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Add systemd support for niri with hot reloading #156

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598088b
lib.modules.systemd: install units under lib/systemd/<type>
DavHau May 7, 2026
8332e60
modules/niri: ship wrapper-managed user unit with hot-reload
DavHau May 7, 2026
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16 changes: 8 additions & 8 deletions checks/systemd.nix
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Original file line number Diff line number Diff line change
Expand Up @@ -279,10 +279,10 @@ let
}
);

readUserService = drv: name: builtins.readFile "${drv}/systemd/user/${name}.service";
readSystemService = drv: name: builtins.readFile "${drv}/systemd/system/${name}.service";
readUserTimer = drv: name: builtins.readFile "${drv}/systemd/user/${name}.timer";
readSystemTimer = drv: name: builtins.readFile "${drv}/systemd/system/${name}.timer";
readUserService = drv: name: builtins.readFile "${drv}/lib/systemd/user/${name}.service";
readSystemService = drv: name: builtins.readFile "${drv}/lib/systemd/system/${name}.service";
readUserTimer = drv: name: builtins.readFile "${drv}/lib/systemd/user/${name}.timer";
readSystemTimer = drv: name: builtins.readFile "${drv}/lib/systemd/system/${name}.timer";
in
pkgs.runCommand "systemd-test" { } ''
echo "Testing systemd module..."
Expand Down Expand Up @@ -314,14 +314,14 @@ pkgs.runCommand "systemd-test" { } ''

# Test 3: Service name from binName
echo "Test 3: Service name from binName"
test -f "${customBinName.outputs.systemd-user}/systemd/user/my-hello.service" || {
test -f "${customBinName.outputs.systemd-user}/lib/systemd/user/my-hello.service" || {
echo "FAIL: user service file should be named my-hello.service"
ls -la "${customBinName.outputs.systemd-user}/systemd/user/"
ls -la "${customBinName.outputs.systemd-user}/lib/systemd/user/"
exit 1
}
test -f "${customBinName.outputs.systemd-system}/systemd/system/my-hello.service" || {
test -f "${customBinName.outputs.systemd-system}/lib/systemd/system/my-hello.service" || {
echo "FAIL: system service file should be named my-hello.service"
ls -la "${customBinName.outputs.systemd-system}/systemd/system/"
ls -la "${customBinName.outputs.systemd-system}/lib/systemd/system/"
exit 1
}
echo "PASS: service name from binName"
Expand Down
2 changes: 1 addition & 1 deletion lib/modules/systemd.nix
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Expand Up @@ -61,7 +61,7 @@ let
mkOutput =
type:
let
unitDir = if type == "user" then "systemd/user" else "systemd/system";
unitDir = if type == "user" then "lib/systemd/user" else "lib/systemd/system";

serviceFile = pkgs.writeTextDir "${unitDir}/${serviceName}.service" (systemdLib.serviceToUnit svc)
.text;
Expand Down
49 changes: 46 additions & 3 deletions modules/niri/module.nix
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Expand Up @@ -122,6 +122,7 @@ let
in
{
_class = "wrapper";
imports = [ wlib.modules.systemd ];
options = {
settings = lib.mkOption {
type = lib.types.submodule {
Expand Down Expand Up @@ -304,13 +305,55 @@ in
'';
};
};
# Drop the upstream user unit; we ship our own (below) with ExecReload
# wired up to the niri IPC. Keep the desktop entry patched so display
# managers still pick up the wrapper's binary.
config.filesToExclude = [
"lib/systemd/user/niri.service"
"share/systemd/user/niri.service"
];
config.filesToPatch = [
"share/applications/*.desktop"
"share/systemd/user/niri.service"
];
config.package = config.pkgs.niri;
config.env = {
NIRI_CONFIG = toString config."config.kdl".path;

# Shell-launched wrapper: same behaviour as upstream -- niri reads the
# immutable, build-pinned config straight from /nix/store.
config.env.NIRI_CONFIG = toString config."config.kdl".path;

Comment on lines +319 to +323
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@zimward zimward May 14, 2026

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Suggested change
# Shell-launched wrapper: same behaviour as upstream -- niri reads the
# immutable, build-pinned config straight from /nix/store.
config.env.NIRI_CONFIG = toString config."config.kdl".path;
config.env.NIRI_CONFIG = toString config."config.kdl".path;

this should be obvious. no point in having a LLM comment for it

# Systemd-launched session: bootstrap a mutable runtime copy under
# $XDG_RUNTIME_DIR (systemd specifier %t) and point niri at it via
# `--config`. ExecReload re-stamps that file with the latest immutable
# snapshot and asks niri to re-read it via IPC, so config-only switches
# apply without dropping the session.
Comment on lines +324 to +328
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@zimward zimward May 14, 2026

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Suggested change
# Systemd-launched session: bootstrap a mutable runtime copy under
# $XDG_RUNTIME_DIR (systemd specifier %t) and point niri at it via
# `--config`. ExecReload re-stamps that file with the latest immutable
# snapshot and asks niri to re-read it via IPC, so config-only switches
# apply without dropping the session.

no longer relevant

config.systemd = {
description = "A scrollable-tiling Wayland compositor";
bindsTo = [ "graphical-session.target" ];
before = [
"graphical-session.target"
"xdg-desktop-autostart.target"
];
wants = [
"graphical-session-pre.target"
"xdg-desktop-autostart.target"
];
after = [ "graphical-session-pre.target" ];
serviceConfig = {
Slice = "session.slice";
Type = "notify";
ExecStartPre = "${config.pkgs.coreutils}/bin/install -Dm644 ${config."config.kdl".path} %t/niri/config.kdl";
ExecStart = "${config.exePath} --session --config %t/niri/config.kdl";
ExecReload = [
"${config.pkgs.coreutils}/bin/install -Dm644 ${config."config.kdl".path} %t/niri/config.kdl"
"${config.exePath} msg action load-config-file"
];
Comment on lines +344 to +349
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@zimward zimward May 14, 2026

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Suggested change
ExecStartPre = "${config.pkgs.coreutils}/bin/install -Dm644 ${config."config.kdl".path} %t/niri/config.kdl";
ExecStart = "${config.exePath} --session --config %t/niri/config.kdl";
ExecReload = [
"${config.pkgs.coreutils}/bin/install -Dm644 ${config."config.kdl".path} %t/niri/config.kdl"
"${config.exePath} msg action load-config-file"
];
ExecStart = "${config.exePath} --session --config ${config."config.kdl".path}";
ExecReload = "${config.exePath} msg action load-config-file --path ${config."config.kdl".path}";

with niri 26.05 there is no reason to do mutable copies at the config file can just be relocated (infact i implemented that feature exactly for this reason in niri :) )

};
# Tell NixOS's switch-to-configuration to convert every "needs
# restart" verdict into `systemctl --user reload niri.service`, so
# config-only switches reload the live session via ExecReload instead
# of killing it. The flag is read out of the unit's [Service] section
# at switch time (X-ReloadIfChanged=true).
reloadIfChanged = true;
};
config.meta.maintainers = [
lib.maintainers.zimward
Expand Down
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