctx, conn, err := grpcClientConn(context.Background())
+	if err != nil {
+		return nil, err
+	}
+
+	c := pb.NewLLBBridgeClient(conn)
+
+	_, err = c.Ping(ctx, &pb.PingRequest{})
+	if err != nil {
+		return nil, err
+	}
+
+	return &grpcClient{client: c, opts: opts(), sessionID: sessionID()}, nil
+}
+
+type grpcClient struct {
+	client    pb.LLBBridgeClient
+	opts      map[string]string
+	sessionID string
+}
+
+func (c *grpcClient) Solve(ctx context.Context, def *opspb.Definition, frontend string, exporterAttr map[string][]byte, final bool) (client.Reference, error) {
+	dt, err := json.Marshal(exporterAttr)
+	if err != nil {
+		return nil, err
+	}
+	req := &pb.SolveRequest{Definition: def, Frontend: frontend, Final: final, ExporterAttr: dt}
+	resp, err := c.client.Solve(ctx, req)
+	if err != nil {
+		return nil, err
+	}
+	if resp.Ref == "" {
+		return nil, nil
+	}
+	return &reference{id: resp.Ref, c: c}, nil
+}
+
+func (c *grpcClient) ResolveImageConfig(ctx context.Context, ref string) (digest.Digest, []byte, error) {
+	resp, err := c.client.ResolveImageConfig(ctx, &pb.ResolveImageConfigRequest{Ref: ref})
+	if err != nil {
+		return "", nil, err
+	}
+	return resp.Digest, resp.Config, nil
+}
+
+func (c *grpcClient) Opts() map[string]string {
+	return c.opts
+}
+
+func (c *grpcClient) SessionID() string {
+	return c.sessionID
+}
+
+type reference struct {
+	id string
+	c  *grpcClient
+}
+
+func (r *reference) ReadFile(ctx context.Context, fp string) ([]byte, error) {
+	resp, err := r.c.client.ReadFile(ctx, &pb.ReadFileRequest{FilePath: fp, Ref: r.id})
+	if err != nil {
+		return nil, err
+	}
+	return resp.Data, nil
+}
+
+func grpcClientConn(ctx context.Context) (context.Context, *grpc.ClientConn, error) {
+	dialOpt := grpc.WithDialer(func(addr string, d time.Duration) (net.Conn, error) {
+		return stdioConn(), nil
+	})
+
+	cc, err := grpc.DialContext(ctx, "", dialOpt, grpc.WithInsecure())
+	if err != nil {
+		return nil, nil, errors.Wrap(err, "failed to create grpc client")
+	}
+
+	ctx, cancel := context.WithCancel(ctx)
+	_ = cancel
+	// go monitorHealth(ctx, cc, cancel)
+
+	return ctx, cc, nil
+}
+
+func stdioConn() net.Conn {
+	return &conn{os.Stdin, os.Stdout, os.Stdout}
+}
+
+type conn struct {
+	io.Reader
+	io.Writer
+	io.Closer
+}
+
+func (s *conn) LocalAddr() net.Addr {
+	return dummyAddr{}
+}
+func (s *conn) RemoteAddr() net.Addr {
+	return dummyAddr{}
+}
+func (s *conn) SetDeadline(t time.Time) error {
+	return nil
+}
+func (s *conn) SetReadDeadline(t time.Time) error {
+	return nil
+}
+func (s *conn) SetWriteDeadline(t time.Time) error {
+	return nil
+}
+
+type dummyAddr struct {
+}
+
+func (d dummyAddr) Network() string {
+	return "pipe"
+}
+
+func (d dummyAddr) String() string {
+	return "localhost"
+}
+
+func opts() map[string]string {
+	opts := map[string]string{}
+	for _, env := range os.Environ() {
+		parts := strings.SplitN(env, "=", 2)
+		k := parts[0]
+		v := ""
+		if len(parts) == 2 {
+			v = parts[1]
+		}
+		if !strings.HasPrefix(k, frontendPrefix) {
+			continue
+		}
+		parts = strings.SplitN(v, "=", 2)
+		v = ""
+		if len(parts) == 2 {
+			v = parts[1]
+		}
+		opts[parts[0]] = v
+	}
+	return opts
+}
+
+func sessionID() string {
+	return os.Getenv("BUILDKIT_SESSION_ID")
+}

hack/test

@@ -8,3 +8,4 @@ docker build -t buildkit:test --target integration-tests -f ./hack/dockerfiles/t
 docker run --rm -v /tmp --privileged buildkit:test go test -tags standalone ${TESTFLAGS:--v} ${TESTPKGS:-./...}
 
 docker run --rm buildkit:test go build ./frontend/gateway/client
+docker run --rm buildkit:test go build ./frontend/dockerfile/cmd/dockerfile-frontend