Centralize shared values into variables.nix

One file (variables.nix) holding every value that was previously
hardcoded and repeated across modules: LAN domain/CIDR, home/tailnet
domains, cross-host references (nix-cache substituter hostname, NFS
server hostname, remote-builder user), PXE/PBS IPs, timezone, and the
primary username.

Wired in via flake.nix's specialArgs (and home-manager's
extraSpecialArgs for the two home.nix files), so any module picks it
up by just adding `vars` to its function arguments — no explicit
import needed. Two hosts (nix-cache, server) now derive their own
networking.hostName from the same variable other hosts use to reach
them, so there's exactly one place to change either identifier.

Purely mechanical: every substituted value matches what was already
there, confirmed by identical toplevel .drv paths for all 17 targets
before and after.

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

hosts/nix-cache/host.nix

@@ -1,7 +1,7 @@
-{ config, ... }:
+{ config, vars, ... }:
 
 {
-  networking.hostName = "nix-cache";
+  networking.hostName = vars.nixCacheHost;
 
   sops.secrets."beszel-token".sopsFile = ../../secrets/nix-cache.yaml;
   sops.templates."nix-cache-beszel.env".content = ''

hosts/nixos/home.nix

@@ -1,16 +1,16 @@
-{ config, pkgs, lib, ... }:
+{ config, pkgs, lib, vars, ... }:
 
 {
 
-    imports = [
+  imports = [
     ../../modules/common/aliases.nix
   ];
 
-  home.username = "nixos";         # your actual username
-  home.homeDirectory = "/home/nixos";
-  home.stateVersion = "25.05";        # match your NixOS stateVersion
+  home.username = vars.primaryUser;
+  home.homeDirectory = "/home/${vars.primaryUser}";
+  home.stateVersion = "25.05"; # match your NixOS stateVersion
 
-  programs.home-manager.enable = true;  # mandatory to activate HM
+  programs.home-manager.enable = true; # mandatory to activate HM
 
   # Optional: packages
   home.packages = with pkgs; [
@@ -18,7 +18,7 @@
     vim
     tmux
     nextcloud-client
-#    vscode
+    #    vscode
     chromium
   ];
 
@@ -29,51 +29,51 @@
 
   # Optional: enable bash (or zsh, fish...)
   programs.bash.enable = true;
-    services.nextcloud-client = {
+  services.nextcloud-client = {
     enable = true;
     # Optionally start in background directly
     startInBackground = true;
   };
-home.file = {
-  ".local/share/applications/proxmox-chromium-app.desktop".text = ''
-    [Desktop Entry]
-    Type=Application
-    Name=Proxmox (Chromium)
-    Exec=chromium --app=https://pve.sweet.home:8006 --window-size=1920,1080 --window-position=0,0
-    Icon=/home/nixos/.local/share/icons/proxmox.png
-    Terminal=false
-    Categories=Hypervisor;
-    StartupWMClass=PVE
-  '';
-  ".local/share/applications/pbs-chromium-app.desktop".text = ''
-    [Desktop Entry]
-    Type=Application
-    Name=Proxmox Backup Server (Chromium)
-    Exec=chromium --app=https://192.168.2.108:8007 --window-size=1920,1080 --window-position=0,0
-    Icon=/home/nixos/.local/share/icons/proxmox.png
-    Terminal=false
-    Categories=backup;
+  home.file = {
+    ".local/share/applications/proxmox-chromium-app.desktop".text = ''
+      [Desktop Entry]
+      Type=Application
+      Name=Proxmox (Chromium)
+      Exec=chromium --app=https://pve.${vars.homeDomain}:8006 --window-size=1920,1080 --window-position=0,0
+      Icon=${config.home.homeDirectory}/.local/share/icons/proxmox.png
+      Terminal=false
+      Categories=Hypervisor;
+      StartupWMClass=PVE
+    '';
+    ".local/share/applications/pbs-chromium-app.desktop".text = ''
+      [Desktop Entry]
+      Type=Application
+      Name=Proxmox Backup Server (Chromium)
+      Exec=chromium --app=https://${vars.pbsIp}:8007 --window-size=1920,1080 --window-position=0,0
+      Icon=${config.home.homeDirectory}/.local/share/icons/proxmox.png
+      Terminal=false
+      Categories=backup;
 
-  '';
-  ".local/share/applications/proxmox-firefox-app.desktop".text = ''
-    [Desktop Entry]
-    Type=Application
-    Name=Proxmox (Firefox)
-    Exec=firefox --new-instance https://pve.sweet.home:8006 --profile ProxmoxWebApp --window-size=1920,1080 --class ProxmoxWebApp
-    Icon=/home/nixos/.local/share/icons/proxmox.png
-    Terminal=false
-    Categories=Hypervisor;
-    StartupWMClass=PVE
-  '';
-  ".local/share/applications/pbs-firefox-app.desktop".text = ''
-    [Desktop Entry]
-    Type=Application
-    Name=Proxmox Backup Server (Firefox)
-    Exec=firefox --new-window https://192.168.2.108:8007 --profile PbsWebApp --window-size=1920,1080 --class PbsWebApp
-    Icon=/home/nixos/.local/share/icons/proxmox.png
-    Terminal=false
-    Categories=backup;
-    StartupWMClass=PBS
-  '';
-};
-}
+    '';
+    ".local/share/applications/proxmox-firefox-app.desktop".text = ''
+      [Desktop Entry]
+      Type=Application
+      Name=Proxmox (Firefox)
+      Exec=firefox --new-instance https://pve.${vars.homeDomain}:8006 --profile ProxmoxWebApp --window-size=1920,1080 --class ProxmoxWebApp
+      Icon=${config.home.homeDirectory}/.local/share/icons/proxmox.png
+      Terminal=false
+      Categories=Hypervisor;
+      StartupWMClass=PVE
+    '';
+    ".local/share/applications/pbs-firefox-app.desktop".text = ''
+      [Desktop Entry]
+      Type=Application
+      Name=Proxmox Backup Server (Firefox)
+      Exec=firefox --new-window https://${vars.pbsIp}:8007 --profile PbsWebApp --window-size=1920,1080 --class PbsWebApp
+      Icon=${config.home.homeDirectory}/.local/share/icons/proxmox.png
+      Terminal=false
+      Categories=backup;
+      StartupWMClass=PBS
+    '';
+  };
+}

hosts/server/host.nix

@@ -1,7 +1,7 @@
-{ config, ... }:
+{ config, vars, ... }:
 
 {
-  networking.hostName = "server";
+  networking.hostName = vars.nfsServerHost;
   networking.hostId = "6689f93e";
 
   sops.secrets."beszel-token".sopsFile = ../../secrets/server.yaml;
@@ -13,7 +13,7 @@
     #DOCKER_HOST = "tcp://docker-socket-proxy:2375";
     #HUB_URL = "http://docker.sweet.home:8090";
     KEY = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIFPR9kwtC4TAeTRu46A7+opZsYpxqkRJ+x/ZyB2GWCeG";
-    EXTRA_FILESYSTEMS = "/tank/docker/volumes";
+    EXTRA_FILESYSTEMS = "${vars.storageRoot}/docker/volumes";
     LOG_LEVEL = "debug";
   };
   services.beszel.agent.environmentFile = config.sops.templates."server-beszel.env".path;