Merge pull request #1433 from hinshun/session-hijack

Allow sessions to hijack the connection outside of a solve

client/client.go

@@ -11,6 +11,8 @@ import (
 	"github.com/grpc-ecosystem/grpc-opentracing/go/otgrpc"
 	controlapi "github.com/moby/buildkit/api/services/control"
 	"github.com/moby/buildkit/client/connhelper"
+	"github.com/moby/buildkit/session"
+	"github.com/moby/buildkit/session/grpchijack"
 	"github.com/moby/buildkit/util/appdefaults"
 	opentracing "github.com/opentracing/opentracing-go"
 	"github.com/pkg/errors"
@@ -80,6 +82,10 @@ func (c *Client) controlClient() controlapi.ControlClient {
 	return controlapi.NewControlClient(c.conn)
 }
 
+func (c *Client) Dialer() session.Dialer {
+	return grpchijack.Dialer(c.controlClient())
+}
+
 func (c *Client) Close() error {
 	return c.conn.Close()
 }

client/solve.go

@@ -115,6 +115,12 @@ func (c *Client) solve(ctx context.Context, def *llb.Definition, runGateway runG
 	}
 
 	var ex ExportEntry
+	if len(opt.Exports) > 1 {
+		return nil, errors.New("currently only single Exports can be specified")
+	}
+	if len(opt.Exports) == 1 {
+		ex = opt.Exports[0]
+	}
 
 	if !opt.SessionPreInitialized {
 		if len(syncedDirs) > 0 {
@@ -125,13 +131,6 @@ func (c *Client) solve(ctx context.Context, def *llb.Definition, runGateway runG
 			s.Allow(a)
 		}
 
-		if len(opt.Exports) > 1 {
-			return nil, errors.New("currently only single Exports can be specified")
-		}
-		if len(opt.Exports) == 1 {
-			ex = opt.Exports[0]
-		}
-
 		switch ex.Type {
 		case ExporterLocal:
 			if ex.Output != nil {