feat: agents connect by WebSocket, falling back to long polling and trying again each minute; auto, ws or lp per machine (0.1.0)

internal/server/handlers_agent.go

@@ -53,8 +53,9 @@ func (s *Server) handlePoll(w http.ResponseWriter, r *http.Request) {
 		_ = s.db.TouchAgent(a.ID)
 	}
 	msg := s.hub.WaitControl(r.Context().Done(), a.ID, pollHold)
-	// Set after the hold so a port changed meanwhile reaches the agent now.
+	// Set after the hold so a setting changed meanwhile reaches the agent now.
 	s.setTunnelHeader(w)
+	w.Header().Set(proto.TransportHeader, s.transportOf(a.ID))
 	writeJSON(w, msg)
 }
 
@@ -71,11 +72,13 @@ func (s *Server) setTunnelHeader(w http.ResponseWriter) {
 // GET /api/agent/config - settings an agent picks up when it connects, without
 // waiting out a poll hold.
 func (s *Server) handleAgentConfig(w http.ResponseWriter, r *http.Request) {
-	if s.authenticateAgent(r) == nil {
+	a := s.authenticateAgent(r)
+	if a == nil {
 		http.Error(w, "unauthorized", http.StatusUnauthorized)
 		return
 	}
 	s.setTunnelHeader(w)
+	w.Header().Set(proto.TransportHeader, s.transportOf(a.ID))
 	w.WriteHeader(http.StatusNoContent)
 }