Add lxc-tor-relay build type with nyx monitoring

New tor-relay build type (currently lxc-only) running a plain Tor
middle relay via modules/tor/enable-relay.nix, plus nyx for
interactive monitoring over the relay's control socket.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

AGENTS.md

@@ -7,7 +7,7 @@ servers and workstation.
 
 The flake exposes NixOS configurations named `<platform>-<buildtype>`
 (platforms: `linode`, `proxmox`, `lxc`; build types: `minimal`, `nix-cache`,
-`server`, `docker`, `gui`, `pxe-boot`, `tailscale-exit-node`), generated from `modules/platforms/*`
+`server`, `docker`, `gui`, `pxe-boot`, `tailscale-exit-node`, `tor-relay`), generated from `modules/platforms/*`
 and `modules/build-types/*` by the `mkTarget` function in `flake.nix`. Not
 every combination is built — `pxe-boot` has no `linode` variant. See
 `README.md` for the full current target list; treat `flake.nix` as the

CLAUDE.md

@@ -160,9 +160,10 @@ nixosSystem {
 ```
 
 Platforms: `linode`, `proxmox`, `lxc`. Build types: `minimal`, `nix-cache`,
-`server`, `docker`, `gui`, `pxe-boot`, `tailscale-exit-node`. Not every
+`server`, `docker`, `gui`, `pxe-boot`, `tailscale-exit-node`, `tor-relay`. Not
-combination is built — e.g. `pxe-boot` has no `linode` variant (PXE/DHCP/TFTP
+every combination is built — e.g. `pxe-boot` has no `linode` variant
-need LAN L2 adjacency a Linode VPS doesn't have). Treat `flake.nix`'s
+(PXE/DHCP/TFTP need LAN L2 adjacency a Linode VPS doesn't have), and
+`tor-relay` currently only exists as `lxc-tor-relay`. Treat `flake.nix`'s
 `generatedTargets` as the source
 of truth for which hosts exist — `README.md`, `AGENTS.md`,
 `docs/flake-lock-automation.md`, and the CI eval workflows
@@ -190,7 +191,7 @@ removing a host.
   `vzdump` backup-archive metadata this doesn't have), no install step —
   see `docs/auto-installer.md`.
 - `modules/build-types/*.nix` — what a system is for:
-  minimal/server/docker/gui/pxe-boot/nix-cache/tailscale-exit-node.
+  minimal/server/docker/gui/pxe-boot/nix-cache/tailscale-exit-node/tor-relay.
 - `modules/common/configuration.nix` — base NixOS config imported by every
   host: locale, users, nix settings, git.
 - `modules/common/home.nix` / `hosts/nixos/home.nix` — Home Manager config for
@@ -225,7 +226,8 @@ removing a host.
   and `environmentFile`; used by `hosts/server/host.nix` and
   `hosts/nix-cache/host.nix` to avoid duplicating that boilerplate.
 - `modules/tailscale/`, `modules/docker/`, `modules/networking/`,
-  `modules/traefik/`, `modules/services/*` — single-purpose, single-host
+  `modules/traefik/`, `modules/tor/`, `modules/services/*` — single-purpose,
+  single-host
   feature modules (e.g. `docker/enable-service.nix`,
   `services/zfs/enable-service.nix`). Grep `modules/build-types/*.nix` for
   each build type's `imports` list to see which modules apply where.

README.md

@@ -10,11 +10,11 @@ pieces composed in `flake.nix`:
 
 - **Platforms** (what it runs on): `linode`, `proxmox`, `lxc`
 - **Build types** (what it's for): `minimal`, `nix-cache`, `server`, `docker`,
-  `gui`, `pxe-boot`, `tailscale-exit-node`
+  `gui`, `pxe-boot`, `tailscale-exit-node`, `tor-relay`
 
 Not every combination exists — `pxe-boot` has no `linode` variant, since
-PXE/DHCP/TFTP need LAN L2 adjacency that a Linode VPS doesn't have. The full
+PXE/DHCP/TFTP need LAN L2 adjacency that a Linode VPS doesn't have, and
-list:
+`tor-relay` currently only exists as `lxc-tor-relay`. The full list:
 
 | Target | Purpose |
 | --- | --- |
@@ -27,6 +27,7 @@ list:
 | `linode-gui` / `proxmox-gui` / `lxc-gui` | Cinnamon desktop workstation — previously the flat `nixos` target |
 | `proxmox-pxe-boot` / `lxc-pxe-boot` | HTTP/iPXE boot asset host — previously the flat `pxe-boot` target |
 | `linode-tailscale-exit-node` / `proxmox-tailscale-exit-node` / `lxc-tailscale-exit-node` | Tailscale exit node |
+| `lxc-tor-relay` | Tor middle relay |
 
 Which variant of a given buildtype is actually deployed isn't tracked
 anywhere in this repo — that's live infrastructure state, not something a

docs/auto-installer.md

@@ -19,7 +19,7 @@ see "LXC hosts" immediately below for why those are different.**
 ## LXC hosts
 
 `lxc-*` targets (`lxc-minimal`, `lxc-nix-cache`, `lxc-server`, `lxc-docker`,
-`lxc-gui`, `lxc-pxe-boot`, `lxc-tailscale-exit-node`) are **not** installed via `auto-install.sh` — the
+`lxc-gui`, `lxc-pxe-boot`, `lxc-tailscale-exit-node`, `lxc-tor-relay`) are **not** installed via `auto-install.sh` — the
 interactive menu deliberately excludes them. Don't try to select one there;
 `nixos-install` would bind-mount `/` onto `/mnt` (LXC containers have no raw
 disk to partition) and then refuse to touch the filesystem it's currently

flake.nix

@@ -98,6 +98,8 @@
         linode-tailscale-exit-node = mkTarget { platform = "linode"; buildType = "tailscale-exit-node"; hostPath = ./hosts/tailscale-exit-node/host.nix; };
         proxmox-tailscale-exit-node = mkTarget { platform = "proxmox"; buildType = "tailscale-exit-node"; hostPath = ./hosts/tailscale-exit-node/host.nix; };
         lxc-tailscale-exit-node = mkTarget { platform = "lxc"; buildType = "tailscale-exit-node"; hostPath = ./hosts/tailscale-exit-node/host.nix; };
+
+        lxc-tor-relay = mkTarget { platform = "lxc"; buildType = "tor-relay"; hostPath = ./hosts/tor-relay/host.nix; };
       };
 
       # Auto-install environments (migrated from the former nix-auto-installer

hosts/tor-relay/host.nix

@@ -0,0 +1,12 @@
+_:
+
+{
+  networking.hostName = "tor-relay";
+
+  # No networking.hostId: only ZFS-touching hosts (server, docker) need one
+  # for pool-import safety, and this host does neither.
+
+  # A genuinely new host (not a pre-refactor carry-over), so it tracks the
+  # flake's current nixpkgs release rather than being pinned to an older one.
+  system.stateVersion = "26.05";
+}

modules/build-types/tor-relay.nix

@@ -0,0 +1,7 @@
+{ ... }:
+
+{
+  imports = [
+    ../tor/enable-relay.nix
+  ];
+}

modules/tor/enable-relay.nix

@@ -0,0 +1,35 @@
+{ pkgs, vars, ... }:
+
+{
+  services.tor = {
+    enable = true;
+
+    # Opens settings.ORPort (and DirPort, unset here) in the firewall —
+    # see the nixpkgs tor module's own networking.firewall.mkIf block.
+    openFirewall = true;
+
+    relay = {
+      enable = true;
+      # Plain middle/guard relay, not "exit" — relays onion traffic between
+      # other Tor nodes without ever making requests to the public internet
+      # on a user's behalf, avoiding the abuse complaints and legal exposure
+      # an exit node invites.
+      role = "relay";
+    };
+
+    settings.ORPort = vars.ports.torRelayOrPort;
+
+    # Unix control socket at /run/tor/control (GroupWritable, group "tor")
+    # -- what nyx below actually monitors the relay through. Nyx's own
+    # default control-socket path (/var/run/tor/control) resolves to the
+    # same place, so no extra nyx config is needed.
+    controlSocket.enable = true;
+  };
+
+  # Lets the primary user's shell session read/write the control socket
+  # above without being root -- otherwise nyx fails to authenticate against
+  # it at all.
+  users.users.${vars.primaryUser}.extraGroups = [ "tor" ];
+
+  environment.systemPackages = [ pkgs.nyx ];
+}

variables.nix

@@ -137,6 +137,14 @@
     # shortcuts on the gui build type (hosts/nixos/home.nix).
     pveWeb = 8006;
     pbsWeb = 8007;
+
+    # Tor relay's ORPort — the port other Tor relays connect to for onion
+    # routing traffic (modules/tor/enable-relay.nix). Tor's own conventional
+    # default; opened via services.tor.openFirewall rather than
+    # networking.firewall.allowedTCPPorts directly, but kept here anyway so
+    # it's not a bare literal duplicated between the relay's settings and
+    # anything else that ever needs to reference it.
+    torRelayOrPort = 9001;
   };
 
   # .raw disk image size for every proxmox-* host's standalone Disko image