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XMonad: configured recompile (#107696)

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* nixos/xmonad: xmonad config w/ghc+xmessage

When the "config" option isn't set, we use xmonad-with-packages to
provide xmonad with runtime access to an isolated ghc, ensuring it can
recompile and exec a user's local config (e.g. $HOME/.xmonad/xmonad.hs)
regardless of which ghc (if any) is on PATH.

When the "config" option is set, however, we compile a configured xmonad
executable upfront (during nixos-rebuild), and prior to this commit, it
was not provided with runtime access to an isolated ghc.

As a result, with the "config" option set, it was not possible
to recompile and exec a user's local config unless there was a
compatible version of ghc on PATH with the necessary packages (xmonad,
xmonad-contrib, etc.) in its package database. Adding such a ghc to
environment.systemPackages, e.g.

  (haskellPackages.ghcWithPackages (ps: with ps; [xmonad xmonad-contrib]))

is problematic because it adds both ghc and an unconfigured xmonad to
PATH, e.g.

  $ ls -l $(which xmonad ghc)
  lrwxrwxrwx ... /run/current-system/sw/bin/ghc -> /nix/store/...-ghc-8.10.2-with-packages/bin/ghc
  lrwxrwxrwx ... /run/current-system/sw/bin/xmonad -> /nix/store/...-ghc-8.10.2-with-packages/bin/xmonad

Having the unconfigured xmonad on PATH is particularly bad because
restarting xmonad will dump the user into the unconfigured version, and
if no local config exists (e.g. in $HOME/.xmonad/xmonad.hs), they'll be
left in this unconfigured state.

In this commmit, we give the configured xmonad runtime access to ghc
like xmonad-with-packages does for the unconfigured version. The aim
is to allow the user to switch between the nixos module's config and a
local config (e.g. $HOME/.xmonad/xmonad.hs) at will, so they can try out
config changes without performing a nixos-rebuild.

Since the xmonad on PATH is the configured executable, there's no
danger a user could unwittingly restart into the unconfigured version,
and because xmonad will refuse to recompile when no local config
exists, there's no danger a user could unwittingly recompile into an
unconfigured version.

Given that a local config exists, the recompile/restart behavior depends
on two factors:
- which entry point is used
  * 'XMonad.xmonad' (default)
  * 'XMonad.launch' (recommended in "config" option description)
- what operation is triggered (i.e. via mod+q)
  * `spawn "xmonad --recompile && xmonad --restart"` (default)
  * `restart "xmonad" True`
  * custom function

If the default 'XMonad.xmonad' entrypoint and default mod+q operation
are used, hitting mod+q will compile and exec the local config, which
will remain in use until next time the display manager is restarted.

If the entrypoint is changed to 'XMonad.launch' but mod+q left with its
default operation, hitting mod+q will have no visible effect. The logs
(as seen by running `journalctl --identifier xmonad --follow`) will show
an error,
  X Error of failed request:  BadAccess (attempt to access private resource denied)
which indicates that the shell was unable to start xmonad because
another window manager is already running (namely, the nixos-configured
xmonad).
https://wiki.haskell.org/Xmonad/Frequently_asked_questions#X_Error_of_failed_request:_BadAccess_.28attempt_to_access_private_resource_denied.29

Changing the mod+q operation to `restart "xmonad" True` (as recommended
in the "config" option's description) will allow a restart of the
nixos-configured xmonad to be triggeredy by hitting mod+q.

Finally, if the entrypoint is 'XMonad.launch', mod+q has been
bound to `restart "xmonad" True` and another key bound to a custom
recompile/restart function (e.g. `compileRestart` as shown in the
"config" option example), the user can switch between the nixos module's
config and their local config, with the custom key switching to the
local config and mod+q switching back.

* nixos/xmonad: refactor let binding

* nixos/xmonad: refactor (eliminate duplicate code)

* nixos/xmonad: install man pages

Prior to this commit, man pages were not installed if the "config"
option was set.

* nixos/xmonad: comment grammar fixups

* nixos/xmonad: writeStateToFile in example config

Calling writeStateToFile prior to recompiling and restarting allows
state (workspaces, etc.) to be preserved across the restart.

* nixos/xmonad: add ivanbrennan to maintainers

* nixos/xmonad: adjust compileRestart example

* nixos/xmonad: add missing import to example config
This commit is contained in:
Ivan 2020-12-28 11:27:36 -05:00 committed by GitHub
parent 80e3ca6f4a
commit b90c5cb703
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 38 additions and 20 deletions
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58
nixos/modules/services/x11/window-managers/xmonad.nix
View File

@ -5,25 +5,37 @@ 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 {
ghcWithPackages = cfg.haskellPackages.ghcWithPackages;
packages = self: cfg.extraPackages self ++
optionals cfg.enableContribAndExtras
[ self.xmonad-contrib self.xmonad-extras ];
inherit ghcWithPackages packages;
};
xmonad-config = pkgs.writers.writeHaskellBin "xmonad" {
ghc = cfg.haskellPackages.ghc;
libraries = [ cfg.haskellPackages.xmonad ] ++
cfg.extraPackages cfg.haskellPackages ++
optionals cfg.enableContribAndExtras
(with cfg.haskellPackages; [ xmonad-contrib xmonad-extras ]);
inherit (cfg) ghcArgs;
} cfg.config;
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 ];
meta.maintainers = with maintainers; [ lassulus xaverdh ivanbrennan ];
options = {
services.xserver.windowManager.xmonad = {
@ -72,13 +84,13 @@ in {
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 xmonads
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,
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
@ -91,6 +103,7 @@ in {
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)
@ -99,16 +112,21 @@ in {
compiledConfig = printf "xmonad-%s-%s" arch os
compileRestart = whenX (recompile True) . catchIO $ do
dir <- getXMonadDataDir
args <- getArgs
executeFile (dir </> compiledConfig) False args Nothing
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 )
[ ( (mod4Mask,xK_r), compileRestart True)
, ( (mod4Mask,xK_q), restart "xmonad" True ) ]
'';
};