roam/homey.org

homey

• Architecture
• Deployment
• Conventions
• Gotchas
• Key Files
• TODOs
  • Enable chunked uploads to ATTIC

Architecture

NixOS homelab on Raspberry Pi 4 (8 GB). Domain: zakobar.com. Static IP: 192.168.1.100. nixpkgs pin: nixos-25.05.

Container runtime: Podman via virtualisation.oci-containers. All containers join the homey podman network (created by podman-homey-network.service in common.nix). Inter-container DNS via container names; Caddy proxies via 127.0.0.1:<port>.

Reverse proxy: Caddy with Cloudflare DNS-01 wildcard cert for *.zakobar.com. Built via pkgs.caddy.withPlugins with github.com/caddy-dns/cloudflare@v0.2.4 (resolved hash: sha256-pRrLBlYRaAyMYwPXeTy4WqWNRu/L9K6Mn2src11dGh8=). Each vhost generates a pair: HTTPS vhost + http:// vhost for cloudflared loopback. Authelia forward_auth uses /api/authz/forward-auth (v4.38+ endpoint, not legacy).

Auth stack: OpenLDAP ← Authelia (TOTP 2FA). Authelia config is rendered entirely at build time from Nix strings. A NIXOS_CONFIG_HASH env var on the container forces a restart whenever the config changes (bind-mounts resolve symlinks at start, so the running container would otherwise keep the old config).

Monitoring: Prometheus (9090) + node_exporter (9100) + systemd_exporter (9558) + Grafana (3002). Node Exporter Full dashboard pre-provisioned (fetchurl hash resolved: sha256-1DE1aaanRHHeCOMWDGdOS1wBXxOF84UXAjJzT5Ek6mM, ID 1860 rev 37). Grafana proxy auth: Authelia → Remote-User header → Caddy maps to X-WEBAUTH-USER → Grafana auto-signs-in. All reaching Grafana are confirmed admins (Authelia enforces two_factor + admins group).

Uptime Kuma sync: a Python oneshot service runs after container start. Hash-gated — only re-syncs when the monitor JSON changes. Supports keyword (keyword monitor type) and maxretries fields beyond the basic name/url/interval.

Attic (self-hosted Nix binary cache): cache name main, public key main:9SZt/6plBU7jjQzz90J7O011I13hmJvOMYouxNqExNQ=, endpoint https://attic.zakobar.com/main. Setup completed 2026-05-30. NAR content not backed up — reproducible from source. Tokens are stateless JWTs; regenerate with same atticadm command if lost.

Eurovision Vote: Django app sourced from external flake github:anerisgreat/eurovote, wrapped by modules/services/eurovote.nix. Uses DynamicUser + StateDirectory so systemd owns /var/lib/eurovote/; no tmpfiles entry needed.

Backup: Restic daily at 03:00 to S3 (Backblaze B2, bucket zakobar-home-backup). Pre-hook: Nextcloud maintenance mode on + pg_dump. Post-hook: maintenance mode off. Manual offload: restic copy to local disk. NAR content and media excluded.

Reliability hardening in hosts/pi-main/default.nix: hardware watchdog (bcm2835_wdt), WiFi power save disabled, network watchdog timer, zramSwap zstd 25%, Nix build-dir on external HD.

Bootstrap: pi-main-bootstrap config builds an SD image (sd-image-aarch64.nix) for first flash.

Deployment

Always deploy from the dev machine using the dev shell command:

# Enter the dev shell first:
nix develop

# Then run:
homey-deploy-rpi-main

Equivalent command (if not in dev shell):

nixos-rebuild switch \
  --flake .#pi-main \
  --target-host admin@192.168.1.100 \
  --build-host admin@192.168.1.100 \
  --use-remote-sudo

Both --target-host and --build-host point to the Pi — the build happens ON the Pi (uses Attic cache at attic.zakobar.com). The dev machine only supplies the flake source; it does not build locally.

NEVER run nixos-rebuild directly on the Pi (/home/admin/homey/ is a stale mirror, not the authoritative source). The dev machine at /home/aner/projects/selfhosted/homey/ is the source of truth.

Nix evaluates git-tracked files from the flake. New/modified files must be at least git add-ed (staged) before deploying, or they will be invisible to Nix. Untracked files are silently ignored.

Conventions

homeyConfig specialArgs (passed to every module): domain, organization, timezone. Never hardcode domain strings.

users.mutableUsers = false — all user config must be declared in Nix.

Secret injection pattern: LoadCredential stages sops-decrypted file into $CREDENTIALS_DIRECTORY before Exec*; shell script reads and exports. Ephemeral env files written to /run/ and cleaned up in ExecStopPost / postStop.

Authelia accessControlRules: sorted by priority at build time (lower = first). Authelia stops at first match, so more-specific rules must have lower priority. Ranges: 0=bypass, 10–19=blanket bypass, 20–49=admin two_factor+deny pairs, 50–64=one_factor open, 65–79=per-path (resources + subject combos).

accessControlRules option is declared unconditionally (not inside mkIf cfg.enable) so any module can contribute rules even when Authelia is disabled. Same pattern for homey.monitoring.monitors.

Attic token generation: run atticadm make-token inside the container. Tokens are stateless; losing one means just regenerating it with the same command.

DynamicUser services (Eurovision Vote): secrets must be mode 0444 (not 0400) because DynamicUser gets a random UID that cannot be pre-assigned as owner.

Caddy Cloudflare plugin secrets: uses LoadCredential + ExecStart override (clears list with empty string first, then sets the real start command) to export CLOUDFLARE_API_TOKEN before exec-ing caddy.

Stirling-PDF login disable: DOCKER_ENABLE_SECURITY=false is build-time only. To disable the runtime login page, also set SECURITY_ENABLELOGIN=false.

Gotchas

hdparm APM udev rule was removed — USB-SATA bridges often don't support APM commands and hdparm hangs indefinitely, causing boot-time crashes.

storage.nix config is gated on lib.mkIf (cfg.device ! "")= — if homey.storage.device is empty string, the mount and all tmpfiles rules are skipped. Useful during initial setup.

Grafana login form disabled (disable_login_form = true) — recovery requires re-enabling it in the Nix config. All proxy-auth users are auto-assigned Admin role (safe because Authelia already restricts to admins group).

Authelia config bind-mount gotcha: NixOS resolves the symlink to the nix store path at container start. Without NIXOS_CONFIG_HASH env var, a config change would not take effect until manual container restart.

WiFi network name: Zakobar. sops secret key: wifi/psk. The secret file must contain exactly one line: wifi_psk=<password>.

Attic: writing ephemeral TOML config via ExecStartPre shell script to /run/attic-config.toml. JWT secret interpolated into the TOML at runtime.

First deployment of a new container pulls the image during nixos-rebuild switch, which can block the activation for several minutes (e.g. stirling-pdf ~2 GB image took ~6 min on Pi). This is expected — not a hang.

Key Files

• flake.nix — module list, mkHost builder, homeyConfig specialArgs, rpi4Headless hardware snippet
• hosts/pi-main/default.nix — enabled services, static IP, WiFi, reliability hardening, Attic substituter config
• shells/defaultShell.nix — dev shell with homey-deploy-rpi-main and other helper commands
• modules/caddy.nix — virtualHosts option, dual vhost generation, Authelia forward_auth snippet
• modules/services/authelia.nix — access control rule rendering, accessControlRules option (unconditional)
• modules/services/uptime-kuma.nix — homey.monitoring.monitors option (unconditional), sync script
• modules/services/attic.nix — Nix binary cache, JWT token config, netrc injection for Nix daemon
• modules/services/stirling-pdf.nix — PDF tools (merge/split/OCR/etc), port 8084, auth disabled via SECURITY_ENABLELOGIN=false
• modules/monitoring.nix — Prometheus + Grafana, proxy auth wiring, Node Exporter Full dashboard
• modules/common.nix — Nix settings, podman network creation, sops global config
• modules/storage.nix — external HD mount, extraDirs option
• modules/backup.nix — Restic, pre/post hooks, extraPaths option

TODOs

TODO Enable chunked uploads to ATTIC

Should be able to do this

1. Server side – add to `attic.toml`:

[store]
# Enable the chunk‑aware upload handler
enableChunkedUpload = true
# Optional: limit the size of each chunk (default 10 MiB)
maxChunkSize = 5_000_000   # 5 MiB per chunk