nomad: expose the raft index on write

nomad/client_endpoint.go

@@ -40,10 +40,17 @@ func (c *Client) Register(args *structs.RegisterRequest, reply *structs.GenericR
 	}
 
 	// Commit this update via Raft
-	_, err := c.srv.raftApply(structs.RegisterRequestType, args)
+	_, index, err := c.srv.raftApply(structs.RegisterRequestType, args)
 	if err != nil {
 		c.srv.logger.Printf("[ERR] nomad.client: Register failed: %v", err)
 		return err
 	}
+
+	// Set the reply index
+	reply.Index = index
+	return nil
+}
+
+func (c *Client) Deregister(args *structs.DeregisterRequest, reply *structs.GenericResponse) error {
 	return nil
 }

nomad/client_endpoint_test.go

@@ -26,6 +26,9 @@ func TestClientEndpoint_Register(t *testing.T) {
 	if err := msgpackrpc.CallWithCodec(codec, "Client.Register", req, &resp); err != nil {
 		t.Fatalf("err: %v", err)
 	}
+	if resp.Index == 0 {
+		t.Fatalf("bad index: %d", resp.Index)
+	}
 
 	// Check for the node in the FSM
 	state := s1.fsm.State()
@@ -36,4 +39,7 @@ func TestClientEndpoint_Register(t *testing.T) {
 	if out == nil {
 		t.Fatalf("expected node")
 	}
+	if out.CreateIndex != resp.Index {
+		t.Fatalf("index mis-match")
+	}
 }

nomad/rpc.go

@@ -236,10 +236,10 @@ func (s *Server) forwardRegion(region, method string, args interface{}, reply in
 
 // raftApply is used to encode a message, run it through raft, and return
 // the FSM response along with any errors
-func (s *Server) raftApply(t structs.MessageType, msg interface{}) (interface{}, error) {
+func (s *Server) raftApply(t structs.MessageType, msg interface{}) (interface{}, uint64, error) {
 	buf, err := structs.Encode(t, msg)
 	if err != nil {
-		return nil, fmt.Errorf("Failed to encode request: %v", err)
+		return nil, 0, fmt.Errorf("Failed to encode request: %v", err)
 	}
 
 	// Warn if the command is very large
@@ -249,8 +249,8 @@ func (s *Server) raftApply(t structs.MessageType, msg interface{}) (interface{},
 
 	future := s.raft.Apply(buf, enqueueLimit)
 	if err := future.Error(); err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 
-	return future.Response(), nil
+	return future.Response(), future.Index(), nil
 }