Customizing my Keyboard Layout on NixOS
UPDATE: The exact methodology shown here does not work anymore. See here for an updated version.
Here’s one missing write-up on a problem I immediately faced after reinstalling my Laptop with NixOS: my customized keyboard layout was missing. I’m using Programmer Dvorak for a prettly long time now. But I usually apply two modifications:
- rearrange the numbers 0..9 from left to right (as on a “normal” keyboard, just using shift as modifier key)
- add German umlauts to A, O and U keys (on modifier level 3)
… and use AltGr as modifier key to access level 3.
On Ubuntu I had a Puppet module around that used some augeas rules to
patch /usr/share/X11/xkb/symbols/us as well as evdev.xml along it.
There are several problems with this on NixOS after all: I don’t have
puppet modifying system state, but the system is immutable. And after
all there’s simply no such file :)
So pretty obviously modifying the keyboard layout is more involved on
NixOS. I pretty quickly came to the conclusion that I would have to
patch xkeyboard-config sources and use some form of package override.
Yet I had to tackle some learning curve first …
- you cannot directly override
xorg.xkeyboardconfig = ...as that would “remove” all the other stuff from belowxorg. The trick is to override xorg with itself and merge in a (possibly recursive) hash with a changed version ofxkeyboardconfig. - overriding
xorg.xkeyboardconfigcompletely also turned out to be a bad idea as its indirectly included in almost every X.org derivation (sonixos-rebuildwanted to recompile LibreOffice et al – which I clearly didn’t want it to do) - almost close to frustration I found this configuration.nix Gist where someone obviously tries to do just the same – but the Gist doesn’t have many searchable terms (actually it’s just code), so it was really hard to find :) … his trick is to use overrideDerivation based on
xorg.xkeyboardconfigbut store it in a different variable. Then derivexorgserver,setxkbmapandxkbcompand just use the modified xkeyboard configuration there
So here’s my change to /etc/nixos/configuration.nix:
nixpkgs.config.packageOverrides = super: {
xorg = super.xorg // rec {
xkeyboard_config_dvp = super.pkgs.lib.overrideDerivation super.xorg.xkeyboardconfig (old: {
patches = [
(builtins.toFile "stesie-dvp.patch" ''
Index: xkeyboard-config-2.17/symbols/us
===================================================================
--- xkeyboard-config-2.17.orig/symbols/us
+++ xkeyboard-config-2.17/symbols/us
@@ -1557,6 +1557,34 @@ xkb_symbols "crd" {
include "compose(rctrl)"
};
+partial alphanumeric_keys
+xkb_symbols "stesie" {
+
+ include "us(dvp)"
+ name[Group1] = "English (Modified Programmer Dvorak)";
+
+ // Unmodified Shift AltGr Shift+AltGr
+ // symbols row, left side
+ key <AE01> { [ ampersand, 1 ] };
+ key <AE02> { [ bracketleft, 2, currency ], type[Group1] = "FOUR_LEVEL_ALPHABETIC" };
+ key <AE03> { [ braceleft, 3, cent ], type[Group1] = "FOUR_LEVEL_ALPHABETIC" };
+ key <AE04> { [ braceright, 4, yen ], type[Group1] = "FOUR_LEVEL_ALPHABETIC" };
+ key <AE05> { [ parenleft, 5, EuroSign ], type[Group1] = "FOUR_LEVEL_ALPHABETIC" };
+ key <AE06> { [ equal, 6, sterling ], type[Group1] = "FOUR_LEVEL_ALPHABETIC" };
+
+ // symbols row, right side
+ key <AE07> { [ asterisk, 7 ], type[Group1] = "FOUR_LEVEL_ALPHABETIC" };
+ key <AE08> { [ parenright, 8, onehalf ], type[Group1] = "FOUR_LEVEL_ALPHABETIC" };
+ key <AE09> { [ plus, 9 ], type[Group1] = "FOUR_LEVEL_ALPHABETIC" };
+ key <AE10> { [ bracketright, 0 ], type[Group1] = "FOUR_LEVEL_ALPHABETIC" };
+ key <AE11> { [ exclam, percent, exclamdown ], type[Group1] = "FOUR_LEVEL_ALPHABETIC" };
+ key <AE12> { [ numbersign, grave, dead_grave ] };
+
+ // home row, left side
+ key <AC01> { [ a, A, adiaeresis, Adiaeresis ] };
+ key <AC02> { [ o, O, odiaeresis, Odiaeresis ] };
+ key <AC04> { [ u, U, udiaeresis, Udiaeresis ] };
+};
partial alphanumeric_keys
xkb_symbols "sun_type6" {
Index: xkeyboard-config-2.17/rules/evdev.xml.in
===================================================================
--- xkeyboard-config-2.17.orig/rules/evdev.xml.in
+++ xkeyboard-config-2.17/rules/evdev.xml.in
@@ -1401,6 +1401,12 @@
</variant>
<variant>
<configItem>
+ <name>stesie</name>
+ <description>English (Modified Programmer Dvorak)</description>
+ </configItem>
+ </variant>
+ <variant>
+ <configItem>
<name>rus</name>
<!-- Keyboard indicator for Russian layouts -->
<_shortDescription>ru</_shortDescription>
'') # }
];
});
xorgserver = super.pkgs.lib.overrideDerivation super.xorg.xorgserver (old: {
postInstall = ''
rm -fr $out/share/X11/xkb/compiled
ln -s /var/tmp $out/share/X11/xkb/compiled
wrapProgram $out/bin/Xephyr \
--set XKB_BINDIR "${xkbcomp}/bin" \
--add-flags "-xkbdir ${xkeyboard_config_dvp}/share/X11/xkb"
wrapProgram $out/bin/Xvfb \
--set XKB_BINDIR "${xkbcomp}/bin" \
--set XORG_DRI_DRIVER_PATH ${super.mesa}/lib/dri \
--add-flags "-xkbdir ${xkeyboard_config_dvp}/share/X11/xkb"
( # assert() keeps runtime reference xorgserver-dev in xf86-video-intel and others
cd "$dev"
for f in include/xorg/*.h; do # */
sed "1i#line 1 \"${old.name}/$f\"" -i "$f"
done
)
'';
});
setxkbmap = super.pkgs.lib.overrideDerivation super.xorg.setxkbmap (old: {
postInstall =
''
mkdir -p $out/share
ln -sfn ${xkeyboard_config_dvp}/etc/X11 $out/share/X11
'';
});
xkbcomp = super.pkgs.lib.overrideDerivation super.xorg.xkbcomp (old: {
configureFlags = "--with-xkb-config-root=${xkeyboard_config_dvp}/share/X11/xkb";
});
};
};
After a nixos-rebuild switch I was able to setxkbmap us stesie to have
my modified layout loaded. Last but not least I switched the default
keyborad layout in configuration.nix like so:
services.xserver.layout = "us";
services.xserver.xkbVariant = "stesie";
services.xserver.xkbOptions = "lv3:ralt_switch";