@@ -42,8 +42,6 @@ import (

 	"golang.org/x/time/rate"

 )

-const preferLocal = true // FIXME: make this optional from the op

-

 // SourceOpt is options for creating the image source

 type SourceOpt struct {

 	SessionManager  *session.Manager

@@ -114,32 +112,61 @@ func (is *imageSource) resolveLocal(refStr string) ([]byte, error) {

 	return img.RawJSON(), nil

 }

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

-	if preferLocal {

-		dt, err := is.resolveLocal(ref)

-		if err == nil {

-			return "", dt, nil

-		}

-	}

-

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

 	type t struct {

 		dgst digest.Digest

 		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, opt.Platform)

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

 		if err != nil {

 			return nil, err

 		}

 		return &t{dgst: dgst, dt: dt}, nil

 	})

+	var typed *t

 	if err != nil {

 		return "", nil, err

 	}

-	typed := res.(*t)

+	typed = res.(*t)

 	return typed.dgst, typed.dt, nil

 }

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

+	resolveMode, err := source.ParseImageResolveMode(opt.ResolveMode)

+	if err != nil {

+		return "", nil, err

+	}

+	switch resolveMode {

+	case source.ResolveModeForcePull:

+		dgst, dt, err := is.resolveRemote(ctx, ref, opt.Platform)

+		// TODO: pull should fallback to local in case of failure to allow offline behavior

+		// the fallback doesn't work currently

+		return dgst, dt, err

+		/*

+			if err == nil {

+				return dgst, dt, err

+			}

+			// fallback to local

+			dt, err = is.resolveLocal(ref)

+			return "", dt, err

+		*/

+

+	case source.ResolveModeDefault:

+		// default == prefer local, but in the future could be smarter

+		fallthrough

+	case source.ResolveModePreferLocal:

+		dt, err := is.resolveLocal(ref)

+		if err == nil {

+			return "", dt, err

+		}

+		// fallback to remote

+		return is.resolveRemote(ctx, ref, opt.Platform)

+	}

+	// should never happen

+	return "", nil, fmt.Errorf("builder cannot resolve image %s: invalid mode %q", ref, opt.ResolveMode)

+}

+

 func (is *imageSource) Resolve(ctx context.Context, id source.Identifier) (source.SourceInstance, error) {

 	imageIdentifier, ok := id.(*source.ImageIdentifier)

 	if !ok {

@@ -213,7 +240,7 @@ func (p *puller) resolveLocal() {

 			}

 		}

-		if preferLocal {

+		if p.src.ResolveMode == source.ResolveModeDefault || p.src.ResolveMode == source.ResolveModePreferLocal {

 			dt, err := p.is.resolveLocal(p.src.Reference.String())

 			if err == nil {

 				p.config = dt

@@ -257,8 +284,7 @@ func (p *puller) resolve(ctx context.Context) error {

 				resolveProgressDone(err)

 				return

 			}

-

-			_, dt, err := p.is.ResolveImageConfig(ctx, ref.String(), gw.ResolveImageConfigOpt{Platform: &p.platform})

+			_, dt, err := p.is.ResolveImageConfig(ctx, ref.String(), gw.ResolveImageConfigOpt{Platform: &p.platform, ResolveMode: resolveModeToString(p.src.ResolveMode)})

 			if err != nil {

 				p.resolveErr = err

 				resolveProgressDone(err)

@@ -732,3 +758,17 @@ func cacheKeyFromConfig(dt []byte) digest.Digest {

 	}

 	return identity.ChainID(img.RootFS.DiffIDs)

 }

+

+// resolveModeToString is the equivalent of github.com/moby/buildkit/solver/llb.ResolveMode.String()

+// FIXME: add String method on source.ResolveMode

+func resolveModeToString(rm source.ResolveMode) string {

+	switch rm {

+	case source.ResolveModeDefault:

+		return "default"

+	case source.ResolveModeForcePull:

+		return "pull"

+	case source.ResolveModePreferLocal:

+		return "local"

+	}

+	return ""

+}

@@ -209,6 +209,12 @@ func (b *Builder) Build(ctx context.Context, opt backend.BuildConfig) (*builder.

 		frontendAttrs["no-cache"] = ""

 	}

+	if opt.Options.PullParent {

+		frontendAttrs["image-resolve-mode"] = "pull"

+	} else {

+		frontendAttrs["image-resolve-mode"] = "default"

+	}

+

 	if opt.Options.Platform != "" {

 		// same as in newBuilder in builder/dockerfile.builder.go

 		// TODO: remove once opt.Options.Platform is of type specs.Platform