nixos/xmonad: import and make reloadable

Import nixos/modules/services/x11/window-managers/xmonad.nix from
nixpkgs de121de16ef947bc8e8bfdaa37b5c6cc506050c6 and turn it into
a user service that reloads xmonad whenever its configuration changes.

2 files changed, 211 insertions, 0 deletions

diff --git a/krebs/3modules/upstream/window-managers/default.nix b/krebs/3modules/upstream/window-managers/default.nix
new file mode 100644
index 000000000..eecadca7e
--- /dev/null
+++ b/krebs/3modules/upstream/window-managers/default.nix
@@ -0,0 +1,22 @@
+{
+  imports = [
+    # Replace upstream xmonad module with one that will be reloaded if changed.
+    #
+    # This module is intended to be upstreamed once fully tested.
+    # The patch to be committed can be obtained using:
+    #
+    # diff -u <nixpkgs/nixos/modules/services/x11/window-managers/xmonad.nix> \
+    #         <stockholm/tv/3modules/window-managers/xmonad.nix>
+    #
+    {
+      disabledModules = [ "services/x11/window-managers/xmonad.nix" ];
+      imports = [ ./xmonad.nix ];
+      nixpkgs.overlays = [(self: super: {
+        writers = super.writers // {
+          writeHaskellBin = name: spec: with import <stockholm/lib>;
+            super.writers.writeHaskellBin name (removeAttrs spec ["ghcArgs"]);
+        };
+      })];
+    }
+  ];
+}
diff --git a/krebs/3modules/upstream/window-managers/xmonad.nix b/krebs/3modules/upstream/window-managers/xmonad.nix
new file mode 100644
index 000000000..356fa46bf
--- /dev/null
+++ b/krebs/3modules/upstream/window-managers/xmonad.nix
@@ -0,0 +1,189 @@
+{pkgs, lib, config, ...}:
+
+with lib;
+let
+  inherit (lib) mkOption mkIf optionals literalExample;
+  cfg = config.services.xserver.windowManager.xmonad;
+
+  ghcWithPackages = cfg.haskellPackages.ghcWithPackages;
+  packages = self: cfg.extraPackages self ++
+                   optionals cfg.enableContribAndExtras
+                   [ self.xmonad-contrib self.xmonad-extras ];
+
+  xmonad-vanilla = pkgs.xmonad-with-packages.override {
+    inherit ghcWithPackages packages;
+  };
+
+  xmonad-config =
+    let
+      xmonadAndPackages = self: [ self.xmonad ] ++ packages self;
+      xmonadEnv = ghcWithPackages xmonadAndPackages;
+      configured = pkgs.writers.writeHaskellBin "xmonad" {
+        ghc = cfg.haskellPackages.ghc;
+        libraries = xmonadAndPackages cfg.haskellPackages;
+        inherit (cfg) ghcArgs;
+      } cfg.config;
+    in
+      pkgs.runCommandLocal "xmonad" {
+        nativeBuildInputs = [ pkgs.makeWrapper ];
+      } ''
+        install -D ${xmonadEnv}/share/man/man1/xmonad.1.gz $out/share/man/man1/xmonad.1.gz
+        makeWrapper ${configured}/bin/xmonad $out/bin/xmonad \
+          --set NIX_GHC "${xmonadEnv}/bin/ghc" \
+          --set XMONAD_XMESSAGE "${pkgs.xorg.xmessage}/bin/xmessage"
+      '';
+
+  xmonad = if (cfg.config != null) then xmonad-config else xmonad-vanilla;
+in {
+  meta.maintainers = with maintainers; [ lassulus xaverdh ivanbrennan ];
+
+  options = {
+    services.xserver.windowManager.xmonad = {
+      enable = mkEnableOption "xmonad";
+      haskellPackages = mkOption {
+        default = pkgs.haskellPackages;
+        defaultText = "pkgs.haskellPackages";
+        example = literalExample "pkgs.haskell.packages.ghc784";
+        description = ''
+          haskellPackages used to build Xmonad and other packages.
+          This can be used to change the GHC version used to build
+          Xmonad and the packages listed in
+          <varname>extraPackages</varname>.
+        '';
+      };
+
+      extraPackages = mkOption {
+        default = self: [];
+        defaultText = "self: []";
+        example = literalExample ''
+          haskellPackages: [
+            haskellPackages.xmonad-contrib
+            haskellPackages.monad-logger
+          ]
+        '';
+        description = ''
+          Extra packages available to ghc when rebuilding Xmonad. The
+          value must be a function which receives the attrset defined
+          in <varname>haskellPackages</varname> as the sole argument.
+        '';
+      };
+
+      enableContribAndExtras = mkOption {
+        default = false;
+        type = lib.types.bool;
+        description = "Enable xmonad-{contrib,extras} in Xmonad.";
+      };
+
+      config = mkOption {
+        default = null;
+        type = with lib.types; nullOr (either path str);
+        description = ''
+          Configuration from which XMonad gets compiled. If no value is
+          specified, a vanilla xmonad binary is put in PATH, which will
+          attempt to recompile and exec your xmonad config from $HOME/.xmonad.
+          This setup is then analogous to other (non-NixOS) linux distributions.
+
+          If you do set this option, you likely want to use "launch" as your
+          entry point for xmonad (as in the example), to avoid xmonad's
+          recompilation logic on startup. Doing so will render the default
+          "mod+q" restart key binding dysfunctional though, because that attempts
+          to call your binary with the "--restart" command line option, unless
+          you implement that yourself. You way mant to bind "mod+q" to
+          <literal>(restart "xmonad" True)</literal> instead, which will just restart
+          xmonad from PATH. This allows e.g. switching to the new xmonad binary
+          after rebuilding your system with nixos-rebuild.
+
+          If you actually want to run xmonad with a config specified here, but
+          also be able to recompile and restart it from a copy of that source in
+          $HOME/.xmonad on the fly, you will have to implement that yourself
+          using something like "compileRestart" from the example.
+          This should allow you to switch at will between the local xmonad and
+          the one NixOS puts in your PATH.
+        '';
+        example = ''
+          import XMonad
+          import XMonad.Util.EZConfig (additionalKeys)
+          import Control.Monad (when)
+          import Text.Printf (printf)
+          import System.Posix.Process (executeFile)
+          import System.Info (arch,os)
+          import System.Environment (getArgs)
+          import System.FilePath ((</>))
+
+          compiledConfig = printf "xmonad-%s-%s" arch os
+
+          compileRestart resume =
+            whenX (recompile True) $
+              when resume writeStateToFile
+                *> catchIO
+                  ( do
+                      dir <- getXMonadDataDir
+                      args <- getArgs
+                      executeFile (dir </> compiledConfig) False args Nothing
+                  )
+
+          main = launch defaultConfig
+              { modMask = mod4Mask -- Use Super instead of Alt
+              , terminal = "urxvt" }
+              `additionalKeys`
+              [ ( (mod4Mask,xK_r), compileRestart True)
+              , ( (mod4Mask,xK_q), restart "xmonad" True ) ]
+        '';
+      };
+
+      xmonadCliArgs = mkOption {
+        default = [];
+        type = with lib.types; listOf str;
+        description = ''
+          Command line arguments passed to the xmonad binary.
+        '';
+      };
+
+      ghcArgs = mkOption {
+        default = [];
+        type = with lib.types; listOf str;
+        description = ''
+          Command line arguments passed to the compiler (ghc)
+          invocation when xmonad.config is set.
+        '';
+      };
+
+    };
+  };
+  config = mkIf cfg.enable {
+    services.xserver.windowManager = {
+      session = [{
+        name = "xmonad";
+        start = ''
+           systemctl --user start --wait xmonad.service &
+           waitPID=$!
+        '';
+      }];
+    };
+
+    system.userActivationScripts.xmonad-reload = /* sh */ ''
+      if ${pkgs.systemd}/bin/systemctl --user is-active --quiet xmonad.service; then
+        if [ "$(readlink -f "$XDG_RUNTIME_DIR"/xmonad/xmonad)" != ${xmonad}/bin/xmonad ]; then
+          ${pkgs.systemd}/bin/systemctl --user reload xmonad.service
+        fi
+      fi
+    '';
+
+    systemd.user.services.xmonad = {
+      requisite = [ "graphical-session.target" ];
+      after = [ "graphical-session.target" ];
+      environment.PATH = mkForce "%t/xmonad";
+      environment.XMONAD_DATA_DIR = "%t/xmonad";
+      serviceConfig = rec {
+        ExecStartPre = [
+          "${pkgs.coreutils}/bin/mkdir -p %t/xmonad"
+          "${pkgs.coreutils}/bin/ln -fns ${xmonad}/bin/xmonad %t/xmonad/xmonad"
+        ];
+        ExecStart = "%t/xmonad/xmonad ${lib.escapeShellArgs cfg.xmonadCliArgs}";
+        ExecReload = ExecStartPre ++ [ "${xmonad-vanilla}/bin/xmonad --restart" ];
+      };
+    };
+
+    environment.systemPackages = [ xmonad ];
+  };
+}