bind: Add systemd unit file and install it to run at startup.

The unit file is taken from debian, but tested working.
We'll call it named.service to match the sysV initscript.

Signed-off-by: Nathaniel Roach <nroach44@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/bind/bind.mk

@@ -82,6 +82,15 @@ define BIND_INSTALL_INIT_SYSV
 	$(INSTALL) -m 0755 -D package/bind/S81named \
 		$(TARGET_DIR)/etc/init.d/S81named
 endef
+define BIND_INSTALL_INIT_SYSTEMD
+	$(INSTALL) -D -m 644 package/bind/named.service \
+		$(TARGET_DIR)/usr/lib/systemd/system/named.service
+
+	mkdir -p $(TARGET_DIR)/etc/systemd/system/multi-user.target.wants
+
+	ln -sf /usr/lib/systemd/system/named.service \
+		$(TARGET_DIR)/etc/systemd/system/multi-user.target.wants/named.service
+endef
 else
 BIND_POST_INSTALL_TARGET_HOOKS += BIND_TARGET_REMOVE_SERVER
 endif

package/bind/named.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=BIND Domain Name Server
+Documentation=man:named(8)
+After=network.target
+
+[Service]
+ExecStart=/usr/sbin/named -f -u named
+ExecReload=/usr/sbin/rndc reload
+ExecStop=/usr/sbin/rndc stop
+
+[Install]
+WantedBy=multi-user.target