Add Nebula-Sync LXC container script

- Host script (ct/nebula-sync.sh) and install script for nebula-sync
- Prompts for primary/replica Pi-hole URL and API password, sync options, cron
- .env with PRIMARY/REPLICAS in url|password format, wrapper and systemd service
- Frontend JSON and header; notes on Pi-hole API and app_sudo requirement

Author: Gabriel Baker

ct/headers/nebula-sync

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+    _   __      _       _            _____                      
+   / | / /_  __(_)___  (_)___  ___  / ___/___  ______   _____   
+  /  |/ / / / / / __ \/ / __ \/ _ \ \__ \/ _ \/ ___/ | / / _ \  
+ / /|  / /_/ / / / / / / / / /  __/ ___/ /  __/ /   | |/ /  __/  
+/_/ |_/\__,_/_/_/ /_/_/_/ /_/\___/ /____/\___/_/    |___/\___/   
+                                                                  

ct/nebula-sync.sh

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+#!/usr/bin/env bash
+source <(curl -fsSL https://raw.githubusercontent.com/community-scripts/ProxmoxVED/main/misc/build.func)
+# Copyright (c) 2021-2026 community-scripts ORG
+# Author: gabriel403
+# License: MIT | https://github.com/community-scripts/ProxmoxVE/raw/main/LICENSE
+# Source: https://github.com/lovelaze/nebula-sync
+
+APP="Nebula-Sync"
+var_tags="${var_tags:-dns;sync}"
+var_cpu="${var_cpu:-1}"
+var_ram="${var_ram:-512}"
+var_disk="${var_disk:-2}"
+var_os="${var_os:-debian}"
+var_version="${var_version:-13}"
+var_unprivileged="${var_unprivileged:-1}"
+
+header_info "$APP"
+variables
+color
+catch_errors
+
+function update_script() {
+  header_info
+  check_container_storage
+  check_container_resources
+  if [[ ! -f /opt/nebula-sync/nebula-sync ]]; then
+    msg_error "No ${APP} Installation Found!"
+    exit
+  fi
+  RELEASE=$(curl -fsSL https://api.github.com/repos/lovelaze/nebula-sync/releases/latest | sed -n 's/.*"tag_name": *"\([^"]*\)".*/\1/p')
+  if [[ ! -f /opt/nebula-sync_version.txt ]] || [[ "${RELEASE}" != "$(cat /opt/nebula-sync_version.txt)" ]]; then
+    msg_info "Updating Nebula-Sync to v${RELEASE}"
+    if [[ -f /usr/local/bin/update_nebula-sync ]]; then
+      /usr/local/bin/update_nebula-sync
+    else
+      msg_error "Update script not found!"
+      exit
+    fi
+    msg_ok "Updated Nebula-Sync"
+  else
+    msg_ok "No update required. Nebula-Sync is already at v${RELEASE}."
+  fi
+  msg_ok "Updated successfully!"
+  exit
+}
+
+start
+build_container
+description
+
+msg_ok "Completed successfully!\n"
+echo -e "${CREATING}${GN}${APP} setup has been successfully initialized!${CL}"
+echo -e "${INFO}${YW} Nebula-Sync runs as a service and will sync your Pi-hole instances.${CL}"
+echo -e "${INFO}${YW} Configuration:${CL}"
+echo -e "${TAB}${GATEWAY}${BGN}/opt/nebula-sync/.env${CL}"
+echo -e "${INFO}${YW} View logs:${CL}"
+echo -e "${TAB}${GATEWAY}${BGN}journalctl -u nebula-sync -f${CL}"

frontend/public/json/nebula-sync.json

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+{
+    "name": "Nebula-Sync",
+    "slug": "nebula-sync",
+    "categories": [
+        5
+    ],
+    "date_created": "2025-01-27",
+    "type": "ct",
+    "updateable": true,
+    "privileged": false,
+    "interface_port": null,
+    "documentation": "https://github.com/lovelaze/nebula-sync",
+    "website": "https://github.com/lovelaze/nebula-sync",
+    "logo": "https://cdn.jsdelivr.net/gh/selfhst/icons@main/webp/pi-hole.webp",
+    "config_path": "/opt/nebula-sync/.env",
+    "description": "Nebula-Sync is a tool that synchronizes configuration of multiple Pi-hole v6.x instances. It allows you to keep multiple Pi-hole instances in sync by replicating settings, blocklists, whitelists, custom DNS entries, and other configurations from a primary instance to one or more replica instances. This is particularly useful for maintaining consistency across multiple Pi-hole servers in a network or ensuring redundancy with synchronized configurations.",
+    "install_methods": [
+        {
+            "type": "default",
+            "script": "ct/nebula-sync.sh",
+            "resources": {
+                "cpu": 1,
+                "ram": 512,
+                "hdd": 2,
+                "os": "debian",
+                "version": "13"
+            }
+        }
+    ],
+    "default_credentials": {
+        "username": null,
+        "password": null
+    },
+    "notes": [
+        {
+            "text": "Requires Pi-hole v6.x instances with API access enabled",
+            "type": "info"
+        },
+        {
+            "text": "You will be prompted for primary and replica Pi-hole IP addresses and API passwords during installation",
+            "type": "info"
+        },
+        {
+            "text": "IMPORTANT: Pi-hole API must have sudo permissions enabled. Set 'app_sudo = true' in /etc/pihole/pihole.toml under [webserver.api] section on all Pi-hole instances, then restart pihole-FTL service",
+            "type": "warning"
+        },
+        {
+            "text": "The API password is the Pi-hole web interface password (not an API token). Ensure API access is enabled in Pi-hole Settings → API/Web interface",
+            "type": "info"
+        },
+        {
+            "text": "By default, all settings are synchronized. You can choose custom sync options during setup",
+            "type": "info"
+        },
+        {
+            "text": "Update with: update_nebula-sync",
+            "type": "info"
+        },
+        {
+            "text": "Configuration file: /opt/nebula-sync/.env",
+            "type": "info"
+        }
+    ]
+}