Optionally install systemd service files.

If --with-systemd is given when running the configure script, two
systemd service files will be installed. There is a template
tinc@.service, which can be used to control individual instances of
tinc. For example:

systemctl enable tinc@foo

Will create an instance for tinc with netname foo. There is also a
tinc.service, which can be used to start and stop all instances at once.

systemd/Makefile.am

@@ -0,0 +1,4 @@
+if WITH_SYSTEMD
+systemddir = @systemd_path@
+dist_systemd_DATA = tinc.service tinc@.service
+endif

systemd/tinc.service

@@ -0,0 +1,20 @@
+# This is a mostly empty service, but allows commands like stop, start, reload
+# to propagate to all tinc@ service instances.
+
+[Unit]
+Description=Tinc VPN
+Documentation=info:tinc
+Documentation=man:tinc(8) man:tinc.conf(5)
+Documentation=http://tinc-vpn.org/docs/
+After=network.target
+Wants=network.target
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=/bin/true
+ExecReload=/bin/true
+WorkingDirectory=/etc/tinc
+
+[Install]
+WantedBy=multi-user.target

systemd/tinc@.service

@@ -0,0 +1,19 @@
+[Unit]
+Description=Tinc net %i
+Documentation=info:tinc
+Documentation=man:tinc(8) man:tinc.conf(5)
+Documentation=http://tinc-vpn.org/docs/
+PartOf=tinc.service
+ReloadPropagatedFrom=tinc.service
+
+[Service]
+Type=simple
+WorkingDirectory=/etc/tinc/%i
+ExecStart=/usr/sbin/tincd -n %i -D
+ExecReload=/usr/sbin/tinc -n %i reload
+Restart=on-failure
+RestartSec=5
+TimeoutStopSec=5
+
+[Install]
+WantedBy=tinc.service