add Wireguard systemd service configuration

Makefile

@@ -0,0 +1,8 @@
+all: wg
+
+wg: /etc/systemd/system/wg-gen.service /etc/systemd/system/wg-gen.path
+	systemctl enable wg-gen.{path,service}
+	systemctl start wg-gen.{path,service}
+
+/etc/systemd/system/wg-gen.%: wg/wg-gen.%
+	cp $< $@

wg/wg-gen.path

@@ -0,0 +1,8 @@
+[Unit]
+Description=Watch /etc/wireguard for changes
+
+[Path]
+PathModified=/etc/wireguard
+
+[Install]
+WantedBy=multi-user.target

wg/wg-gen.service

@@ -0,0 +1,10 @@
+[Unit]
+Description=Restart WireGuard
+After=network.target
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/systemctl restart wg-quick@wg0.service
+
+[Install]
+WantedBy=multi-user.target