dockerfile: use fileop for http context

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

frontend/dockerfile/builder/build.go

@@ -20,6 +20,7 @@ import (
 	"github.com/moby/buildkit/frontend/dockerfile/dockerfile2llb"
 	"github.com/moby/buildkit/frontend/gateway/client"
 	"github.com/moby/buildkit/solver/pb"
+	"github.com/moby/buildkit/util/apicaps"
 	specs "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/pkg/errors"
 	"golang.org/x/sync/errgroup"
@@ -151,6 +152,13 @@ func Build(ctx context.Context, c client.Client) (*client.Result, error) {
 			return nil, errors.Errorf("failed to read downloaded context")
 		}
 		if isArchive(dt) {
+			fileop := useFileOp(opts, &caps)
+			if fileop {
+				src = llb.Scratch().File(llb.Copy(httpContext, "/context", "/", &llb.CopyInfo{
+					AttemptUnpack: true,
+				}))
+				buildContext = &src
+			} else {
 				copyImage := opts[keyOverrideCopyImage]
 				if copyImage == "" {
 					copyImage = dockerfile2llb.DefaultCopyImage
@@ -160,6 +168,7 @@ func Build(ctx context.Context, c client.Client) (*client.Result, error) {
 				unpack.AddMount("/src", httpContext, llb.Readonly)
 				src = unpack.AddMount("/out", llb.Scratch())
 				buildContext = &src
+			}
 		} else {
 			filename = "context"
 			src = httpContext
@@ -529,3 +538,13 @@ func parseNetMode(v string) (pb.NetMode, error) {
 		return 0, errors.Errorf("invalid netmode %s", v)
 	}
 }
+
+func useFileOp(args map[string]string, caps *apicaps.CapSet) bool {
+	enabled := true
+	if v, ok := args["build-arg:BUILDKIT_DISABLE_FILEOP"]; ok {
+		if b, err := strconv.ParseBool(v); err == nil {
+			enabled = !b
+		}
+	}
+	return enabled && caps != nil && caps.Supports(pb.CapFileBase) == nil
+}

session/upload/upload.go

@@ -16,8 +16,8 @@ const (
 
 func New(ctx context.Context, c session.Caller, url *url.URL) (*Upload, error) {
 	opts := map[string][]string{
-		keyPath: []string{url.Path},
-		keyHost: []string{url.Host},
+		keyPath: {url.Path},
+		keyHost: {url.Host},
 	}
 
 	client := NewUploadClient(c.Conn())