Reengineered code.

.gitignore

@@ -1,2 +1,3 @@
 .vscode
 build
+netbox-dns-updater

build-linux.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+set -e
+
+ARCH=amd64
+BIN_NAME="netbox-dns-updater-linux-$ARCH"
+
+# Build optimized binary and strip debug symbols
+echo "Building optimized netbox-dns-updater for linux/$ARCH..."
+GOOS=linux GOARCH=$ARCH go build -ldflags="-s -w" -o build/$BIN_NAME netbox-dns-updater.go
+echo "Build complete: build/$BIN_NAME (optimized and stripped)"

build.sh

@@ -1,3 +0,0 @@
-#!/bin/sh
-test -d build || mkdir -p build
-GOOS=linux GOARCH=amd64 go build -ldflags="-s -w" -o build/netbox-dns-updater

netbox-dns-updater.go

@@ -61,7 +61,94 @@ func FetchNetboxIPAddresses(apiBaseURL, token string) ([]IPAddress, error) {
 	return filtered, nil
 }
 
-func CreateDnsMasqConfig(writeConfig bool) {
+var apiBaseURL string
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Fprintf(os.Stderr, "Usage: %s <run|serve> [flags]\n", os.Args[0])
+		os.Exit(1)
+	}
+
+	subCmd := os.Args[1]
+	// Prepare a FlagSet for subcommands, sharing the same flags
+	flags := flag.NewFlagSet(subCmd, flag.ExitOnError)
+
+	var apiURL string
+	var outputFormat string
+	var outputFile string
+	var outputDir string
+	var dryRun bool
+	var listenAddr string
+
+	flags.StringVar(&apiURL, "api-url", "https://netbox.koszewscy.waw.pl/api", "NetBox API URL to fetch IP addresses")
+	flags.StringVar(&outputFormat, "output-format", "hosts", "output format: config or hosts")
+	flags.StringVar(&outputFile, "output-file", "", "output file name (overrides default)")
+	flags.StringVar(&outputDir, "output-dir", "", "output base directory (overrides default)")
+	flags.BoolVar(&dryRun, "dry-run", false, "if set, do not write to dnsmasq config file, just print the output")
+	flags.StringVar(&listenAddr, "listen", ":8080", "address and port to listen on (e.g. :8080 or 127.0.0.1:8080)")
+
+	flags.Parse(os.Args[2:])
+	apiBaseURL = apiURL
+
+	// Set defaults based on output format
+	var defaultDir, defaultFile string
+	switch outputFormat {
+	case "hosts":
+		defaultDir = "/etc"
+		defaultFile = "hosts.netbox"
+	case "config":
+		defaultDir = "/etc/dnsmasq.d"
+		defaultFile = "netbox.conf"
+	default:
+		log.Fatalf("Unknown output format: %s", outputFormat)
+	}
+	dir := defaultDir
+	file := defaultFile
+	if outputDir != "" {
+		dir = outputDir
+	}
+	if outputFile != "" {
+		file = outputFile
+	}
+
+	switch subCmd {
+	case "run":
+		if listenAddr != ":8080" && listenAddr != "" {
+			log.Fatalf("The --listen flag is only valid with the 'serve' subcommand.")
+		}
+		if dryRun {
+			log.Println("Dry run mode enabled, not writing to dnsmasq config file.")
+			CreateDnsMasqConfig(true, outputFormat, dir, file)
+		} else {
+			CreateDnsMasqConfig(false, outputFormat, dir, file)
+		}
+	case "serve":
+		http.HandleFunc("/update-dnsmasq", func(w http.ResponseWriter, r *http.Request) {
+			if r.Method != http.MethodGet {
+				w.WriteHeader(http.StatusMethodNotAllowed)
+				w.Write([]byte("Method not allowed"))
+				return
+			}
+			CreateDnsMasqConfig(false, outputFormat, dir, file)
+			cmd := exec.Command("systemctl", "restart", "dnsmasq.service")
+			if err := cmd.Run(); err != nil {
+				log.Printf("Failed to restart dnsmasq.service: %v", err)
+				w.Write([]byte("\nWarning: Failed to restart dnsmasq.service.\n"))
+			}
+			w.Write([]byte("DNSMasq config updated."))
+		})
+		log.Printf("Starting web service on %s...", listenAddr)
+		if err := http.ListenAndServe(listenAddr, nil); err != nil {
+			log.Fatalf("Failed to start server: %v", err)
+		}
+	default:
+		fmt.Fprintf(os.Stderr, "Unknown subcommand: %s\n", subCmd)
+		os.Exit(1)
+	}
+}
+
+// Update CreateDnsMasqConfig to accept new parameters
+func CreateDnsMasqConfig(writeConfig bool, outputFormat, dir, file string) {
 	token := os.Getenv("NETBOX_TOKEN")
 	if token == "" {
 		home := os.Getenv("HOME")
@@ -86,53 +173,26 @@ func CreateDnsMasqConfig(writeConfig bool) {
 		log.Fatalf("Error fetching IP addresses: %v", err)
 	}
 
-	dir := "/etc/dnsmasq.d"
 	if stat, err := os.Stat(dir); err == nil && stat.IsDir() && !writeConfig {
-		file, err := os.Create(dir + "/netbox.conf")
+		f, err := os.Create(path.Join(dir, file))
 		if err != nil {
-			log.Fatalf("Failed to create netbox.conf: %v", err)
+			log.Fatalf("Failed to create %s: %v", file, err)
 		}
-		defer file.Close()
+		defer f.Close()
 		for _, ip := range ips {
-			fmt.Fprintf(file, "address=/%s/%s\n", ip.DNSName, ip.Address)
+			if outputFormat == "hosts" {
+				fmt.Fprintf(f, "%s\t%s\n", ip.Address, ip.DNSName)
+			} else {
+				fmt.Fprintf(f, "address=/%s/%s\n", ip.DNSName, ip.Address)
+			}
 		}
 	} else {
 		for _, ip := range ips {
+			if outputFormat == "hosts" {
+				fmt.Printf("%s\t%s\n", ip.Address, ip.DNSName)
+			} else {
 				fmt.Printf("address=/%s/%s\n", ip.DNSName, ip.Address)
 			}
 		}
 	}
-
-var apiBaseURL string
-
-func main() {
-	listenAddr := flag.String("listen", ":8080", "address and port to listen on (e.g. :8080 or 127.0.0.1:8080)")
-	flag.StringVar(&apiBaseURL, "api-url", "https://netbox.koszewscy.waw.pl/api", "NetBox API URL to fetch IP addresses")
-	dryRun := flag.Bool("dry-run", false, "if set, do not write to dnsmasq config file, just print the output")
-	flag.Parse()
-
-	if *dryRun {
-		log.Println("Dry run mode enabled, not writing to dnsmasq config file.")
-		CreateDnsMasqConfig(true)
-		return
-	}
-
-	http.HandleFunc("/update-dnsmasq", func(w http.ResponseWriter, r *http.Request) {
-		if r.Method != http.MethodGet {
-			w.WriteHeader(http.StatusMethodNotAllowed)
-			w.Write([]byte("Method not allowed"))
-			return
-		}
-		CreateDnsMasqConfig(false)
-		cmd := exec.Command("systemctl", "restart", "dnsmasq.service")
-		if err := cmd.Run(); err != nil {
-			log.Printf("Failed to restart dnsmasq.service: %v", err)
-			w.Write([]byte("\nWarning: Failed to restart dnsmasq.service.\n"))
-		}
-		w.Write([]byte("DNSMasq config updated."))
-	})
-	log.Printf("Starting web service on %s...", *listenAddr)
-	if err := http.ListenAndServe(*listenAddr, nil); err != nil {
-		log.Fatalf("Failed to start server: %v", err)
-	}
 }