bake: update ReadRemoteFiles to use buildkit api

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/github.com/moby/buildkit/frontend/dockerui/build.go

@@ -0,0 +1,114 @@
+package dockerui
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"github.com/containerd/containerd/platforms"
+	"github.com/moby/buildkit/exporter/containerimage/exptypes"
+	"github.com/moby/buildkit/exporter/containerimage/image"
+	"github.com/moby/buildkit/frontend/gateway/client"
+	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/pkg/errors"
+	"golang.org/x/sync/errgroup"
+)
+
+type BuildFunc func(ctx context.Context, platform *ocispecs.Platform, idx int) (client.Reference, *image.Image, error)
+
+func (bc *Client) Build(ctx context.Context, fn BuildFunc) (*ResultBuilder, error) {
+	res := client.NewResult()
+
+	targets := make([]*ocispecs.Platform, 0, len(bc.TargetPlatforms))
+	for _, p := range bc.TargetPlatforms {
+		p := p
+		targets = append(targets, &p)
+	}
+	if len(targets) == 0 {
+		targets = append(targets, nil)
+	}
+	expPlatforms := &exptypes.Platforms{
+		Platforms: make([]exptypes.Platform, len(targets)),
+	}
+
+	eg, ctx := errgroup.WithContext(ctx)
+
+	for i, tp := range targets {
+		i, tp := i, tp
+		eg.Go(func() error {
+			ref, img, err := fn(ctx, tp, i)
+			if err != nil {
+				return err
+			}
+
+			config, err := json.Marshal(img)
+			if err != nil {
+				return errors.Wrapf(err, "failed to marshal image config")
+			}
+
+			p := platforms.DefaultSpec()
+			if tp != nil {
+				p = *tp
+			}
+
+			// in certain conditions we allow input platform to be extended from base image
+			if p.OS == "windows" && img.OS == p.OS {
+				if p.OSVersion == "" && img.OSVersion != "" {
+					p.OSVersion = img.OSVersion
+				}
+				if p.OSFeatures == nil && len(img.OSFeatures) > 0 {
+					p.OSFeatures = img.OSFeatures
+				}
+			}
+
+			p = platforms.Normalize(p)
+			k := platforms.Format(p)
+
+			if bc.MultiPlatformRequested {
+				res.AddRef(k, ref)
+				res.AddMeta(fmt.Sprintf("%s/%s", exptypes.ExporterImageConfigKey, k), config)
+			} else {
+				res.SetRef(ref)
+				res.AddMeta(exptypes.ExporterImageConfigKey, config)
+			}
+			expPlatforms.Platforms[i] = exptypes.Platform{
+				ID:       k,
+				Platform: p,
+			}
+			return nil
+		})
+	}
+	if err := eg.Wait(); err != nil {
+		return nil, err
+	}
+	return &ResultBuilder{
+		Result:       res,
+		expPlatforms: expPlatforms,
+	}, nil
+}
+
+type ResultBuilder struct {
+	*client.Result
+	expPlatforms *exptypes.Platforms
+}
+
+func (rb *ResultBuilder) Finalize() (*client.Result, error) {
+	dt, err := json.Marshal(rb.expPlatforms)
+	if err != nil {
+		return nil, err
+	}
+	rb.AddMeta(exptypes.ExporterPlatformsKey, dt)
+
+	return rb.Result, nil
+}
+
+func (rb *ResultBuilder) EachPlatform(ctx context.Context, fn func(ctx context.Context, id string, p ocispecs.Platform) error) error {
+	eg, ctx := errgroup.WithContext(ctx)
+	for _, p := range rb.expPlatforms.Platforms {
+		p := p
+		eg.Go(func() error {
+			return fn(ctx, p.ID, p.Platform)
+		})
+	}
+	return eg.Wait()
+}