Return listenbuffer behavior

Now we're start to serve early, but all Accept calls are intercepted by
listenbuffer or systemd socket.

Signed-off-by: Alexander Morozov <lk4d4@docker.com>

api/server/server.go

@@ -76,11 +76,10 @@ func (s *Server) Close() {
 }
 
 // ServeAPI loops through all initialized servers and spawns goroutine
-// with Server method for each. It sets CreateMux() as Handler also.
+// with Serve() method for each.
 func (s *Server) ServeAPI() error {
 	var chErrors = make(chan error, len(s.servers))
 	for _, srv := range s.servers {
-		srv.srv.Handler = s.CreateMux()
 		go func(srv *HTTPServer) {
 			var err error
 			logrus.Infof("API listen on %s", srv.l.Addr())
@@ -162,9 +161,13 @@ func (s *Server) makeHTTPHandler(handler httputils.APIFunc) http.HandlerFunc {
 }
 
 // InitRouters initializes a list of routers for the server.
+// Sets those routers as Handler for each server.
 func (s *Server) InitRouters(d *daemon.Daemon) {
 	s.addRouter(local.NewRouter(d))
 	s.addRouter(network.NewRouter(d))
+	for _, srv := range s.servers {
+		srv.srv.Handler = s.CreateMux()
+	}
 }
 
 // addRouter adds a new router to the server.

docker/daemon.go

@@ -235,6 +235,21 @@ func (cli *DaemonCli) CmdDaemon(args ...string) error {
 		logrus.Fatal(err)
 	}
 
+	// The serve API routine never exits unless an error occurs
+	// We need to start it as a goroutine and wait on it so
+	// daemon doesn't exit
+	// All servers must be protected with some mechanism (systemd socket, listenbuffer)
+	// which prevents real handling of request until routes will be set.
+	serveAPIWait := make(chan error)
+	go func() {
+		if err := api.ServeAPI(); err != nil {
+			logrus.Errorf("ServeAPI error: %v", err)
+			serveAPIWait <- err
+			return
+		}
+		serveAPIWait <- nil
+	}()
+
 	if err := migrateKey(); err != nil {
 		logrus.Fatal(err)
 	}
@@ -262,19 +277,6 @@ func (cli *DaemonCli) CmdDaemon(args ...string) error {
 
 	api.InitRouters(d)
 
-	// The serve API routine never exits unless an error occurs
-	// We need to start it as a goroutine and wait on it so
-	// daemon doesn't exit
-	serveAPIWait := make(chan error)
-	go func() {
-		if err := api.ServeAPI(); err != nil {
-			logrus.Errorf("ServeAPI error: %v", err)
-			serveAPIWait <- err
-			return
-		}
-		serveAPIWait <- nil
-	}()
-
 	signal.Trap(func() {
 		api.Close()
 		<-serveAPIWait