feat: Implement agent heartbeat with mTLS and node status tracking

cmd/kat-agent/main.go

@@ -265,6 +265,10 @@ func runInit(cmd *cobra.Command, args []string) {
 				joinHandler := api.NewJoinHandler(etcdStore, caKeyPath, caCertPath)
 				apiServer.RegisterJoinHandler(joinHandler)
 				log.Printf("Registered join handler with CA key: %s, CA cert: %s", caKeyPath, caCertPath)
+		
+				// Register the node status handler
+				nodeStatusHandler := api.NewNodeStatusHandler(etcdStore)
+				apiServer.RegisterNodeStatusHandler(nodeStatusHandler)
 
 				// Start the server in a goroutine
 				go func() {
@@ -333,7 +337,8 @@ func runJoin(cmd *cobra.Command, args []string) {
 	pkiDir := filepath.Join(os.Getenv("HOME"), ".kat-agent", nodeName, "pki")
 
 	// Join the cluster
-	if err := cli.JoinCluster(leaderAPI, advertiseAddr, nodeName, leaderCACert, pkiDir); err != nil {
+	joinResp, err := cli.JoinCluster(leaderAPI, advertiseAddr, nodeName, leaderCACert, pkiDir)
+	if err != nil {
 		log.Fatalf("Failed to join cluster: %v", err)
 	}
 
@@ -343,20 +348,36 @@ func runJoin(cmd *cobra.Command, args []string) {
 	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
 	defer stop()
 	
-	// Stay up in an idle loop until interrupted
-	log.Printf("Node %s is now running. Press Ctrl+C to exit.", nodeName)
-	ticker := time.NewTicker(30 * time.Second)
-	defer ticker.Stop()
-	
-	for {
-		select {
-		case <-ctx.Done():
-			log.Println("Received shutdown signal. Exiting...")
-			return
-		case <-ticker.C:
-			log.Printf("Node %s is still running...", nodeName)
-		}
+	// Create and start the agent with heartbeating
+	agent, err := agent.NewAgent(
+		joinResp.NodeName,
+		joinResp.NodeUID,
+		leaderAPI,
+		advertiseAddr,
+		pkiDir,
+		15, // Default heartbeat interval in seconds
+	)
+	if err != nil {
+		log.Fatalf("Failed to create agent: %v", err)
 	}
+	
+	// Setup mTLS client
+	if err := agent.SetupMTLSClient(); err != nil {
+		log.Fatalf("Failed to setup mTLS client: %v", err)
+	}
+	
+	// Start heartbeating
+	if err := agent.StartHeartbeat(ctx); err != nil {
+		log.Fatalf("Failed to start heartbeat: %v", err)
+	}
+	
+	log.Printf("Node %s is now running with heartbeat. Press Ctrl+C to exit.", nodeName)
+	
+	// Wait for shutdown signal
+	<-ctx.Done()
+	log.Println("Received shutdown signal. Stopping heartbeat...")
+	agent.StopHeartbeat()
+	log.Println("Exiting...")
 }
 
 func runVerify(cmd *cobra.Command, args []string) {