moby · AkihiroSuda · Jun 27, 2018 · Jun 24, 2018 · Jun 25, 2018 · Jun 26, 2018
diff --git a/client/llb/imagemetaresolver/resolver.go b/client/llb/imagemetaresolver/resolver.go
@@ -12,6 +12,7 @@ import (
 	"github.com/moby/buildkit/util/contentutil"
 	"github.com/moby/buildkit/util/imageutil"
 	digest "github.com/opencontainers/go-digest"
+	specs "github.com/opencontainers/image-spec/specs-go/v1"
 )
 
 var defaultImageMetaResolver llb.ImageMetaResolver
@@ -22,12 +23,12 @@ var WithDefault = llb.ImageOptionFunc(func(ii *llb.ImageInfo) {
 })
 
 type imageMetaResolverOpts struct {
-	platform string
+	platform *specs.Platform
 }
 
 type ImageMetaResolverOpt func(o *imageMetaResolverOpts)
 
-func WithPlatform(p string) ImageMetaResolverOpt {
+func WithDefaultPlatform(p *specs.Platform) ImageMetaResolverOpt {
 	return func(o *imageMetaResolverOpts) {
 		o.platform = p
 	}
@@ -59,7 +60,7 @@ func Default() llb.ImageMetaResolver {
 type imageMetaResolver struct {
 	resolver remotes.Resolver
 	buffer   contentutil.Buffer
-	platform string
+	platform *specs.Platform
 	locker   *locker.Locker
 	cache    map[string]resolveResult
 }
@@ -69,15 +70,19 @@ type resolveResult struct {
 	dgst   digest.Digest
 }
 
-func (imr *imageMetaResolver) ResolveImageConfig(ctx context.Context, ref string) (digest.Digest, []byte, error) {
+func (imr *imageMetaResolver) ResolveImageConfig(ctx context.Context, ref string, platform *specs.Platform) (digest.Digest, []byte, error) {
 	imr.locker.Lock(ref)
 	defer imr.locker.Unlock(ref)
 
 	if res, ok := imr.cache[ref]; ok {
 		return res.dgst, res.config, nil
 	}
 
-	dgst, config, err := imageutil.Config(ctx, ref, imr.resolver, imr.buffer, imr.platform)
+	if platform == nil {
+		platform = imr.platform
+	}
+
+	dgst, config, err := imageutil.Config(ctx, ref, imr.resolver, imr.buffer, platform)
 	if err != nil {
 		return "", nil, err
 	}

diff --git a/client/llb/resolver.go b/client/llb/resolver.go
@@ -4,6 +4,7 @@ import (
 	"context"
 
 	digest "github.com/opencontainers/go-digest"
+	specs "github.com/opencontainers/image-spec/specs-go/v1"
 )
 
 func WithMetaResolver(mr ImageMetaResolver) ImageOption {
@@ -13,5 +14,5 @@ func WithMetaResolver(mr ImageMetaResolver) ImageOption {
 }
 
 type ImageMetaResolver interface {
-	ResolveImageConfig(ctx context.Context, ref string) (digest.Digest, []byte, error)
+	ResolveImageConfig(ctx context.Context, ref string, platform *specs.Platform) (digest.Digest, []byte, error)
 }
diff --git a/client/llb/source.go b/client/llb/source.go
@@ -87,7 +87,7 @@ func Image(ref string, opts ...ImageOption) State {
 		src.err = err
 	}
 	if info.metaResolver != nil {
-		_, dt, err := info.metaResolver.ResolveImageConfig(context.TODO(), ref)
+		_, dt, err := info.metaResolver.ResolveImageConfig(context.TODO(), ref, info.Constraints.Platform)
 		if err != nil {
 			src.err = err
 		} else {

diff --git a/client/llb/state.go b/client/llb/state.go
@@ -36,8 +36,9 @@ func NewState(o Output) State {
 }
 
 type State struct {
-	out Output
-	ctx context.Context
+	out  Output
+	ctx  context.Context
+	opts []ConstraintsOpt
 }
 
 func (s State) ensurePlatform() State {
@@ -62,6 +63,11 @@ func (s State) Value(k interface{}) interface{} {
 	return s.ctx.Value(k)
 }
 
+func (s State) SetMarhalDefaults(co ...ConstraintsOpt) State {
+	s.opts = co
+	return s
+}
+
 func (s State) Marshal(co ...ConstraintsOpt) (*Definition, error) {
 	def := &Definition{
 		Metadata: make(map[digest.Digest]pb.OpMetadata, 0),
@@ -74,7 +80,7 @@ func (s State) Marshal(co ...ConstraintsOpt) (*Definition, error) {
 	c := &Constraints{
 		Platform: &defaultPlatform,
 	}
-	for _, o := range co {
+	for _, o := range append(s.opts, co...) {
 		o.SetConstraintsOption(c)
 	}
 

diff --git a/frontend/dockerfile/builder/build.go b/frontend/dockerfile/builder/build.go
@@ -8,10 +8,12 @@ import (
 	"regexp"
 	"strings"
 
+	"github.com/containerd/containerd/platforms"
 	"github.com/docker/docker/builder/dockerignore"
 	"github.com/moby/buildkit/client/llb"
 	"github.com/moby/buildkit/frontend/dockerfile/dockerfile2llb"
 	"github.com/moby/buildkit/frontend/gateway/client"
+	specs "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/pkg/errors"
 	"golang.org/x/sync/errgroup"
 )
@@ -28,6 +30,7 @@ const (
 	buildArgPrefix        = "build-arg:"
 	labelPrefix           = "label:"
 	keyNoCache            = "no-cache"
+	keyTargetPlatform     = "platform"
 )
 
 var httpPrefix = regexp.MustCompile("^https?://")
@@ -36,6 +39,17 @@ var gitUrlPathWithFragmentSuffix = regexp.MustCompile("\\.git(?:#.+)?$")
 func Build(ctx context.Context, c client.Client) error {
 	opts := c.Opts()
 
+	// TODO: read buildPlatforms from workers
+	buildPlatforms := []specs.Platform{platforms.DefaultSpec()}
+	targetPlatform := platforms.DefaultSpec()
+	if v := opts[keyTargetPlatform]; v != "" {
+		var err error
+		targetPlatform, err = platforms.Parse(v)
+		if err != nil {
+			return errors.Wrapf(err, "failed to parse target platform %s", v)
+		}
+	}
+
 	filename := opts[keyFilename]
 	if filename == "" {
 		filename = defaultDockerfileName
@@ -166,14 +180,16 @@ func Build(ctx context.Context, c client.Client) error {
 	}
 
 	st, img, err := dockerfile2llb.Dockerfile2LLB(ctx, dtDockerfile, dockerfile2llb.ConvertOpt{
-		Target:       opts[keyTarget],
-		MetaResolver: c,
-		BuildArgs:    filter(opts, buildArgPrefix),
-		Labels:       filter(opts, labelPrefix),
-		SessionID:    c.SessionID(),
-		BuildContext: buildContext,
-		Excludes:     excludes,
-		IgnoreCache:  ignoreCache,
+		Target:         opts[keyTarget],
+		MetaResolver:   c,
+		BuildArgs:      filter(opts, buildArgPrefix),
+		Labels:         filter(opts, labelPrefix),
+		SessionID:      c.SessionID(),
+		BuildContext:   buildContext,
+		Excludes:       excludes,
+		IgnoreCache:    ignoreCache,
+		TargetPlatform: &targetPlatform,
+		BuildPlatforms: buildPlatforms,
 	})
 
 	if err != nil {