# DNS Automation

**Status:** Completed (2026-02-04)

**Goal:** Automatically generate DNS entries from host configurations

**Approach:** Leverage Nix to generate zone file entries from flake host configurations

Since most hosts use static IPs defined in their NixOS configurations, we can extract this information and automatically generate A records. This keeps DNS in sync with the actual host configs.

## Implementation

- [x] Add optional CNAME field to host configurations
  - [x] Added `homelab.dns.cnames` option in `modules/homelab/dns.nix`
  - [x] Added `homelab.dns.enable` to allow opting out (defaults to true)
  - [x] Documented in CLAUDE.md
- [x] Create Nix function to extract DNS records from all hosts
  - [x] Created `lib/dns-zone.nix` with extraction functions
  - [x] Parses each host's `networking.hostName` and `systemd.network.networks` IP configuration
  - [x] Collects CNAMEs from `homelab.dns.cnames`
  - [x] Filters out VPN interfaces (wg*, tun*, tap*, vti*)
  - [x] Generates complete zone file with A and CNAME records
- [x] Integrate auto-generated records into zone files
  - [x] External hosts separated to `services/ns/external-hosts.nix`
  - [x] Zone includes comments showing which records are auto-generated vs external
- [x] Update zone file serial number automatically
  - [x] Uses `self.sourceInfo.lastModified` (git commit timestamp)
- [x] Test zone file validity after generation
  - [x] NSD validates zone at build time via `nsd-checkzone`
- [x] Deploy process documented
  - [x] Merge to master, run auto-upgrade on ns1/ns2

## Files Created/Modified

| File | Purpose |
|------|---------|
| `modules/homelab/dns.nix` | Defines `homelab.dns.*` options |
| `modules/homelab/default.nix` | Module import hub |
| `lib/dns-zone.nix` | Zone generation functions |
| `services/ns/external-hosts.nix` | Non-flake host records |
| `services/ns/master-authorative.nix` | Uses generated zone |
| `services/ns/secondary-authorative.nix` | Uses generated zone |

## Usage

View generated zone:
```bash
nix eval .#nixosConfigurations.ns1.config.services.nsd.zones.'"home.2rjus.net"'.data --raw
```

Add CNAMEs to a host:
```nix
homelab.dns.cnames = [ "alias1" "alias2" ];
```

Exclude a host from DNS:
```nix
homelab.dns.enable = false;
```

Add non-flake hosts: Edit `services/ns/external-hosts.nix`