# Hostinger DNS Sync

A lightweight Docker container that watches **Traefik router labels** on your Docker host and automatically creates/updates **Hostinger DNS records** to point your subdomains at your server's public IP.

## How it works

```
Docker event (container start/stop)
        │
        ▼
  Scan all containers for Traefik labels
  e.g. traefik.http.routers.myapp.rule=Host(`app.example.com`)
        │
        ▼
  Extract hostnames → filter by your DOMAIN
        │
        ▼
  Call Hostinger DNS API → upsert A records
```

On startup it does a full sync, then it listens to Docker events in real-time and re-syncs whenever a container starts or stops.

---

## Prerequisites

- Docker + Docker Compose
- A domain on Hostinger with API access enabled
- Your server's public IP reachable from the internet

---

## Setup

### 1. Get your Hostinger API key

1. Log in to [hPanel](https://hpanel.hostinger.com)
2. Go to **Profile → API Tokens**
3. Create a new token with DNS read/write permissions

### 2. Clone & configure

```bash
git clone <this-repo>
cd hostinger-dns-sync
cp .env.example .env
nano .env   # fill in HOSTINGER_API_KEY and DOMAIN
```

### 3. Deploy

```bash
docker compose up -d
```

Check logs:
```bash
docker compose logs -f hostinger-dns-sync
```

---

## Environment variables

| Variable | Required | Default | Description |
|---|---|---|---|
| `HOSTINGER_API_KEY` | ✅ | — | API token from hPanel |
| `DOMAIN` | ✅ | — | Root domain, e.g. `example.com` |
| `PUBLIC_IP` | ❌ | auto-detected | Override server IP |
| `RECORD_TYPE` | ❌ | `A` | `A` (IPv4) or `AAAA` (IPv6) |
| `TTL` | ❌ | `3600` | DNS TTL in seconds |
| `DELETE_ORPHANS` | ❌ | `false` | Delete DNS records no longer in Traefik |
| `DRY_RUN` | ❌ | `false` | Preview changes without applying |

---

## Traefik label format

The service reads **all** containers with a label matching:

```
traefik.http.routers.<name>.rule=Host(`subdomain.example.com`)
```

Multi-host rules are supported:

```
traefik.http.routers.<name>.rule=Host(`a.example.com`) || Host(`b.example.com`)
```

---

## Orphan cleanup

By default, the service only **adds/updates** records and never deletes them.
Set `DELETE_ORPHANS=true` to automatically remove DNS records for subdomains
that are no longer referenced by any Traefik router.

⚠️  Use with care if you manage other records manually on the same domain.

---

## Test without making changes

```bash
DRY_RUN=true docker compose up hostinger-dns-sync
```

---

## Security notes

- The Docker socket is mounted **read-only** (`:ro`) — the container cannot start/stop containers.
- The API key is passed via environment variable, never baked into the image.
- Add `.env` to your `.gitignore`.