Initial commit.

.gitignore

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+.vscode
+build

go.mod

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+module netbox-dns-updater

netbox-dns-updater.go

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+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+type IPAddress struct {
+	Address string `json:"address"`
+	DNSName string `json:"dns_name"`
+}
+
+type NetBoxResponse struct {
+	Results []IPAddress `json:"results"`
+}
+
+func FetchNetboxIPAddresses(apiURL, token string) ([]IPAddress, error) {
+	req, err := http.NewRequest("GET", apiURL, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Accept", "application/json; indent=2")
+	req.Header.Set("Authorization", "Token "+token)
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(resp.Body)
+		return nil, fmt.Errorf("unexpected status: %s, body: %s", resp.Status, string(body))
+	}
+
+	var nbResp NetBoxResponse
+	decoder := json.NewDecoder(resp.Body)
+	if err := decoder.Decode(&nbResp); err != nil {
+		return nil, err
+	}
+
+	// Filter out entries with empty DNSName and strip CIDR from Address
+	var filtered []IPAddress
+	for _, ip := range nbResp.Results {
+		if ip.DNSName != "" {
+			ip.Address = strings.Split(ip.Address, "/")[0]
+			filtered = append(filtered, ip)
+		}
+	}
+	return filtered, nil
+}
+
+func CreateDnsMasqConfig() {
+	token := os.Getenv("NETBOX_TOKEN")
+	if token == "" {
+		home := os.Getenv("HOME")
+		paths := []string{
+			home + "/.netbox/token",
+			"/etc/netbox/token",
+		}
+		for _, path := range paths {
+			data, err := os.ReadFile(path)
+			if err == nil {
+				token = strings.TrimSpace(string(data))
+				break
+			}
+		}
+		if token == "" {
+			log.Fatal("NETBOX_TOKEN not set and no token file found")
+		}
+	}
+	apiURL := "https://netbox.koszewscy.waw.pl/api/ipam/ip-addresses/"
+	ips, err := FetchNetboxIPAddresses(apiURL, token)
+	if err != nil {
+		log.Fatalf("Error fetching IP addresses: %v", err)
+	}
+
+	dir := "/etc/dnsmasq.d"
+	if stat, err := os.Stat(dir); err == nil && stat.IsDir() {
+		file, err := os.Create(dir + "/netbox.conf")
+		if err != nil {
+			log.Fatalf("Failed to create netbox.conf: %v", err)
+		}
+		defer file.Close()
+		for _, ip := range ips {
+			fmt.Fprintf(file, "address=/%s/%s\n", ip.DNSName, ip.Address)
+		}
+	} else {
+		for _, ip := range ips {
+			fmt.Printf("address=/%s/%s\n", ip.DNSName, ip.Address)
+		}
+	}
+}
+
+func main() {
+	listenAddr := flag.String("listen", ":8080", "address and port to listen on (e.g. :8080 or 127.0.0.1:8080)")
+	flag.Parse()
+
+	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()
+		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)
+	}
+}

netbox-dns-updater.service

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+[Unit]
+Description=NetBox DNSMasq Updater Web Service
+After=network.target
+
+[Service]
+Type=simple
+ExecStart=/usr/local/bin/netbox-dns-updater -listen=:8080
+Restart=on-failure
+User=nobody
+Group=nogroup
+
+[Install]
+WantedBy=multi-user.target

query-netbox.sh

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+#!/bin/bash
+
+. /root/.netbox-token
+
+# Build DNS data file from NetBox
+curl -s \
+  -H "Accept: application/json; indent=2" \
+  -H "Authorization: Token $NETBOX_TOKEN" \
+  "https://netbox.koszewscy.waw.pl/api/ipam/ip-addresses/" | \
+  jq -r '.results[] | select(.dns_name!="") | [(.address | split("/"))[0], .dns_name] | @tsv' | \
+  while read ip name
+  do
+    echo "address=/$name/$ip"
+  done > /etc/dnsmasq.d/netbox.conf
+
+# Restart the DNSMasq service
+systemctl restart dnsmasq.service