Add initial session / systemd integration

Cargo.lock

@@ -813,6 +813,7 @@ dependencies = [
  "clap",
  "keyframe",
  "profiling",
+ "sd-notify",
  "smithay",
  "smithay-drm-extras",
  "tracing",
@@ -1186,6 +1187,12 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e1cf6437eb19a8f4a6cc0f7dca544973b0b78843adbfeb3683d1a94a0024a294"
 
+[[package]]
+name = "sd-notify"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "621e3680f3e07db4c9c2c3fb07c6223ab2fab2e54bd3c04c3ae037990f428c32"
+
 [[package]]
 name = "sharded-slab"
 version = "0.1.4"

Cargo.toml

@@ -12,6 +12,7 @@ bitflags = "2.3.3"
 clap = { version = "4.3.21", features = ["derive"] }
 keyframe = { version = "1.1.1", default-features = false }
 profiling = "1.0.9"
+sd-notify = "0.4.1"
 smithay-drm-extras = { version = "0.1.0", path = "../smithay/smithay-drm-extras" }
 tracing = "0.1.37"
 tracing-subscriber = { version = "0.3.17", features = ["env-filter"] }

resources/niri-session

@@ -0,0 +1,30 @@
+#!/bin/bash
+
+# Make sure there's no already running session.
+if systemctl --user -q is-active niri.service; then
+  echo 'A niri session is already running.'
+  exit 1
+fi
+
+# Reset failed state of all user units.
+systemctl --user reset-failed
+
+# Set the current desktop for xdg-desktop-portal.
+export XDG_CURRENT_DESKTOP=niri
+
+# Ensure the session type is set to Wayland for xdg-autostart apps.
+export XDG_SESSION_TYPE=wayland
+
+# Import the login manager environment.
+systemctl --user import-environment
+
+# DBus activation environment is independent from systemd. While most of
+# dbus-activated services are already using `SystemdService` directive, some
+# still don't and thus we should set the dbus environment with a separate
+# command.
+if hash dbus-update-activation-environment 2>/dev/null; then
+    dbus-update-activation-environment --all
+fi
+
+# Start niri and wait for it to terminate.
+exec systemctl --user --wait start niri.service

resources/niri.desktop

@@ -0,0 +1,6 @@
+[Desktop Entry]
+Name=Niri
+Comment=A scrollable-tiling Wayland compositor
+Exec=niri-session
+Type=Application
+DesktopNames=niri

resources/niri.service

@@ -0,0 +1,9 @@
+[Unit]
+Description=A scrollable-tiling Wayland compositor
+BindsTo=graphical-session.target
+Wants=graphical-session-pre.target
+After=graphical-session-pre.target
+
+[Service]
+Type=notify
+ExecStart=/usr/bin/niri

src/main.rs

@@ -19,6 +19,7 @@ use std::ffi::OsString;
 use backend::Backend;
 use clap::Parser;
 use niri::Niri;
+use sd_notify::NotifyState;
 use smithay::reexports::calloop::EventLoop;
 use smithay::reexports::wayland_server::{Display, DisplayHandle};
 use tracing_subscriber::EnvFilter;
@@ -121,4 +122,9 @@ fn main() {
             }
         })
         .unwrap();
+
+    // Tell systemd we're stopping.
+    if let Err(err) = sd_notify::notify(false, &[NotifyState::Stopping]) {
+        warn!("error notifying systemd: {err:?}");
+    }
 }

src/niri.rs

@@ -1,8 +1,10 @@
 use std::collections::HashMap;
 use std::os::unix::io::AsRawFd;
+use std::process::Command;
 use std::sync::{Arc, Mutex};
 use std::time::Duration;
 
+use sd_notify::NotifyState;
 use smithay::backend::renderer::element::surface::{
     render_elements_from_surface_tree, WaylandSurfaceRenderElement,
 };
@@ -149,6 +151,27 @@ impl Niri {
             socket_name.to_string_lossy()
         );
 
+        if std::env::var_os("NOTIFY_SOCKET").is_some() {
+            // We're starting as a systemd service. Export our variables and tell systemd we're
+            // ready.
+            let rv = Command::new("/bin/sh")
+                .args([
+                    "-c",
+                    "systemctl --user import-environment WAYLAND_DISPLAY && \
+                     hash dbus-update-activation-environment 2>/dev/null && \
+                     dbus-update-activation-environment WAYLAND_DISPLAY",
+                ])
+                .spawn();
+            if let Err(err) = rv {
+                warn!("error spawning shell to import environment into systemd: {err:?}");
+            }
+
+            // Notify systemd we're ready.
+            if let Err(err) = sd_notify::notify(false, &[NotifyState::Ready]) {
+                warn!("error notifying systemd: {err:?}");
+            };
+        }
+
         let display_source = Generic::new(
             display.backend().poll_fd().as_raw_fd(),
             Interest::READ,