From 7562a6638ac7552170c275c4d6dcfa1946df496c Mon Sep 17 00:00:00 2001
From: Edgar Lee <edgarl@netflix.com>
Date: Thu, 5 Dec 2019 11:08:12 -0800
Subject: [PATCH] Fix empty string id in result ref

Signed-off-by: Edgar Lee <edgarl@netflix.com>
---
 frontend/gateway/gateway.go           | 4 ++--
 frontend/gateway/grpcclient/client.go | 4 ++--
 frontend/gateway/pb/ref.go            | 9 +++++++++
 3 files changed, 13 insertions(+), 4 deletions(-)
 create mode 100644 frontend/gateway/pb/ref.go

diff --git a/frontend/gateway/gateway.go b/frontend/gateway/gateway.go
index 3727b98e..392ee261 100644
--- a/frontend/gateway/gateway.go
+++ b/frontend/gateway/gateway.go
@@ -479,7 +479,7 @@ func (lbf *llbBridgeForwarder) Solve(ctx context.Context, req *pb.SolveRequest)
 		if req.AllowResultArrayRef {
 			refMap := make(map[string]*pb.Ref, len(res.Refs))
 			for k, id := range ids {
-				refMap[k] = &pb.Ref{Ids: []string{id}}
+				refMap[k] = pb.NewRef(id)
 			}
 			pbRes.Result = &pb.Result_Refs{Refs: &pb.RefMap{Refs: refMap}}
 		} else {
@@ -495,7 +495,7 @@ func (lbf *llbBridgeForwarder) Solve(ctx context.Context, req *pb.SolveRequest)
 		defaultID = id
 
 		if req.AllowResultArrayRef {
-			pbRes.Result = &pb.Result_Ref{Ref: &pb.Ref{Ids: []string{id}}}
+			pbRes.Result = &pb.Result_Ref{Ref: pb.NewRef(id)}
 		} else {
 			pbRes.Result = &pb.Result_RefDeprecated{RefDeprecated: id}
 		}
diff --git a/frontend/gateway/grpcclient/client.go b/frontend/gateway/grpcclient/client.go
index ae1eaab5..b7dba2b7 100644
--- a/frontend/gateway/grpcclient/client.go
+++ b/frontend/gateway/grpcclient/client.go
@@ -112,7 +112,7 @@ func (c *grpcClient) Run(ctx context.Context, f client.BuildFunc) (retError erro
 							retError = err
 							continue
 						}
-						m[k] = &pb.Ref{Ids: []string{id}}
+						m[k] = pb.NewRef(id)
 					}
 					pbRes.Result = &pb.Result_Refs{Refs: &pb.RefMap{Refs: m}}
 				} else {
@@ -120,7 +120,7 @@ func (c *grpcClient) Run(ctx context.Context, f client.BuildFunc) (retError erro
 					if err != nil {
 						retError = err
 					} else {
-						pbRes.Result = &pb.Result_Ref{Ref: &pb.Ref{Ids: []string{id}}}
+						pbRes.Result = &pb.Result_Ref{Ref: pb.NewRef(id)}
 					}
 				}
 				if retError == nil {
diff --git a/frontend/gateway/pb/ref.go b/frontend/gateway/pb/ref.go
new file mode 100644
index 00000000..882fae57
--- /dev/null
+++ b/frontend/gateway/pb/ref.go
@@ -0,0 +1,9 @@
+package moby_buildkit_v1_frontend
+
+func NewRef(id string) *Ref {
+	var ref Ref
+	if id != "" {
+		ref.Ids = append(ref.Ids, id)
+	}
+	return &ref
+}