@@ -113,7 +113,7 @@ func (is *imageSource) resolveLocal(refStr string) ([]byte, error) {

 	return img.RawJSON(), nil

 }

-func (is *imageSource) ResolveImageConfig(ctx context.Context, ref string) (digest.Digest, []byte, error) {

+func (is *imageSource) ResolveImageConfig(ctx context.Context, ref string, platform *ocispec.Platform) (digest.Digest, []byte, error) {

 	if preferLocal {

 		dt, err := is.resolveLocal(ref)

 		if err == nil {

@@ -126,7 +126,7 @@ func (is *imageSource) ResolveImageConfig(ctx context.Context, ref string) (dige

 		dt   []byte

 	}

 	res, err := is.g.Do(ctx, ref, func(ctx context.Context) (interface{}, error) {

-		dgst, dt, err := imageutil.Config(ctx, ref, is.getResolver(ctx), is.ContentStore, nil)

+		dgst, dt, err := imageutil.Config(ctx, ref, is.getResolver(ctx), is.ContentStore, platform)

 		if err != nil {

 			return nil, err

 		}

@@ -145,10 +145,16 @@ func (is *imageSource) Resolve(ctx context.Context, id source.Identifier) (sourc

 		return nil, errors.Errorf("invalid image identifier %v", id)

 	}

+	platform := platforms.DefaultSpec()

+	if imageIdentifier.Platform != nil {

+		platform = *imageIdentifier.Platform

+	}

+

 	p := &puller{

 		src:      imageIdentifier,

 		is:       is,

 		resolver: is.getResolver(ctx),

+		platform: platform,

 	}

 	return p, nil

 }

@@ -163,17 +169,20 @@ type puller struct {

 	resolveErr       error

 	resolver         remotes.Resolver

 	config           []byte

+	platform         ocispec.Platform

 }

-func (p *puller) mainManifestKey(dgst digest.Digest) (digest.Digest, error) {

+func (p *puller) mainManifestKey(dgst digest.Digest, platform ocispec.Platform) (digest.Digest, error) {

 	dt, err := json.Marshal(struct {

-		Digest digest.Digest

-		OS     string

-		Arch   string

+		Digest  digest.Digest

+		OS      string

+		Arch    string

+		Variant string `json:",omitempty"`

 	}{

-		Digest: p.desc.Digest,

-		OS:     runtime.GOOS,

-		Arch:   runtime.GOARCH,

+		Digest:  p.desc.Digest,

+		OS:      platform.OS,

+		Arch:    platform.Architecture,

+		Variant: platform.Variant,

 	})

 	if err != nil {

 		return "", err

@@ -248,7 +257,7 @@ func (p *puller) resolve(ctx context.Context) error {

 				return

 			}

-			_, dt, err := p.is.ResolveImageConfig(ctx, ref.String())

+			_, dt, err := p.is.ResolveImageConfig(ctx, ref.String(), &p.platform)

 			if err != nil {

 				p.resolveErr = err

 				resolveProgressDone(err)

@@ -266,7 +275,7 @@ func (p *puller) CacheKey(ctx context.Context, index int) (string, bool, error)

 	p.resolveLocal()

 	if p.desc.Digest != "" && index == 0 {

-		dgst, err := p.mainManifestKey(p.desc.Digest)

+		dgst, err := p.mainManifestKey(p.desc.Digest, p.platform)

 		if err != nil {

 			return "", false, err

 		}

@@ -282,7 +291,7 @@ func (p *puller) CacheKey(ctx context.Context, index int) (string, bool, error)

 	}

 	if p.desc.Digest != "" && index == 0 {

-		dgst, err := p.mainManifestKey(p.desc.Digest)

+		dgst, err := p.mainManifestKey(p.desc.Digest, p.platform)

 		if err != nil {

 			return "", false, err

 		}

@@ -9,6 +9,7 @@ import (

 	"time"

 	"github.com/containerd/containerd/content"

+	"github.com/containerd/containerd/platforms"

 	"github.com/docker/docker/api/types"

 	"github.com/docker/docker/api/types/backend"

 	"github.com/docker/docker/builder"

@@ -208,6 +209,10 @@ func (b *Builder) Build(ctx context.Context, opt backend.BuildConfig) (*builder.

 		frontendAttrs["no-cache"] = ""

 	}

+	if opt.Options.Platform != nil {

+		frontendAttrs["platform"] = platforms.Format(*opt.Options.Platform)

+	}

+

 	exporterAttrs := map[string]string{}

 	if len(opt.Options.Tags) > 0 {