feat: wire MODE config to select compose or swarm discovery/executor

cmd/server/main.go

@@ -42,7 +42,7 @@ func run() error {
 	logger := logging.New(cfg.LogLevel)
 	logger.Info("starting",
 		"version", version, "commit", commit, "port", cfg.Port,
-		"stacks_root", cfg.StacksRoot, "opt_in_label", cfg.OptInLabel,
+		"mode", cfg.Mode, "stacks_root", cfg.StacksRoot, "opt_in_label", cfg.OptInLabel,
 	)
 
 	dockerCli, err := client.NewClientWithOpts(client.FromEnv, client.WithAPIVersionNegotiation())
@@ -51,8 +51,21 @@ func run() error {
 	}
 	defer dockerCli.Close()
 
-	disc := discovery.New(dockerCli, cfg.StacksRoot, cfg.OptInLabel)
-	exec := updater.NewComposeExecutor()
+	var finder api.Finder
+	var exec updater.Executor
+	switch cfg.Mode {
+	case "swarm":
+		finder = discovery.NewSwarm(dockerCli, cfg.OptInLabel)
+		exec = updater.NewSwarmExecutor(dockerCli)
+	case "compose":
+		finder = discovery.New(dockerCli, cfg.StacksRoot, cfg.OptInLabel)
+		exec = updater.NewComposeExecutor()
+	default:
+		// Unreachable: config.Load already validates Mode, but guard
+		// here too rather than silently falling through to a nil
+		// finder/exec pair.
+		return fmt.Errorf("unknown MODE %q", cfg.Mode)
+	}
 
 	reg := prometheus.NewRegistry()
 	m := metrics.New(reg)
@@ -62,7 +75,7 @@ func run() error {
 	queue.Start(context.Background())
 	defer queue.Stop()
 
-	handlers := api.NewHandlers(disc, &submitterAdapter{queue: queue, timeout: cfg.UpdateTimeout}, dockerCli, version, commit, buildTime, m)
+	handlers := api.NewHandlers(finder, &submitterAdapter{queue: queue, timeout: cfg.UpdateTimeout}, dockerCli, version, commit, buildTime, m)
 
 	mux := http.NewServeMux()
 	mux.HandleFunc("POST /update", handlers.Update)