add systemd service example

README.md

@@ -19,6 +19,9 @@ netnsd daemon [--config <config.toml>]
 Start the `netnsd` daemon, applying the configured namespace configuration and
 running any proxies.
 
+See the [systemd service example](./netnsd.service) for an example of how to run
+the daemon with systemd.
+
 You can tell the daemon to reload the configuration with `pkill -sighup netnsd`.
 
 Note that, to minimize interruption of anything using the namespaces, stopping

netnsd.service

@@ -0,0 +1,14 @@
+[Unit]
+Before=network.target
+
+[Service]
+# Set the log level
+Environment="RUST_LOG=info"
+ExecStart=/usr/bin/netnsd daemon
+Restart=on-failure
+# Tell systemd to send SIGUP when reloading the service instead of restarting the process.
+# This lets the user reload the config without interrupting any open forwarded connections.
+Type=notify-reload
+
+[Install]
+WantedBy=multi-user.target