# CoreDNS NetBox Sync

This container automates the generation of DNS zone files for CoreDNS (or BIND) by synchronizing data from [NetBox](https://github.com/netbox-community/netbox). It fetches IPAM data (active IPs with DNS names) and DNS Plugin records.

## Features

*   **Automated Synchronization:** Periodically fetches data from NetBox (Default: 10 minutes).
*   **Fail-Safe Operation:** If NetBox is unreachable or returns errors, the existing zone files are preserved to prevent `NXDOMAIN` issues.
*   **Dual Zone Support:** Generates both Forward and Reverse (PTR) zones.
*   **Intelligent Fallback:** Automatically configures a fallback Nameserver if no NS records are defined in NetBox.

## Configuration

Configuration is handled entirely via environment variables.

### Required Variables

| Variable | Description |
| :--- | :--- |
| `NETBOX_URL` | The full URL to the NetBox instance (e.g., `http://netbox.local`). |
| `NETBOX_TOKEN` | The API Token for authentication (Read-Only permissions are sufficient). |

### Optional Variables

| Variable | Default | Description |
| :--- | :--- | :--- |
| `REFRESH_INTERVAL` | `600` | Synchronization interval in seconds. |
| `ZONE_NAME` | `klenzel.net` | The DNS zone name to manage. |
| `REVERSE_ZONE_NAME` | `172.in-addr.arpa` | The reverse lookup zone name. |
| `OUTPUT_FILE_FWD` | `/zones/db.klenzel.net` | Path inside the container for the forward zone file. |
| `OUTPUT_FILE_REV` | `/zones/db.reverse.arpa` | Path inside the container for the reverse zone file. |
| `FALLBACK_NS_HOSTNAME`| `fks-01-cl-cdns` | Hostname used for NS record if none exist in NetBox. |
| `FALLBACK_NS_IP` | `172.25.16.152` | IP address for the fallback NS glue record. |

## Usage

### Docker

1.  **Build the image:**
    ```bash
    docker build -t local/dns-sync .
    ```

2.  **Run with environment variables:**
    ```bash
    docker run -d \
      --name klzDNS-worker \
      --restart unless-stopped \
      --net=container:klzDNS-coredns \
      -v klzDNS-data:/zones \
      -e NETBOX_URL="http://172.30.242.99" \
      -e NETBOX_TOKEN="your-secret-token" \
      local/dns-sync
    ```

### Using a `.env` file

1.  Create a `.env` file based on the example:
    ```bash
    cp .env.example .env
    # Edit .env and add your credentials
    ```

2.  Run the container referencing the file:
    ```bash
    docker run -d \
      --name klzDNS-worker \
      --restart unless-stopped \
      --net=container:klzDNS-coredns \
      -v klzDNS-data:/zones \
      --env-file .env \
      local/dns-sync
    ```