homelab/README.md

# homelab

Flake-based NixOS config. Hosts: `jupiter` (ZimaBlade, NAS + services),
`neptun` (netcup VPS: public reverse proxy, Authentik, headscale),
`mercury` (Raspberry Pi 3B+, DNS/DHCP), `terra` (desktop).

## Structure

```
flake.nix                  # inputs + nixosConfigurations (jupiter, neptun, kexec, ...)
common.nix                 # shared base: user, ssh, nix, firewall, timezone
services/                  # one reusable module per service, by category
  media/     jellyfin, audiobookshelf, the *arrs, sabnzbd, seerr, ...
  network/   caddy, samba, avahi, pihole, unbound
  vpn/       tailscale, headscale (control server), headplane (its web UI)
  identity/  authentik (OIDC provider, from the authentik-nix flake)
  dev/       gitea
  desktop/   hyprland
  containers.nix           # podman backend, shared across categories
hosts/
  jupiter/                 # ZimaBlade NAS
    configuration.nix      #   host bits + imports common + the services it runs
    disk-config.nix        #   disko: eMMC partitions
    hardware-configuration.nix
    secrets.nix            #   sops-nix wiring
    vm.nix                 #   VirtualBox test image (jupiter-vbox)
  neptun/                     # netcup public reverse proxy + tailnet node
    configuration.nix  disk-config.nix  hardware-configuration.nix  secrets.nix
secrets/                   # age-encrypted sops files, one per host
scripts/                   # deploy, edit_secrets
```

Hosts compose by importing `common.nix` + whichever `services/*` modules they
run. Each service module opens its own firewall ports.

## Test in VirtualBox (no hardware needed)

```
nix build .#nixosConfigurations.jupiter-vbox.config.system.build.virtualBoxOVA
VBoxManage import result/*.ova --vsys 0 --vmname jupiter-vbox
VBoxManage startvm jupiter-vbox --type headless
```
Login `darman` / `test`. Forward ports with `VBoxManage modifyvm ... --natpf1`.

## First install on the ZimaBlade — nixos-anywhere + disko

Wipes the OS disk and installs the flake over SSH. No USB needed if the box
already runs Linux (ZimaOS) reachable by root SSH — nixos-anywhere kexecs into
an installer, partitions via disko, installs.

> ⚠️  The OS disk in `disk-config.nix` is WIPED. Set `device` to the OS disk
> ONLY (by-id). Back up / physically identify the NAS data disk first — it must
> NOT appear in disko. `lsblk -o NAME,SERIAL,SIZE,MODEL` to identify.

1. Set the real OS disk id in `hosts/jupiter/disk-config.nix`
   (`ls -l /dev/disk/by-id`), and the data-disk mount in `configuration.nix`.
2. Add your login SSH pubkey to `users.users.darman.openssh.authorizedKeys.keys`.
3. Set the real samba password:
   ```
   export SOPS_AGE_KEY_FILE=~/.config/sops/age/keys.txt
   nix shell nixpkgs#sops -c sops secrets/jupiter.yaml   # edit, commit
   ```
4. Stage the pre-generated host key so sops can decrypt on boot #1
   (private key lives off-repo in `~/.config/homelab/jupiter/`):
   ```
   install -Dm600 ~/.config/homelab/jupiter/ssh_host_ed25519_key \
     /tmp/extra/etc/ssh/ssh_host_ed25519_key
   install -Dm644 ~/.config/homelab/jupiter/ssh_host_ed25519_key.pub \
     /tmp/extra/etc/ssh/ssh_host_ed25519_key.pub
   ```
5. Run from your laptop:
   ```
   nix run github:nix-community/nixos-anywhere -- \
     --flake .#jupiter \
     --extra-files /tmp/extra \
     --generate-hardware-config nixos-generate-config ./hosts/jupiter/hardware-configuration.nix \
     --target-host root@<zimablade-ip>
   ```
   `--extra-files` plants the host key before first boot (its age identity is
   already a recipient in `.sops.yaml`, so `/run/secrets/samba_password`
   decrypts on boot #1). `--generate-hardware-config` pulls the target's real
   kernel modules into the placeholder. Commit the result. Reboot into NixOS.

Manual alternative (USB ISO): boot installer, `disko` the disk, then
`nixos-install --flake .#jupiter`.

## Deploy (the `./deploy` wrapper)

All arguments mandatory — no default host, no default config.

```
./deploy kexec   <host>            # headless kexec into a RAM installer (RO-root box)
./deploy install <config> <host>   # first install; wipes OS disk, ships host key
./deploy switch  <config> <host>   # rebuild + activate on a running host
./deploy boot|test <config> <host> # stage for next boot / activate without boot entry
./deploy image   <config>          # build an SD-card image (mercury)
./deploy flash   <config> <dev>    # build SD image, write it, drop the sops age key
```
`switch`/`boot`/`test` prompt for darman's password (`wheelNeedsPassword`).
`<config>` is a `nixosConfigurations` name (`jupiter`, `neptun`). Its pre-generated
SSH host key lives at `~/.config/homelab/<config>/ssh_host_ed25519_key`.

Examples:
```
./deploy switch jupiter jupiter.sol
./deploy install neptun 159.195.64.117
```
Rollback: `nixos-rebuild switch --rollback` on the host, or pick a prior
generation at boot.

## Post-deploy steps (per host)

Things the flake cannot do for you. Skipping these leaves a host that builds
and boots but doesn't work.

### Every host, immediately after a first install

```
ssh darman@<host> sudo -v          # DO NOT SKIP
```

`users.mutableUsers` is `true`, so `/etc/shadow` is written **once**, when the
user is created. If the sops secret wasn't readable at that moment the account
gets `!` (locked) permanently — `deploy switch` will never fix it, because the
activation script only sets a password for users not already in `/etc/shadow`.
Combined with `wheelNeedsPassword = true` and `PermitRootLogin = "no"` that
means no way to escalate, and recovery is physical: netcup's rescue system for
neptun, or pulling the SD card for mercury. Verify sudo while you still have
another way in.

### neptun (netcup VPS)

1. **Edge firewall.** In netcup's panel, inbound `ACCEPT` for TCP 22/80/443/2222
   **and a rule accepting inbound UDP**. The firewall is stateless: without the
   UDP rule every DNS and NTP *reply* is dropped, and nothing on the box reports
   an error — it looks like headscale crash-looping on its DERP fetch and Caddy
   failing ACME. `grep -A1 '^Udp:' /proc/net/snmp` showing `InDatagrams 0` is the
   tell. Rules apply on VM restart, not on save. This is safe: `nixos-fw` is
   stateful and default-deny, so it remains the real policy.
   Also open UDP 3478 (STUN) and 41641 (tailscale direct).
2. **Authentik** creates `akadmin` on first start; log in at
   `https://auth.mgaction.town` with `authentik_bootstrap_password` from sops.
   The username is hardcoded upstream and the bootstrap runs once — later
   changes to the env vars are ignored.
3. **Bootstrap the tailnet** (headscale starts with an empty database):
   ```
   sudo headscale users create darman
   sudo headscale preauthkeys create --user darman --reusable --expiration 24h
   ```
   Put that key in **every** host's sops file as `tailscale_authkey` and rebuild.
4. **Headplane API key** — defaults to 90d, after which headplane silently stops
   listing nodes:
   ```
   sudo headscale apikeys create --expiration 999d      # -> headplane_headscale_api_key
   ```
5. **Headplane OIDC.** In Authentik create an OAuth2/OpenID provider
   (confidential, redirect `https://vpn.mgaction.town/admin/oidc/callback`,
   **a signing key must be selected** or discovery exposes no JWKS) and an
   application with slug **`headplane`** — the slug is what makes the issuer
   `.../application/o/headplane/` in `services/vpn/headplane.nix`. Client ID goes
   in that file, client secret into sops.
6. **Pin jupiter's tailnet address.** `networking.hosts` in
   `hosts/neptun/configuration.nix` carries jupiter's IP, because neptun runs
   `--accept-dns=false` and cannot use MagicDNS. Until it matches
   `headscale nodes list`, the `abs.` and `git.` vhosts fail to proxy.

### jupiter

- `chown -R gitea:gitea /mnt/data/AppData/gitea` after the first deploy (the
  repos were copied in over CIFS as `darman:users`).
- **Re-enrolling after the headscale database was recreated:** `tailscaled`
  keeps its old node key and reports `Running`, and the autoconnect unit exits
  early on that state without ever sending the new pre-auth key. Force it:
  ```
  sudo tailscale logout && sudo systemctl restart tailscaled-autoconnect
  ```

### mercury (Raspberry Pi 3B+)

- `./deploy flash mercury /dev/sdX` writes the dedicated age key to the root
  partition. Without `~/.config/homelab/mercury/age.txt` it silently skips that
  step and **no secret decrypts on the box** — check `ls /run/secrets` after
  first boot.
- It boots from an SD card, so config changes are `./deploy switch mercury <ip>`
  (an aarch64 build — needs `extra-platforms` + binfmt on the laptop, see the
  gotchas in `CLAUDE.md`) rather than a reflash.
- **Suspect the card first** when binaries crash with `Illegal instruction` or
  services fail inexplicably. Failing flash returns corrupt data with no I/O
  errors in `dmesg`:
  ```
  sudo nix-store --verify --check-contents      # add --repair to fix
  ```
  A card that has corrupted one path will corrupt more. Replace it and reflash;
  only pihole's runtime state (query history, dynamic leases) is lost — the
  static leases are declarative.

## Adding a service

Copy the `whoami` block in `oci-containers.containers`, swap image/ports/volumes.
Native NixOS module exists for many apps (Nextcloud, Jellyfin, Grafana...) —
prefer `services.<app>` over a container when available. Add a `caddy`
`virtualHosts` block to expose it.

## Notes

- Backend is Podman with `dockerCompat` — `docker` CLI works, no daemon.
- Samba keeps its own password DB. `services.samba` never sets it; a systemd
  oneshot (`samba-smbpasswd`) provisions it. Host reads the password from
  `/run/secrets/samba_password` (**sops-nix**); the VM falls back to plaintext
  `/etc/samba/smb-password`.
- Secrets: `secrets/jupiter.yaml` is age-encrypted (safe to commit) to two
  recipients in `.sops.yaml` — the **admin** key (edit on laptop,
  `~/.config/sops/age/keys.txt`) and the **jupiter host** key (derived from its
  SSH host key via `ssh-to-age`, decrypts at runtime). Private keys live
  off-repo and are gitignored. Rotate/add recipients with `sops updatekeys`.
- Data disk: plain `fileSystems."/mnt/data"` in configuration.nix — kept out of
  disko so it is never formatted. Reference by `by-id` / `by-uuid`.
- `system.stateVersion` = `26.05`, install-time schema. Do NOT bump on upgrades.
- Terraform is not used: a single bare-metal box has no provider API. disko +
  nixos-anywhere cover provisioning natively.