bake: update ReadRemoteFiles to use buildkit api

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

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

@@ -0,0 +1,91 @@
+package dockerui
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+
+	"github.com/moby/buildkit/frontend/gateway/client"
+	"github.com/moby/buildkit/frontend/subrequests"
+	"github.com/moby/buildkit/frontend/subrequests/outline"
+	"github.com/moby/buildkit/frontend/subrequests/targets"
+	"github.com/moby/buildkit/solver/errdefs"
+)
+
+const (
+	keyRequestID = "requestid"
+)
+
+type RequestHandler struct {
+	Outline     func(context.Context) (*outline.Outline, error)
+	ListTargets func(context.Context) (*targets.List, error)
+	AllowOther  bool
+}
+
+func (bc *Client) HandleSubrequest(ctx context.Context, h RequestHandler) (*client.Result, bool, error) {
+	req, ok := bc.bopts.Opts[keyRequestID]
+	if !ok {
+		return nil, false, nil
+	}
+	switch req {
+	case subrequests.RequestSubrequestsDescribe:
+		res, err := describe(h)
+		return res, true, err
+	case outline.SubrequestsOutlineDefinition.Name:
+		if f := h.Outline; f != nil {
+			o, err := f(ctx)
+			if err != nil {
+				return nil, false, err
+			}
+			if o == nil {
+				return nil, true, nil
+			}
+			res, err := o.ToResult()
+			return res, true, err
+		}
+	case targets.SubrequestsTargetsDefinition.Name:
+		if f := h.ListTargets; f != nil {
+			targets, err := f(ctx)
+			if err != nil {
+				return nil, false, err
+			}
+			if targets == nil {
+				return nil, true, nil
+			}
+			res, err := targets.ToResult()
+			return res, true, err
+		}
+	}
+	if h.AllowOther {
+		return nil, false, nil
+	}
+	return nil, false, errdefs.NewUnsupportedSubrequestError(req)
+}
+
+func describe(h RequestHandler) (*client.Result, error) {
+	all := []subrequests.Request{}
+	if h.Outline != nil {
+		all = append(all, outline.SubrequestsOutlineDefinition)
+	}
+	if h.ListTargets != nil {
+		all = append(all, targets.SubrequestsTargetsDefinition)
+	}
+	all = append(all, subrequests.SubrequestsDescribeDefinition)
+	dt, err := json.MarshalIndent(all, "", "  ")
+	if err != nil {
+		return nil, err
+	}
+
+	b := bytes.NewBuffer(nil)
+	if err := subrequests.PrintDescribe(dt, b); err != nil {
+		return nil, err
+	}
+
+	res := client.NewResult()
+	res.Metadata = map[string][]byte{
+		"result.json": dt,
+		"result.txt":  b.Bytes(),
+		"version":     []byte(subrequests.SubrequestsDescribeDefinition.Version),
+	}
+	return res, nil
+}