nix: vms for testing ghostty

.gitignore

@@ -17,3 +17,4 @@ test/cases/**/*.actual.png
 glad.zip
 /Box_test.ppm
 /Box_test_diff.ppm
+/ghostty.qcow2

CONTRIBUTING.md

@@ -77,3 +77,100 @@ pull request will be accepted with a high degree of certainty.
 > **Pull requests are NOT a place to discuss feature design.** Please do
 > not open a WIP pull request to discuss a feature. Instead, use a discussion
 > and link to your branch.
+
+## Nix Virtual Machines
+
+Several Nix virtual machine definitions are provided by the project for testing
+and developing Ghostty against multiple different Linux desktop environments.
+
+Running these requires a working Nix installation, either Nix on your
+favorite Linux distribution, NixOS, or macOS with nix-darwin installed. Further
+requirements for macOS are detailed below.
+
+VMs should only be run on your local desktop and then powered off when not in
+use, which will discard any changes to the VM.
+
+The VM definitions provide minimal software "out of the box" but additional
+software can be installed by using standard Nix mechanisms like `nix run nixpkgs#<package>`.
+
+### Linux
+
+1. Check out the Ghostty source and change to the directory.
+2. Run `nix run .#<vmtype>`. `<vmtype>` can be any of the VMs defined in the
+   `nix/vm` directory (without the `.nix` suffix) excluding any file prefixed
+   with `common` or `create`.
+3. The VM will build and then launch. Depending on the speed of your system, this
+   can take a while, but eventually you should get a new VM window.
+4. The Ghostty source directory should be mounted to `/tmp/shared` in the VM. Depending
+   on what UID and GID of the user that you launched the VM as, `/tmp/shared` _may_ be
+   writable by the VM user, so be careful!
+
+### macOS
+
+1. To run the VMs on macOS you will need to enable the Linux builder in your `nix-darwin`
+   config. This _should_ be as simple as adding `nix.linux-builder.enable=true` to your
+   configuration and then rebuilding. See [this](https://nixcademy.com/posts/macos-linux-builder/)
+   blog post for more information about the Linux builder and how to tune the performance.
+2. Once the Linux builder has been enabled, you should be able to follow the Linux instructions
+   above to launch a VM.
+
+### Custom VMs
+
+To easily create a custom VM without modifying the Ghostty source, create a new
+directory, then create a file called `flake.nix` with the following text in the
+new directory.
+
+```
+{
+  inputs = {
+    nixpkgs.url = "nixpkgs/nixpkgs-unstable";
+    ghostty.url = "github:ghostty-org/ghostty";
+  };
+  outputs = {
+    nixpkgs,
+    ghostty,
+    ...
+  }: {
+   nixosConfigurations.custom-vm = ghostty.create-gnome-vm {
+     nixpkgs = nixpkgs;
+     system = "x86_64-linux";
+     overlay = ghostty.overlays.releasefast;
+     # module = ./configuration.nix # also works
+     module = {pkgs, ...}: {
+       environment.systemPackages = [
+         pkgs.btop
+       ];
+     };
+    };
+  };
+}
+```
+
+The custom VM can then be run with a command like this:
+
+```
+nix run .#nixosConfigurations.custom-vm.config.system.build.vm
+```
+
+A file named `ghostty.qcow2` will be created that is used to persist any changes
+made in the VM. To "reset" the VM to default delete the file and it will be
+recreated the next time you run the VM.
+
+### Contributing new VM definitions
+
+#### VM Acceptance Criteria
+
+We welcome the contribution of new VM definitions, as long as they meet the following criteria:
+
+1. The should be different enough from existing VM definitions that they represent a distinct
+   user (and developer) experience.
+2. There's a significant Ghostty user population that uses a similar environment.
+3. The VMs can be built using only packages from the current stable NixOS release.
+
+#### VM Definition Criteria
+
+1. VMs should be as minimal as possible so that they build and launch quickly.
+   Additional software can be added at runtime with a command like `nix run nixpkgs#<package name>`.
+2. VMs should not expose any services to the network, or run any remote access
+   software like SSH daemons, VNC or RDP.
+3. VMs should auto-login using the "ghostty" user.

flake.nix

@@ -31,38 +31,81 @@
     zig,
     ...
   }:
-    builtins.foldl' nixpkgs-stable.lib.recursiveUpdate {} (builtins.map (system: let
-      pkgs-stable = nixpkgs-stable.legacyPackages.${system};
-      pkgs-unstable = nixpkgs-unstable.legacyPackages.${system};
-    in {
-      devShell.${system} = pkgs-stable.callPackage ./nix/devShell.nix {
-        zig = zig.packages.${system}."0.13.0";
-        wraptest = pkgs-stable.callPackage ./nix/wraptest.nix {};
-      };
+    builtins.foldl' nixpkgs-stable.lib.recursiveUpdate {} (
+      builtins.map (
+        system: let
+          pkgs-stable = nixpkgs-stable.legacyPackages.${system};
+          pkgs-unstable = nixpkgs-unstable.legacyPackages.${system};
+        in {
+          devShell.${system} = pkgs-stable.callPackage ./nix/devShell.nix {
+            zig = zig.packages.${system}."0.13.0";
+            wraptest = pkgs-stable.callPackage ./nix/wraptest.nix {};
+          };
 
-      packages.${system} = let
-        mkArgs = optimize: {
-          inherit optimize;
+          packages.${system} = let
+            mkArgs = optimize: {
+              inherit optimize;
 
-          revision = self.shortRev or self.dirtyShortRev or "dirty";
-        };
-      in rec {
-        ghostty-debug = pkgs-stable.callPackage ./nix/package.nix (mkArgs "Debug");
-        ghostty-releasesafe = pkgs-stable.callPackage ./nix/package.nix (mkArgs "ReleaseSafe");
-        ghostty-releasefast = pkgs-stable.callPackage ./nix/package.nix (mkArgs "ReleaseFast");
+              revision = self.shortRev or self.dirtyShortRev or "dirty";
+            };
+          in rec {
+            ghostty-debug = pkgs-stable.callPackage ./nix/package.nix (mkArgs "Debug");
+            ghostty-releasesafe = pkgs-stable.callPackage ./nix/package.nix (mkArgs "ReleaseSafe");
+            ghostty-releasefast = pkgs-stable.callPackage ./nix/package.nix (mkArgs "ReleaseFast");
 
-        ghostty = ghostty-releasefast;
-        default = ghostty;
-      };
+            ghostty = ghostty-releasefast;
+            default = ghostty;
+          };
 
-      formatter.${system} = pkgs-stable.alejandra;
+          formatter.${system} = pkgs-stable.alejandra;
 
-      # Our supported systems are the same supported systems as the Zig binaries.
-    }) (builtins.attrNames zig.packages))
+          apps.${system} = let
+            runVM = (
+              module: let
+                vm = import ./nix/vm/create.nix {
+                  inherit system module;
+                  nixpkgs = nixpkgs-stable;
+                  overlay = self.overlays.debug;
+                };
+                program = pkgs-stable.writeShellScript "run-ghostty-vm" ''
+                  SHARED_DIR=$(pwd)
+                  export SHARED_DIR
+
+                  ${pkgs-stable.lib.getExe vm.config.system.build.vm} "$@"
+                '';
+              in {
+                type = "app";
+                program = "${program}";
+              }
+            );
+          in {
+            wayland-cinnamon = runVM ./nix/vm/wayland-cinnamon.nix;
+            wayland-gnome = runVM ./nix/vm/wayland-gnome.nix;
+            wayland-plasma6 = runVM ./nix/vm/wayland-plasma6.nix;
+            x11-cinnamon = runVM ./nix/vm/x11-cinnamon.nix;
+            x11-gnome = runVM ./nix/vm/x11-gnome.nix;
+            x11-plasma6 = runVM ./nix/vm/x11-plasma6.nix;
+            x11-xfce = runVM ./nix/vm/x11-xfce.nix;
+          };
+        }
+        # Our supported systems are the same supported systems as the Zig binaries.
+      ) (builtins.attrNames zig.packages)
+    )
     // {
-      overlays.default = final: prev: {
-        ghostty = self.packages.${prev.system}.default;
+      overlays = {
+        default = self.overlays.releasefast;
+        releasefast = final: prev: {
+          ghostty = self.packages.${prev.system}.ghostty-releasefast;
+        };
+        debug = final: prev: {
+          ghostty = self.packages.${prev.system}.ghostty-debug;
+        };
       };
+      create-vm = import ./nix/vm/create.nix;
+      create-cinnamon-vm = import ./nix/vm/create-cinnamon.nix;
+      create-gnome-vm = import ./nix/vm/create-gnome.nix;
+      create-plasma6-vm = import ./nix/vm/create-plasma6.nix;
+      create-xfce-vm = import ./nix/vm/create-xfce.nix;
     };
 
   nixConfig = {

nix/vm/common-cinnamon.nix

@@ -0,0 +1,18 @@
+{...}: {
+  imports = [
+    ./common.nix
+  ];
+
+  services.xserver = {
+    displayManager = {
+      lightdm = {
+        enable = true;
+      };
+    };
+    desktopManager = {
+      cinnamon = {
+        enable = true;
+      };
+    };
+  };
+}

nix/vm/common-gnome.nix

@@ -0,0 +1,136 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}: {
+  imports = [
+    ./common.nix
+  ];
+
+  services.xserver = {
+    displayManager = {
+      gdm = {
+        enable = true;
+        autoSuspend = false;
+      };
+    };
+    desktopManager = {
+      gnome = {
+        enable = true;
+      };
+    };
+  };
+
+  environment.systemPackages = [
+    pkgs.gnomeExtensions.no-overview
+  ];
+
+  environment.gnome.excludePackages = with pkgs; [
+    atomix
+    baobab
+    cheese
+    epiphany
+    evince
+    file-roller
+    geary
+    gnome-backgrounds
+    gnome-calculator
+    gnome-calendar
+    gnome-clocks
+    gnome-connections
+    gnome-contacts
+    gnome-disk-utility
+    gnome-extension-manager
+    gnome-logs
+    gnome-maps
+    gnome-music
+    gnome-photos
+    gnome-software
+    gnome-system-monitor
+    gnome-text-editor
+    gnome-themes-extra
+    gnome-tour
+    gnome-user-docs
+    gnome-weather
+    hitori
+    iagno
+    loupe
+    nautilus
+    orca
+    seahorse
+    simple-scan
+    snapshot
+    sushi
+    tali
+    totem
+    yelp
+  ];
+
+  programs.dconf = {
+    enable = true;
+    profiles.user.databases = [
+      {
+        settings = with lib.gvariant; {
+          "org/gnome/desktop/background" = {
+            picture-uri = "file://${pkgs.ghostty}/share/icons/hicolor/512x512/apps/com.mitchellh.ghostty.png";
+            picture-uri-dark = "file://${pkgs.ghostty}/share/icons/hicolor/512x512/apps/com.mitchellh.ghostty.png";
+            picture-options = "centered";
+            primary-color = "#000000000000";
+            secondary-color = "#000000000000";
+          };
+          "org/gnome/desktop/interface" = {
+            color-scheme = "prefer-dark";
+          };
+          "org/gnome/desktop/notifications" = {
+            show-in-lock-screen = false;
+          };
+          "org/gnome/desktop/screensaver" = {
+            lock-enabled = false;
+            picture-uri = "file://${pkgs.ghostty}/share/icons/hicolor/512x512/apps/com.mitchellh.ghostty.png";
+            picture-options = "centered";
+            primary-color = "#000000000000";
+            secondary-color = "#000000000000";
+          };
+          "org/gnome/desktop/session" = {
+            idle-delay = mkUint32 0;
+          };
+          "org/gnome/shell" = {
+            disable-user-extensions = false;
+            enabled-extensions = builtins.map (x: x.extensionUuid) (
+              lib.filter (p: p ? extensionUuid) config.environment.systemPackages
+            );
+          };
+        };
+      }
+    ];
+  };
+
+  programs.geary.enable = false;
+
+  services.gnome = {
+    gnome-browser-connector.enable = false;
+    gnome-initial-setup.enable = false;
+    gnome-online-accounts.enable = false;
+    gnome-remote-desktop.enable = false;
+    rygel.enable = false;
+  };
+
+  system.activationScripts = {
+    face = {
+      text = ''
+        mkdir -p /var/lib/AccountsService/{icons,users}
+
+        cp ${pkgs.ghostty}/share/icons/hicolor/1024x1024/apps/com.mitchellh.ghostty.png /var/lib/AccountsService/icons/ghostty
+
+        echo -e "[User]\nIcon=/var/lib/AccountsService/icons/ghostty\n" > /var/lib/AccountsService/users/ghostty
+
+        chown root:root /var/lib/AccountsService/users/ghostty
+        chmod 0600 /var/lib/AccountsService/users/ghostty
+
+        chown root:root /var/lib/AccountsService/icons/ghostty
+        chmod 0444 /var/lib/AccountsService/icons/ghostty
+      '';
+    };
+  };
+}

nix/vm/common-plasma6.nix

@@ -0,0 +1,21 @@
+{...}: {
+  imports = [
+    ./common.nix
+  ];
+
+  services = {
+    displayManager = {
+      sddm = {
+        enable = true;
+        wayland = {
+          enable = true;
+        };
+      };
+    };
+    desktopManager = {
+      plasma6 = {
+        enable = true;
+      };
+    };
+  };
+}