# Architecture Decisions & Patterns

> **Purpose**: Record of important decisions, patterns, and "why we do it this way"
> **Update Frequency**: When making significant architectural choices

## Service Organization

### Authentication Strategy

**Decision**: Services use their own built-in authentication, not Authelia
**Reason**: Most *arr services and media tools have robust auth systems
**Exception**: Consider Authelia for future services that lack authentication

### LXC vs Docker

**Keep in Docker**:
- NZBGet (requires specific volume mapping, works well in Docker)
- Multi-container stacks
- Services requiring Docker-specific features

**Migrate to LXC**:
- Single-purpose services (Sonarr, Radarr, etc.)
- Services benefiting from isolation
- Stateless applications

## File Permissions

### Media Files

**Standard**: All media files and folders must be 777
**Reason**:
- NFS mounts between multiple systems with different UID mappings
- Jellyfin runs in LXC with UID namespace mapping (100107)
- Sonarr runs in LXC with different UID mapping
- NZBGet runs in Docker with UID 1000

**Implementation**:
- NZBGet: `UMask=0000` to create files with 777
- Sonarr: Media management → Set permissions → chmod 777
- Manual fixes: `chmod -R 777` on media directories as needed

## Network Architecture

### Network Isolation Strategy

**Goal**: Isolate IoT (KavCorp-IOT) and Guest (KavCorp-Guest) WiFi networks from the main LAN, while allowing Smart Home VMs to access IoT devices.

#### Constraint: Unmanaged Gigabyte Switches

The Gigabyte 10G switches provide 10G backhaul and 2.5G PoE to UniFi APs, but they are **unmanaged** and don't support VLAN tagging. This means VLAN tags from UniFi APs are stripped when traffic passes through.

**Workaround**: DHCP-based isolation (L3 firewall rules instead of L2 VLANs)

#### IP Subnet Scheme

| Subnet | Range | Purpose | DHCP Source |
|--------|-------|---------|-------------|
| Main LAN | 10.4.2.0/24 | Trusted devices, Proxmox hosts, services | OPNsense |
| IoT | 10.4.10.0/24 | KavCorp-IOT SSID devices | OPNsense or UniFi |
| Guest | 10.4.20.0/24 | KavCorp-Guest SSID devices | OPNsense or UniFi |

#### OPNsense Firewall Rules (Planned)

| Source | Destination | Action | Notes |
|--------|-------------|--------|-------|
| 10.4.10.0/24 (IoT) | 10.4.2.0/24 (LAN) | **Block** | Isolate IoT from LAN |
| 10.4.20.0/24 (Guest) | 10.4.2.0/24 (LAN) | **Block** | Isolate Guest from LAN |
| 10.4.20.0/24 (Guest) | 10.4.10.0/24 (IoT) | **Block** | Isolate Guest from IoT |
| Smart Home VMs | 10.4.10.0/24 (IoT) | **Allow** | Home Assistant → IoT devices |
| 10.4.10.0/24 (IoT) | Internet | **Allow** | IoT internet access |
| 10.4.20.0/24 (Guest) | Internet | **Allow** | Guest internet access |

#### Limitations of DHCP Workaround

- **Not true L2 isolation**: All traffic on same broadcast domain
- **IP spoofing possible**: Malicious device could use LAN IP range
- **Sufficient for**: IoT devices and guests (low threat actors)
- **Future upgrade**: Replace Gigabyte switches with managed 2.5G PoE switches for proper VLANs

#### VLAN IDs (For Future Reference)

| VLAN | Name | Subnet | Purpose |
|------|------|--------|---------|
| 1 | Default | 10.4.2.0/24 | Management, trusted PCs, Proxmox hosts |
| 10 | IoT | 10.4.10.0/24 | IoT devices, cameras, smart home |
| 20 | Guest | 10.4.20.0/24 | Guest WiFi, isolated |

### Router/Firewall

**Decision**: OPNsense VM 130 on pm4 (server closet)
**Status**: Deployed, pending WAN cutover

**Reason**:
- Free, full-featured firewall/router
- Inter-subnet firewall rules for IoT/Guest isolation
- IDS/IPS capability
- pm4 is in server closet next to AT&T modem (avoids routing WAN over backhaul)

**Network Interfaces (VM 130)**:
| Interface | Bridge | Purpose | Status |
|-----------|--------|---------|--------|
| net0 | vmbr0 | LAN (10.4.2.0/24) | Configured |
| net1 | vmbr1 | WAN (to AT&T modem) | Configured |

**pm4 Bridge Configuration**:
| Bridge | Physical NIC | Purpose |
|--------|--------------|---------|
| vmbr0 | eno1 (Intel I226-V) | LAN - all VMs/LXCs |
| vmbr1 | enx6c1ff76e4d47 (USB 2.5G) | WAN - OPNsense only |

**HA/Failover Consideration**:
- Current: Single OPNsense on pm4 (SPOF)
- Future options:
  1. OPNsense HA with CARP (requires second USB NIC on another node)
  2. Keep current router as cold standby (swap cables if pm4 fails)

**Alternative Considered**: Ubiquiti Dream Machine
- Rejected due to cost and ecosystem lock-in
- OPNsense more flexible for homelab

**Alternative Considered**: OPNsense on Elantris (basement)
- Rejected because WAN would need to traverse 10G backhaul
- Would require managed switches for WAN VLAN isolation

### 10G Backhaul (Planned)

**Decision**: 10G RJ45 between server closet and basement
**Hardware**: 2× GiGaPlus 6-Port 10G PoE switches ($101 each)
**Why GiGaPlus over UniFi**:
- Native 10G RJ45 (no SFP+ transceivers needed)
- Includes PoE for APs
- $202 total vs $800+ for UniFi equivalent
- Cat6 can handle 10G at house distances (<55m)

### WiFi (Planned)

**Decision**: UniFi APs with mixed models
**Hardware**:
- 1× U6 Enterprise (existing) - server closet/upstairs
- 2× U7 Pro ($189 each) - basement + main floor

**Why UniFi**:
- Multiple SSIDs mapped to VLANs
- Seamless roaming between APs
- Centralized management via controller
- Better than Asus mesh for VLAN support

**Controller**: LXC on Proxmox (free) via community helper script

### Reverse Proxy

**Decision**: Single Traefik instance handles all external access
**Location**: LXC 104 on pm2
**Benefits**:
- Single point for SSL/TLS management
- Automatic Let's Encrypt certificate renewal
- Centralized routing configuration
- DNS-01 challenge for wildcard certificates

### Service Domains

**Pattern**: `<service>.kavcorp.com`
**DNS**: All subdomains point to public IP (99.74.188.161)
**Routing**: Traefik inspects Host header and routes internally

## Storage Architecture

### Media Storage

**Decision**: NFS mount from elantris for all media
**Path**: `/mnt/pve/elantris-media` → elantris `/el-pool/media`
**Reason**:
- Centralized storage
- Accessible from all cluster nodes
- Large capacity (24TB ZFS pool)
- Easy to backup/snapshot

### LXC Root Filesystems

**Decision**: Store on KavNas NFS for most services
**Reason**:
- Easy backups
- Portable between nodes
- Network storage sufficient for most workloads

**Exception**: High I/O services use local-lvm

## Monitoring & Maintenance

### Configuration Management

**Decision**: Manual configuration with documentation
**Reason**: Small scale doesn't justify Ansible/Terraform complexity
**Trade-off**: Requires disciplined documentation updates

### Backup Strategy

**Decision**: Proxmox built-in backup to KavNas
**Frequency**: [To be determined]
**Retention**: [To be determined]

## Common Patterns

### Adding a New Service Behind Traefik

1. Deploy service with static IP in 10.4.2.0/24 range
2. Create Traefik config in `/etc/traefik/conf.d/<service>.yaml`
3. Use pattern:
   ```yaml
   http:
     routers:
       <service>:
         rule: "Host(`<service>.kavcorp.com`)"
         entryPoints: [websecure]
         service: <service>
         tls:
           certResolver: letsencrypt
     services:
       <service>:
         loadBalancer:
           servers:
             - url: "http://<ip>:<port>"
   ```
4. Traefik auto-reloads (no restart needed)
5. Update `docs/INFRASTRUCTURE.md` with service details

### Troubleshooting Permission Issues

1. Check file ownership: `ls -la /path/to/file`
2. Check if 777: `stat /path/to/file`
3. Fix permissions: `chmod -R 777 /path/to/directory`
4. For NZBGet: Verify `UMask=0000` in nzbget.conf
5. For Sonarr/Radarr: Check Settings → Media Management → Set Permissions

### Node SSH Access

**From local machine**:
- User: `kavren`
- Key: `~/.ssh/id_ed25519`

**Between cluster nodes**:
- User: `root`
- Each node has other nodes' keys in `/root/.ssh/authorized_keys`
- Proxmox web UI uses node SSH for shell access

## Known Issues & Workarounds

### Jellyfin Not Seeing Media After Import

**Symptom**: Files imported to `/media/tv` but Jellyfin shows empty
**Cause**: Jellyfin LXC mount not active or permissions wrong
**Fix**:
1. Restart Jellyfin LXC: `pct stop 121 && pct start 121`
2. Verify mount inside LXC: `pct exec 121 -- ls -la /media/tv/`
3. Fix permissions if needed: `chmod -R 777 /mnt/pve/elantris-media/tv/`

### Sonarr/Radarr Import Failures

**Symptom**: "Access denied" errors in logs
**Cause**: Permission mismatch between download client and *arr service
**Fix**: Ensure download folder has 777 permissions

## Future Considerations

- [ ] Automated backup strategy
- [ ] Monitoring/alerting system (Prometheus + Grafana?)
- [ ] Consider Authelia for future services without built-in auth
- [ ] Document disaster recovery procedures
- [ ] Consider consolidating Docker hosts