darmanandClaude Opus 4.8
c87fd3b1f2
`install <config> localhost` assumed systemd-boot. terra's CachyOS boots
Limine, so it stopped at "/boot/loader/entries doesn't exist" — the check
added in e538788 doing its job, but with nowhere to go.
Limine cannot help here at all: `bootctl status` lists it as
`✗ One-shot entry control`, and CachyOS's pacman hooks regenerate
limine.conf regardless. So drop below the bootloader entirely and use the
firmware's own BootNext, pointing at a temporary UEFI entry that
EFI-stub-boots the installer kernel straight off the ESP. That keeps the
property which makes this safe to attempt: BootNext is spent by that one
boot, so a failed try still comes back on the normal bootloader.
- picked at runtime: systemd-boot loader entry when $BOOT/loader/entries
exists, else arm_efi_bootnext(). jupiter/neptun and terra-after-install
keep the systemd-boot path.
- `efibootmgr --create-only`, NOT `--create`: the latter pushes the entry
to the front of BootOrder, which would make a wiped installer the
permanent default if the install died halfway.
- the EFI stub loads initrd= from the volume it was loaded from, so this
mode stages on --print-esp-path rather than --print-boot-path.
- stale entries from an earlier attempt are removed before adding one, and
homelab-auto-install.service deletes the entry as soon as it boots, so
nothing lingers in NVRAM pointing at a reformatted partition.
- label matching is EXACT ("Homelab Installer"); a prefix match would have
deleted this box's Windows or Limine entry.
Verified against terra's real NVRAM (read-only): the label parser picks out
Limine/UEFI OS/Windows by exact name and rejects prefixes, and both branches
run end-to-end under stubs — BootNext mode emits the right --disk/--part,
loader path and initrd= cmdline, systemd-boot mode still writes its entry and
never calls efibootmgr.
README/CLAUDE.md corrected: terra runs Limine, not systemd-boot.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
195 lines
13 KiB
Markdown
195 lines
13 KiB
Markdown
# CLAUDE.md
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This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
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Flake-based NixOS config for a homelab. Hosts: **jupiter** (ZimaBlade NAS, x86_64),
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**neptun** (netcup public reverse proxy + tailnet node, x86_64), **mercury** (Raspberry
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Pi 3B+ DNS/DHCP, aarch64). See `README.md` for the full install/deploy walkthrough.
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## Layout
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```
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flake.nix # nixosConfigurations: real hosts + test/util targets
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common.nix # shared base: user darman (key-only ssh), nix settings, firewall :22, tz
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services/<cat>/*.nix # one reusable NixOS module per service, grouped by category
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# (media, network, vpn, identity, dev, desktop); each opens
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# ITS OWN firewall ports. services/containers.nix (podman
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# backend) stays at the top level, shared across categories.
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hosts/<h>/ # configuration.nix + disk-config.nix (disko) + hardware-configuration.nix + secrets.nix
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secrets/<h>.yaml # sops-nix, age-encrypted per host
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scripts/deploy # config-agnostic deploy wrapper (all args mandatory)
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scripts/edit_secrets
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.sops.yaml # per-host encryption rules (admin key + each host's key)
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```
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A host = `common.nix` + the `services/**` modules it imports + its `hosts/<h>/configuration.nix`.
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`services/` modules are engine-agnostic and shared across hosts (e.g. `services/vpn/tailscale.nix`,
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`services/network/caddy.nix` used by jupiter and neptun).
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## Commands
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Eval/verify a config before deploying (eval only checks the module tree, not
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freeform config like pihole's TOML or a container's runtime):
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```
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nix eval --raw .#nixosConfigurations.<host>.config.system.build.toplevel.drvPath
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```
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Deploy (from a non-NixOS laptop too — runs nixos-rebuild/nixos-anywhere via `nix run`):
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```
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./scripts/deploy switch <config> <host> # daily rebuild + activate
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./scripts/deploy install <config> <host> # first install (nixos-anywhere, wipes OS disk)
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./scripts/deploy kexec <config> <host> # RO-root box (ZimaOS): kexec into a RAM installer first
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sudo ./scripts/deploy kexec-local [--yes] # kexec THIS box (no ssh); confirm prompt unless --yes
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./scripts/deploy image mercury # build the aarch64 SD image
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./scripts/deploy flash mercury /dev/sdX # build + write SD + drop the sops age key
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```
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Both password prompts are auto-filled from the "HomeLab" Proton Pass vault, keyed by
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**`<config>`, not `<host>`** — items `darman@<config>` (sudo) and `root@<config>` (ssh).
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A *trashed* Proton Pass item with the same title shadows the active one and yields an
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empty password, so the script resolves the title among `--filter-state active` items
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first; a plain `pass-cli item view --item-title` silently returns the trashed copy and
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you get an interactive prompt with no explanation.
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`HOMELAB_KEXEC_TARBALL` (+ `_CPIO` / `_GZIP`) makes `kexec`/`kexec-local` reuse a
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prebuilt installer instead of rebuilding ~500MB. The VM test below uses this.
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Secrets (needs the admin age key at `~/.config/sops/age/keys.txt`):
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```
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./scripts/edit_secrets secrets/<host>.yaml
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```
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Test a service config BEFORE touching hardware — always do this for nontrivial changes:
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```
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# x86 QEMU VM of mercury's DNS/DHCP stack (fast; validates pihole/unbound at runtime)
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nix build .#nixosConfigurations.mercury-vm.config.system.build.vm -o result
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./result/bin/run-mercury-vm-vm # ssh -p 2223 darman@localhost (pw: test)
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# jupiter services as a VirtualBox OVA
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nix build .#nixosConfigurations.jupiter-vbox.config.system.build.virtualBoxOVA
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# end-to-end VM test of `deploy kexec-local` (~45s once the tarball is built)
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nix build .#checks.x86_64-linux.kexec-local -L
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```
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`checks.kexec-local` is the only way to exercise `kexec-local` at all: it jumps the
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machine you are typing at, so it cannot be rehearsed on real hardware and a failure
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looks exactly like a slow boot. It asserts the box actually left the old kernel
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(SSH drops then returns), came back as `nixos-installer`, lost its old `/run`, and
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kept its ssh host key. Run it after ANY change to the kexec paths.
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## Secrets (sops-nix)
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- Each `secrets/<host>.yaml` is encrypted to the **admin** key (edit) + that **host's**
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key (runtime decrypt); rules in `.sops.yaml`. Private keys live OFF-repo:
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`~/.config/sops/age/keys.txt` (admin), `~/.config/homelab/<host>/` (host keys).
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- jupiter/neptun decrypt with their **ssh host key** (`ssh-to-age` recipient), shipped at
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install via `nixos-anywhere --extra-files`.
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- mercury (SD image, no `--extra-files`) uses a **dedicated age key** at
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`/var/lib/sops-nix/age.txt` — `./scripts/deploy flash` writes it to the ext4 root partition.
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- A service password that must come from sops but whose module has no `passwordFile`
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hook (pihole, adguard) is injected via `sops.templates` → an env file → the service
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(`FTLCONF_*` for pihole). See `hosts/mercury/configuration.nix`.
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## Non-obvious gotchas (all learned the hard way)
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- **aarch64 (mercury)**: the x86 laptop needs `extra-platforms = aarch64-linux` in
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`/etc/nix/nix.custom.conf` (NOT `/etc/nix/nix.conf` — Determinate Nix regenerates that)
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+ `qemu-user-static-binfmt`, else emulated builds fail with "platform mismatch". Or
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build on the Pi with `--build-host darman@<ip>`.
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- **pihole on mercury is a CONTAINER** (`services/network/pihole.nix`, official image, host
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networking, caps NET_ADMIN/NET_RAW/SYS_NICE/CHOWN, `FTLCONF_*` env config). The native
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`services.pihole-ftl` module **segfaults on the Pi 3B+ aarch64** — do not switch back.
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- **`services.unbound.resolveLocalQueries = false`** is required: unbound listens on
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:5335, so leaving it true points the host's resolv.conf at 127.0.0.1:**53** with nothing
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there → boot-time DNS deadlock (starves image pulls / list downloads). Host resolves via
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upstream `networking.nameservers`; pihole forwards to unbound explicitly at `127.0.0.1#5335`.
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- **Remote deploy pushes unsigned closures**: hosts set `nix.settings.trusted-users =
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[ "root" "@wheel" ]` (in common.nix) so a laptop-built closure is accepted by the target.
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- **jupiter**: `boot.kernelParams = [ "reboot=pci" ]` (warm reboot hangs on that board);
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eMMC initrd modules pinned in `configuration.nix` (generate-config misses them); the
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16TB×2 **RAID0** data lives on `/mnt/data` with `nofail`, kept OUT of disko (never wiped).
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- **terra: `./scripts/deploy kexec-local` hangs hard — do not use it there.** Confirmed
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on real hardware: kexec's `device_shutdown()` pass runs (SCSI disks sync fine in the
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log), then the machine goes dark and never comes back — `journalctl --list-boots`
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showed a ~15min gap before the next boot, i.e. a genuine hang needing a manual power
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cycle, not a slow jump. Near-certainly amdgpu (RX 6800 XT): discrete AMD GPUs are known
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to hang during kexec's device-shutdown pass with no clean handoff before the jump —
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same class of issue as jupiter's `reboot=pci` workaround, just fatal here instead of
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slow. Use `./scripts/deploy install terra localhost` instead (README's "First install
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on terra" section) — it detects it isn't inside a live installer yet and reboots via
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a real `systemctl reboot` + systemd-boot one-shot `findiso=` entry, not kexec.
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- **`./scripts/deploy install <config> localhost`'s behavior depends on `uname -n`**
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(`is_live_installer()`): on a real running OS it builds `installer-iso`, stages it
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locally, and reboots into it (`local_install_prepare_and_reboot()`); only inside
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`nixos-installer` (kexec) or `homelab-installer` (installer-iso) does it actually run
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disko + `nixos-install`. `installer-iso`'s `homelab-auto-install.service` closes the
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loop: it reads `homelab.install=<config>` back off `/proc/cmdline` (set by the prepare
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step) and re-runs the identical command itself once `homelab-checkout.service` has
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cloned the repo — the whole reinstall is one command and unattended after the first
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reboot. It confirms (type `yes`) before rebooting, like `flash`/`kexec-local`; `--yes`
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skips that and is what the ISO passes itself. It always ASKS where to stage the iso
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file (never auto-picks — the wrong disk here is destroyed mid-install);
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`HOMELAB_INSTALLER_STAGE_DIR` skips the prompt for scripted use. Both this and
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`kexec-local` self-elevate via `sudo` (`require_root()`) rather than requiring you to
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prefix the command yourself.
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- **terra runs Limine, not systemd-boot** — `bootctl set-oneshot` is useless there
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(`bootctl status` lists `✗ One-shot entry control`, and CachyOS's pacman hooks
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regenerate `limine.conf` anyway). `local_install_prepare_and_reboot()` therefore
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picks its one-shot mechanism at runtime: a systemd-boot loader entry when
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`$BOOT/loader/entries` exists, otherwise `arm_efi_bootnext()` — a temporary UEFI
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entry that EFI-stub-boots the kernel off the ESP, armed via the firmware's
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`BootNext`. Created with `efibootmgr --create-only` (NOT `--create`, which pushes
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it to the front of `BootOrder` and would make a wiped installer the permanent
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default if anything went wrong). BootNext is spent by that one boot, so a failed
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attempt still comes back on the normal bootloader. The EFI-stub path needs the
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kernel on the **ESP** itself, not on a separate XBOOTLDR — hence `--print-esp-path`
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rather than `--print-boot-path` in that mode. `homelab-auto-install.service` deletes
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the leftover NVRAM entry as soon as it boots; both it and the script match the label
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`Homelab Installer` EXACTLY (a prefix match would delete the Windows or Limine entry).
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- **The staging-dir guard must fail CLOSED, and `findmnt` needs `--nofsroot`**: on btrfs
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`findmnt -no SOURCE` prints `/dev/sdb2[/@]`, which `lsblk` cannot open, so a naive
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parent-device lookup comes back empty. Treating empty as "different disk" silently
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allowed staging the iso on the very disk disko then wiped — terra's CachyOS root is
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exactly that layout, so it hit the live case. `disks_backing()` (`lsblk -rnso
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NAME,TYPE`) returns EVERY whole-disk ancestor because LVM/RAID can span several
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(`/mnt/ssd_01` → sdd + sde), and an empty result is a hard error, not a pass. btrfs
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staging is refused outright: stage-1 mounts a btrfs volume's TOP level, so an iso
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inside a subvolume is unreachable via `findiso=`.
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- **`findiso=` must keep its leading slash**: stage-1 tests `[ -e "/findiso$isoPath" ]`,
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so stripping the mountpoint prefix off a stagedir whose mountpoint is `/` yields
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`var/tmp/x.iso` → `/findisovar/tmp/x.iso` → emergency shell, after you have already
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rebooted out of the working OS.
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- **The auto-install needs the host key shipped to it, and a `$HOME`**: the ISO is built
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from a public repo with no credentials, so `local_install_prepare_and_reboot()` copies
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the key onto the boot partition and passes that partition's PARTUUID as
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`homelab.keypart=`; the service mounts it and drops the key in
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`/root/.config/homelab/<config>/` before running the install. Also, systemd does NOT
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set `$HOME` for a system service without `User=` (`SetLoginEnvironment=` defaults to
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false), and `scripts/deploy` runs under `set -u` — hence `$KEYDIR` instead of a bare
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`$HOME`, plus `Environment=HOME=/root` on the unit.
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- **`installer-iso` must enable `experimental-features` itself.** `installation-cd-minimal`
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leaves them unset, so `nix run` and `nixos-install --flake` both die with "experimental
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Nix feature 'nix-command' is disabled". The nixos-images `kexec` installer sets them
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itself, which is why the same `install <config> localhost` branch worked after
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`kexec-local` but not from the ISO.
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- **disko/nixos-anywhere run as `nix run .#disko` / `.#nixos-anywhere`**, from this
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flake's locked inputs — not `nix run github:...`. They execute while a disk is being
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wiped, so the revision must be the reviewed one in `flake.lock`, and it has to resolve
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without network.
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- **disko wipes only the OS disk** named in `hosts/<h>/disk-config.nix`; data disks are
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plain `fileSystems` in `configuration.nix`.
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- `nixos-anywhere`/kexec needs a writable root; **ZimaOS root is read-only**, hence the
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`./scripts/deploy kexec` step that streams a RAM installer (with static cpio/gzip since
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ZimaOS lacks them).
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- **`kexec/run` jumps ~6s AFTER it returns**: nixos-images' `kexec-run.sh` ends with
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`nohup sh -c "sleep 6 && $SCRIPT_DIR/kexec -e" &`. So the staging dir must OUTLIVE the
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script — an `rm -rf` in an EXIT trap deletes the binary that performs the jump and the
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box silently stays on the old kernel. `kexec-local` clears its trap before jumping and
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then sleeps 60s on purpose. Covered by `checks.kexec-local`.
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- **The kexec installer KEEPS the box's ssh host key**: `kexec-run.sh` copies
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`/etc/ssh/ssh_host_*` into the appended initrd and `restore-remote-access.nix` installs
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them back. So do NOT `ssh-keygen -R` after a kexec — the key does not change, and
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clearing it just throws away the known_hosts record.
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- **`kexec-local` stages on `/var/tmp`, not `/tmp`**: `kexec-run.sh` appends a fresh cpio
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to `kexec/initrd` in place and execs binaries from that dir, so a size-capped or
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`noexec` tmpfs gives a half-written initrd or a bare "Permission denied".
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