# Stalwart Mail Server v0.16.11

Clean deployment of Stalwart mail server with username/password authentication only.

## Architecture

- **Version**: v0.16.11
- **Authentication**: Username/password only (NO OAuth/OIDC)
- **Configuration**: API-based (stored in RocksDB)
- **Storage**: Encrypted hcloud-volumes (20Gi)
- **Backup**: Daily restic backup to S3 at 3 AM
- **Web UI**: https://mail.basicstack.de

## Network Architecture

Stalwart uses a two-tier load balancing setup:

1. **Kubernetes LoadBalancer Services**: Four separate LoadBalancer services expose SMTP (25, 587, 465) and IMAP (143, 993) ports. The service type `LoadBalancer` is required because the Hetzner Cloud Controller Manager (CCM) automatically provisions and manages the Hetzner Load Balancer when it detects this service type.

2. **Hetzner Load Balancer**: Automatically managed by the Hetzner CCM. The load balancer distributes traffic across:
   - k3s-cp-1 (control plane node)
   - k3s-worker-1 through k3s-worker-5 (worker nodes)

### Traffic Flow

```
External Client → Hetzner Load Balancer → NodePort → K8s Service → Stalwart Pod
```

The Hetzner CCM watches for LoadBalancer-type services and automatically:
- Creates/updates the Hetzner LB configuration
- Configures health checks
- Maps service ports to node ports
- Manages target nodes

**Important**: Changing the service type from `LoadBalancer` to `NodePort` would break the automatic Hetzner LB management. The current setup is the correct configuration for our infrastructure.

## Files

- `stalwart-fresh-deployment.yaml` - Main deployment manifest
- `stalwart-admin-credentials-sealed.yaml` - Sealed secret for admin password
- `stalwart-s3-backup-sealed.yaml` - Sealed secret for S3 backup credentials

## Deployment

```bash
# Apply sealed secrets first
kubectl apply -f stalwart-admin-credentials-sealed.yaml
kubectl apply -f stalwart-s3-backup-sealed.yaml

# Create bootstrap config
kubectl create configmap stalwart-bootstrap-config \
  --from-literal=config.json='{"@type":"RocksDb","path":"/var/lib/stalwart"}' \
  -n stalwart

# Deploy Stalwart
kubectl apply -f stalwart-fresh-deployment.yaml
```

## Initial Admin Login

After deployment, log in at https://mail.basicstack.de with:
- Username: `admin`
- Password: (from stalwart-admin-credentials secret)

## Configuration

> **IMPORTANT:** The configuration is stored in the RocksDB and cannot be overwritten by a configuration file!

All configuration is done via the web UI or API. The bootstrap config only points to the RocksDB database location. NO config.toml files are used.

Check https://stalw.art/docs/ref/ for configuration possibilities.
The API access via /jmap seems to be too complex for the agent and the configruation has been done manually.

Refer to [manual configuration steps](manual_config_steps.md)

## Network Architecture

### Load Balancing Setup

Stalwart uses a two-tier load balancing architecture:

1. **Hetzner Cloud Load Balancer** (External Layer)
   - Provides the public-facing IP for mail services
   - Configured with k3s-cp-1 and all worker nodes as targets
   - Forwards traffic to Kubernetes NodePorts on the cluster nodes

2. **Kubernetes LoadBalancer Services** (Internal Layer)
   - Service type: LoadBalancer (managed by k3s ServiceLB)
   - Automatically configured by Hetzner CCM (Cloud Controller Manager)
   - Creates NodePorts that the Hetzner LB targets

### Traffic Flow

```
External Mail Client
    ↓
Hetzner Load Balancer (public IP)
    ↓
k3s Node NodePort (automatically assigned)
    ↓
Kubernetes LoadBalancer Service (stalwart-smtp / stalwart-imap)
    ↓
Stalwart Pod
```

### Why LoadBalancer Service Type is Required

The Kubernetes services MUST remain type `LoadBalancer` because:
- The Hetzner CCM automatically manages the Hetzner Load Balancer configuration
- When a service is type LoadBalancer, the CCM creates/updates the Hetzner LB targets
- Changing to NodePort would break this automatic management
- Manual Hetzner LB configuration would be required and error-prone

### Services

- `stalwart-smtp` (LoadBalancer): Ports 25, 587
- `stalwart-imap` (LoadBalancer): Port 993
- `stalwart-http` (ClusterIP): Port 8080 (web UI via Traefik Ingress)

## Ports

- SMTP: 25, 587
- IMAPS: 993 (secure only, port 143 disabled per DEV-359)
- HTTP: 8080 (web UI)

## Storage

Data is stored in `/var/lib/stalwart` using the RocksDB database format. This includes:
- Email messages
- User accounts
- Server configuration
- TLS certificates configuration

## Certificate Renewal

Refer to [Automatic Renewal TLS Certificate](CERTIFICATE-RENEWAL.md)