Use new field nextRaftId to give unique IDs to new nodes.

dgraph/cmd/zero/zero.go

@@ -56,6 +56,7 @@ type Server struct {
 
 	NumReplicas int
 	state       *pb.MembershipState
+	nextRaftId  uint64
 
 	nextLeaseId uint64
 	nextTxnTs   uint64
@@ -83,6 +84,7 @@ func (s *Server) Init() {
 		Groups: make(map[uint32]*pb.Group),
 		Zeros:  make(map[uint64]*pb.Member),
 	}
+	s.nextRaftId = 1
 	s.nextLeaseId = 1
 	s.nextTxnTs = 1
 	s.nextGroup = 1
@@ -217,7 +219,10 @@ func (s *Server) hasLeader(gid uint32) bool {
 func (s *Server) SetMembershipState(state *pb.MembershipState) {
 	s.Lock()
 	defer s.Unlock()
+
 	s.state = state
+	s.nextRaftId = x.Max(s.nextRaftId, s.state.MaxRaftId + 1)
+
 	if state.Zeros == nil {
 		state.Zeros = make(map[uint64]*pb.Member)
 	}
@@ -491,7 +496,8 @@ func (s *Server) Connect(ctx context.Context,
 			}
 		}
 		if m.Id == 0 {
-			m.Id = s.state.MaxRaftId + 1
+			m.Id = s.nextRaftId
+			s.nextRaftId += 1
 			proposal.MaxRaftId = m.Id
 		}