Make zsh install conditional.

nix/configuration/hosts/neelix/default.nix

@@ -31,4 +31,5 @@
   me.lvfs.enable = true;
   me.sound.enable = true;
   me.zrepl.enable = true;
+  me.zsh.enable = true;
 }

nix/configuration/hosts/odo/default.nix

@@ -58,4 +58,5 @@
   me.wasm.enable = true;
   me.waybar.enable = true;
   me.zrepl.enable = true;
+  me.zsh.enable = true;
 }

nix/configuration/roles/zsh/default.nix

@@ -55,36 +55,51 @@ in
 {
   imports = [ ];
 
-  environment.systemPackages = with pkgs; [
+  options.me = {
-    zsh
+    zsh.enable = lib.mkOption {
-  ];
+      type = lib.types.bool;
-
+      default = false;
-  users.users.talexander.shell = pkgs.zsh;
+      example = true;
-  environment.shells = with pkgs; [ zsh ];
+      description = "Whether we want to install zsh.";
-
-  programs.zsh = {
-    enable = true;
-  };
-
-  home-manager.users.talexander =
-    { pkgs, ... }:
-    {
-      home.file.".zshrc" = {
-        source = "${zshrc}";
-      };
-    };
-
-  environment.persistence."/persist" = lib.mkIf (!config.me.buildingIso) {
-    hideMounts = true;
-    users.talexander = {
-      directories = [
-        {
-          directory = ".histdb";
-          user = "talexander";
-          group = "talexander";
-          mode = "0700";
-        }
-      ];
     };
   };
+
+  config = lib.mkIf config.me.zsh.enable (
+    lib.mkMerge [
+      {
+        environment.systemPackages = with pkgs; [
+          zsh
+        ];
+
+        users.users.talexander.shell = pkgs.zsh;
+        environment.shells = with pkgs; [ zsh ];
+
+        programs.zsh = {
+          enable = true;
+        };
+
+        home-manager.users.talexander =
+          { pkgs, ... }:
+          {
+            home.file.".zshrc" = {
+              source = "${zshrc}";
+            };
+          };
+
+        environment.persistence."/persist" = lib.mkIf (!config.me.buildingIso) {
+          hideMounts = true;
+          users.talexander = {
+            directories = [
+              {
+                directory = ".histdb";
+                user = "talexander";
+                group = "talexander";
+                mode = "0700";
+              }
+            ];
+          };
+        };
+      }
+    ]
+  );
 }